bluuebunny/crossref_metadata_2025 huggingface dataset:
Steel Wire Cracked at Welded Joint
Authors: Naumann Friedrich Karl , Spies Ferdinand
Published: May 2019

A 2.3 mm diam steel wire broke during cable twisting. The fracture occurred obliquely to the longitudinal axis of the wire and showed a constriction at the end. Therefore it was a ductile fracture. File mark type work defects were noticeable on the wire surface at both sides of the fracture, but they had no effect on the breakage of the wire. Away from the fracture area, the wire had a normal structure of hyperfine lamellar pearlite (sorbite) of a “patented” and cold drawn steel wire. In the vicinity of the fracture, the cementite of the pearlite was partially spheroidized, while at the fracture itself it was completely spheroidized. Therefore the wire was locally annealed at this point. It was likely that the wire cracked at this point during the last drawing and then broke during twisting due to its lower strength in the weakened cross section after prior deformation.
Damaged Impellers in a Rotary Pump
Authors: Kauczor Egon
Published: May 2019

Two damaged impellers made of austenitic cast iron came from a rotary pump used for pumping brine mixed with drifting sand. On one of the impellers, pieces were broken out of the back wall in four places at the junction to the blades. The fracture edges followed the shape of the blade. Numerous cavitation pits were seen on the inner side of the front wall visible through the breaks in the back wall. The back wall of the as yet intact second impeller which did not show such deep cavitation pits was cracked in places along the line of the blades. The microstructure consisted of lamellar graphite and carbides in an austenitic matrix and was considered normal for the specified material GGL Ni-Cu-Cr 15 6 2. It was concluded that the cause of the damage was porosity at the junction between back wall and blades arising during the casting process. Cavitation did not contribute to fracture but also could have led to damage in the long term in the case of a sound casting. It is therefore advisable in the manufacture of new impellers to take care not only to avoid porosity but also to use alloy GGL Ni-Cu-Cr 15 6 3, which has a higher chromium content and is more resistant to cavitation.
Failure Analysis of Computer Data Storage Disc Drive Systems
Authors: Tripathi K.C.
Published: May 2019

This paper deals with disk drive failures that occur in the interface area between the head and disk. The failures often lead to the loss of stored data and are characterized by circumferential microscratches that are usually visible to the unaided eye. The recording media in disk drives consists of a metal, glass, ceramic, or plastic substrate coated with a magnetic material. Data errors are classified as ‘soft’ or ‘hard’ depending on their correctability. Examination has shown that hard errors are the result of an abrasive wear process that begins with contact between head and disk asperities. The contact generates debris that, as it accumulates, increases contact pressure between the read-write head and the surface of the disk. Under sufficient pressure, the magnetic coating material begins wearing away, resulting in data loss.
Electron Fractography Pinpoints Cause of Fatigue Fracture
Authors: Lauchner Edward A. , Herfert Robert E.
Published: May 2019

After completing a fatigue test of an aluminum alloy component machined from a 7079-T6 forging, technicians noted a 5 in. crack which ran longitudinally above and through the flange. When the fracture face was examined by light microscopy, observers could not ascertain the exact mode of fracture. Electron fractography revealed that five different modes of crack growth were operative as the part failed. Region 1 was a shallow zone (about 0.002 in. at its deepest) of dimpled structure typical of an overload failure. Region 2 was a zone that grew by a stress corrosion mechanism. Through a fatigue mechanism was operative in Region 3, it was not the cause of the large crack. Region 4, which covered 50% of the fracture area, developed mainly by stress corrosion. This zone gradually changed into the combination of intergranular and transgranular overload in Region 5, which covered approximately the remaining 50% of the fracture. Apparently, after stress corrosion moved halfway through, the part failed by overload. This failure analysis proved that a crack, originally thought to be a fatigue failure, was actually a stress corrosion crack.
Cracking of Machined End Frame Steel Forgings After Heat Treatment
Authors: Das A. K. , Thippeswamy B. M. , Prasad J.
Published: May 2019

A number of machined end frame steel forgings made of Cr-Si-Mn alloy showed tiny cracks during magnetic particle inspection after heat treatment. The cracks were mostly confined to base edges and fillet radius. No significant abnormality was observed in chemical composition and microstructure. SEM, optical microscopy, and gas analysis revealed that the subsurface discontinuous cracks at the bore edges and in the fillet radius of the heat-treated end frame component had occurred due to hydrogen embrittlement, and not because of faulty heat treatment. This conclusion was supported by the presence of cracklike indications in machined bore surface of the annealed part.
SO2 Heat Exchanger Failure
Authors: Reitz W.
Published: May 2019

Critical heat exchanger components are usually manufactured from durable steels, such as stainless steel, which exhibit good strength and corrosion resistance. Failure of a heat exchanger occurred due to specification of a plain carbon steel that did not survive service in the SO2 vapor environment. However, failure analysis showed that cavitation erosion was the responsible failure mechanism, not corrosion as might be expected.
Discoloration of a Freezer Cylinder
Authors: Suess S.J.
Published: May 2019

A nickel alloy cylinder plated with chromium along its inner liner, installed in a commercial ice cream freezer, showed gray discoloration along its OD surface. The discolored parts exhibited significantly reduced cooling efficiency as compared with new cylinders. During operation, the OD of the cylinder was exposed to liquid ammonia refrigerant containing lubricant from the compressor. The lubricant (mineral oil) was intended to separate from the ammonia and be recirculated through the compressor. Nondestructive portable optical microscopy, XRF, EDS, and XPS analyses showed that the discoloration on the cylinder was associated with metal oxidation products coated with a thin oil film. One of the recommendations was to plate the OD of the cylinder with hard chromium to increase its resistance to erosion. Another recommendation was to reduce the amounts of water contamination in the refrigerant.
Metallurgical Failure Analysis of Titanium Wing Attachment Bolts
Authors: Stevenson M.E. , McDougall J.L. , Cline K.G.
Published: May 2019

Two titanium alloy wing attachment bolts from a commercial jetliner failed during the course of a routine service operation. Failure of the bolts occurred during the re-torque process as the wing was being reattached. Metallurgical failure analysis indicated that the fracture mechanism was ductile overload and that the mechanical properties of the bolts were consistent with exemplar bolts that had been supplied. After eliminating other sources of excessive load application, the most probable cause of failure was ascribed to variances between the frictional characteristics of the bolt at the time of re-torque and at the time of initial torque application several years earlier.
The Role of Metallography and Fractography in the Analysis of Gun Tube Failures
Authors: Faller J. G. , Simmons W. C.
Published: May 2019

Important clues about the probable cause of a gun tube explosion were obtained from a fractographic and metallographic examination of the fragments. The size, distribution, and surface markings of fragments may be used to localize the explosion and deduce its intensity. Microstructural features such as voids, adiabatic shear, and structural surface alterations also indicate the explosion intensity and further allow a comparison of the tube structure near and away from the explosion zone. These, and other metallurgical characteristics, are illustrated and discussed for cases of accidental and deliberately caused explosions of large caliber gun tubes.
A Microstructural Examination of Hot Corrosion of a Co-Cr-Fe Alloy Cast Burner Nozzle from a Coal Gasification Plant
Authors: Cao S. , Brooks Charlie R. , Whittaker Gary
Published: May 2019

A microstructural analysis has been made of a burner nozzle removed from service in a coal gasification plant. The nozzle was a casting of a Co-29wt%Cr-19wt%Fe alloy. Extensive hot corrosion had occurred on the surface. There was penetration along grain boundaries, and corrosion products in these regions were particularly rich in S, and also contained Al, Si, O, and Cl. The grain boundaries contained Cr-rich particles which were probably Cr23-C6 type carbides. In the matrix, corrosion occurred between the Widmanstatten plates. Particles were found between these plates, most of which were rich in Cr and O, and probably were Cr2-O3 oxides. Other matrix particles were found which were rich in Al, O, and S. The corrosion was related to these grain boundary and matrix particles, which either produced a Cr-depleted zone around them or were themselves attacked.
Pitting of 3003 Aluminum
Authors: Ryding D.G. , Allen D. , Lee R.
Published: May 2019

The Advanced Photon Source (APS) is a state-of-the-art synchrotron light source. The storage ring vacuum chamber is fabricated from 6061 extruded aluminum. Water connections to the vacuum chambers that were fabricated from 3003 aluminum had developed water leaks, which were subsequently remedied after considerable investigations.
Failure of Lead Bath Heaters in a Hypersonic Wind Tunnel
Authors: Scipioni G. , Marloth R.T. , Es-Said O.S.
Published: May 2019

The working fluid of a hypersonic wind tunnel is freon 14 heated in molten-metal-bath heat exchangers. The coils of the heaters have failed several times from various causes. They have been replaced each time with a stainless steel deemed more appropriate, but they continue to fail. In this case study, the history of failures is traced, the causes are analyzed, and recommendations are made for future design and maintenance. Coils fabricated from AISI 316 should provide satisfactory service life if reasonable precautionary measures are observed during maintenance and testing.
Solving an Aluminum Bracket Failure
Authors: Young B. K.
Published: May 2019

An aircraft engine in which an in-flight fire had occurred was dismantled and examined. A bracket assembly fabricated from 2024 aluminum, one of several failed components, was of prime interest because of apparent heat damage. Scanning electron microscopy was used to compare laboratory-induced fractures made at room and elevated temperatures with the bracket failure. The service failure exhibited grain separation and loss of delineation of the grain boundaries due to melting. SEM revealed deep voids between grains and tendrils that connected grains, which resulted from surface tension during melting. Microscopic examination of polished, etched section through the fractured surface verified intergranular separation and breakdown of grain facets. The absence of any reduction of thickness on the bracket assembly at the point of fracture, along with evidence of intense heat at this point, indicated that little stress had been applied to the part. Comparisons of the service failure and laboratory-induced failures in conjunction with macroscopic and metallographic observations showed that the bracket assembly failed because an intense, localized flame had melted the material.
Failure of Large Screen Spherical Bearing-Crushed Stone
Authors: Walton H.W.
Published: May 2019

The contamination of lubrication with powdered stone resulted in progressive wear of the internal surfaces of a bearing. Because of the motion of rollers, the inner race exhibited an unusual cyclic washboard wear pattern. Because of a lack of bearing conformity, wear progressed into severe coarse-grain spalling.
Failure of Coal Crushing Plant Taper Bearing
Authors: Walton H.W.
Published: May 2019

Butterfly-shaped microstructural features in tempered martensite in an otherwise clean steel suggested that overloading led to premature spalling of a coal-crushing plant taper bearing. Extensive rolling contact fatigue occurred because of the overload condition. The crusher was designed to handle soft lignite coals but had been used to crush hard deep-mined anthracite coals.
Improper Fabrication Rotating Blades Results in Premature Failure
Authors: Tatar Fred W.
Published: May 2019

A number of rotating blades in a diffuser at a sugar beet processing plant fabricated from rectangular bars cut from rolled carbon-manganese steel plate fractured brittlely. However, apparently identical blades underwent significant plastic deformation without fracture. Inspection of both fractured and bent blades revealed similar preexisting cracks at the toes of bar attachment welds. Metallographic examination of the bent and the fractured bars revealed they had been cut parallel and transverse, respectively, to the rolling direction of the steel plate. Due to the combined effects of the low fracture toughness of the plate on planes parallel in the rolling direction, the presence of the preexisting cracks, and the relatively large section thickness of the bars, the bars whose lengths were transverse to the rolling direction fractured brittlely when subjected to impact loads. Had the poor transverse properties of thick-section plate been recognized, and all the bars properly cut with respect to the rolling direction, the premature fractures would not have occurred.
Metallic Inclusions in Steel
Authors: Naumann Friedrich Karl , Spies Ferdinand
Published: May 2019

Examples of metallic inclusions in steels of various types are presented. The structure of an inclusion in an annealed Fe-1C-1.5Cr steel consisted of ferrite with lamellar pearlite. The carbon content of the inclusion was therefore considerably lower than that of the chromium steel and was adapted to the latter by diffusion only at the periphery of the inclusion. In another section of a hardened piece of the same chromium steel, the steel in this case had a structure of martensite with hypereutectic carbide, while the inclusions consisted of a very fine laminated eutectoid of the lower pearlite range (Troostite). In a pipe of 18-8 austenitic stainless steel a weakly magnetizable spot of limited size was found. This inclusion too was probably more alloy-deficient than the austenitic steel, similar to the ones described above. All three cases were casting defects.
Boiler Tube Cracked During Bending
Authors: Naumann Friedrich Karl , Spies Ferdinand
Published: May 2019

A seamless hot-drawn boiler tube NW 300 of 318 mm OD and 9 mm wall thickness made of steel 15Mo3 was bent with sand filling after preheating allegedly to 1000 deg C. In the process it had cracked repeatedly in the drawn fiber. The composition corresponded to specifications, but exceptionally high copper content was noticeable. Microstructural examination showed the damage was due to overheating and burning during preheating and bending. Furthermore, crack formation was promoted by precipitation of metallic copper that had penetrated into the austenitic grain boundaries under the influence of tensile stresses that arose during bending. This phenomenon is known as “solder brittleness.”
Cracked Cast Iron Crankcases
Authors: Naumann Friedrich Karl , Spies Ferdinand
Published: May 2019

The front wall of a cast iron crankcase cracked at the transition from the comparatively minor wall thickness to the thick bosses for the drilling of the bolt holes. Metallographic examination showed the case was aggravated by the fact that the casting had a ferritic basic structure and the graphite in part showed a granular formation, so that strength of the material was low. In a second crankcase with the same crack formation the structure in the thick-wailed part was better. But it also showed granular graphite in the ferritic matrix in the thin-walled part between the dendrites of the primary solid solution precipitated in the residual melt. A third crankcase had fractures in two places, first at the frontal end wall and second at the thinnest point between two bore holes. In all three cases casting stresses caused by unfavorable construction and rapid cooling were responsible for the crack formation. A fourth crankcase had cracked in the bore-hole of the frontal face. In this case the cause of the fracture was the low strength of a region that was caused by a bad microstructure further weakened by the bore hole.
Broken-Off Bearing Bosses of Scrap Shears
Authors: Naumann Friedrich Karl , Spies Ferdinand
Published: May 2019

Three bearing bosses from the cover of scrap shears were sent in for examination. They had torn off the base plate to which they had been welded by fillet welds all around. Two of these were examined. They showed entirely the same symptoms. The bosses had broken away on three sides along the welds. The cleaved fractures in the burned notches propagated partially above and partially below several incipient cracks which may have been fatigue fractures. Metallographic sections showed that the fractures had occurred either at the burned notches near the transition from the weld to the sheet, or else they ran in the sheet material next to the weld. The quality of the welds could not be judged because the opposite fracture pieces to which they adhered had not been sent in. It was concluded that the breakaway of these bosses was at least favored by overheating and hardening.
Cracking of Pipe Nipples in Welding
Authors: Naumann Friedrich Karl , Spies Ferdinand
Published: May 2019

A number of seamless pipe nipples of 70 mm diam and 3.5 mm wall thickness made of steel type 35.8 were oxyacetylene welded to collectors of greater wall thickness with a round bead. X-ray examination showed crack initiation in the interior of the nipples close to the root of the weld seam. The cracks only appeared where the originally deposited bead was remelted in the regions of overlap. Given the construction and welding technique used, it would have been preferable to make the nipples of a steel lower in sulfur content. However, by taking advantage of all the potential in shaping and welding technology, it should be possible to prevent crack formation with steel type 35.8 of normal composition.
Welded Pipes with Hard Spots
Authors: Naumann Friedrich Karl , Spies Ferdinand
Published: May 2019

Pipes made of low-carbon Thomas steel had been welded longitudinally employing the carbon-arc process with bare electrode wire made for argon-shielded arc welding. Difficulties were encountered during the cutting of threads because of the presence of hard spots. Microstructural examination showed welding conditions were such that a carburizing atmosphere developed, which led to an increase in carbon content and hardening at certain locations such as terminal bells and lap joints. This explained the processing difficulties during the threading operation.
Cracks in Flame Hardened Operation Handles
Authors: Kauczor Egon
Published: May 2019

Operation handles produced from C45 steel showed many fine cracks at the flame hardened noses. The cracks ran from the corners of indentations caused by the tool during alignment. Metallographic investigation showed the nose was overheated during flame hardening. It was concluded that the numerous hardening cracks were caused by abrupt quenching from over-heating temperature and by local stress concentrations due to indentations of the tool caused during alignment.
Investigation of a Case Hardened Sleeve
Authors: Naumann Friedrich Karl , Spies Ferdinand
Published: May 2019

A case-hardened sleeve made of C 15 (Material No. 1.0401) was flattened at two opposing sides and had cracked open at these places, the crack initiating at a face plane. The wall of the sleeve was 9 mm thick, but the flat ends were machined down to 5.5 mm from the outside. The customer had specified a 2 mm case depth and a hardness of at least HRC 55 at a depth of 1.5 mm. An etched cross section of the cracked end showed that the case layer had a depth of 2.3 mm, so that the sleeve was almost through-hardened at the flat ends. While the core material with the full wall thickness had the quench structure of low-carbon steel, the structure of the flattened area consisted of coarse acicular martensite with a small amount of pearlite (quench troostite) and ferrite. Therefore the sleeve was overheated and probably quenched directly from case. To prevent damage, it would have been necessary to have a lower case depth, carburize less deeply, and prevent overheating that causes brittleness and leads also to increased case depth, or else use a fine-grained steel of lower hardenability.
Brittle Zinc Layer on a Hot-Galvanised Hook
Authors: Kauczor Egon
Published: May 2019

The surface of a hook did not possess the smooth and shiny zinc bloom surface normally observed on hot galvanized steel parts but was matte and rough. Large cracks were observed in the zinc layer. The hook was made of silicon-killed alloy steel 41Cr4. A silicon content of 0.27% was established analytically. Silicon accelerates the reaction between iron and zinc, which should have been taken into account in the present case by reducing the dip time or a small addition of aluminum (0.1 to 0.2%) to the galvanizing bath to retard the extremely rapid growth of the zinc layer and the strong alloy formation. Even in the case of steel parts with lower silicon contents the reaction between iron and zinc can continue until the pure zinc layer has been consumed entirely if the work piece is not cooled sufficiently after withdrawal.
Cast Steel Housing with Grain Boundary Precipitates
Authors: Naumann Friedrich Karl , Spies Ferdinand
Published: May 2019

In a housing made of cast steel GS 20MoV12 3, weighing 42 tons, precipitates were found on the austenitic grain boundaries during metallographic inspection. According to their shape and type they were recognized as carbides that precipitated during tempering. In addition, a much coarser network of rod-shaped and plate-shaped precipitates was found, that probably corresponded to the primary grain boundaries, or to the grain boundaries or twin planes of the austenite formed during solidification of the melt. These particles could have been aluminum nitride judging by their shape and order of precipitation. Tests showed that a subsequent removal of this defect by solutioning was impractical because the annealing temperature was too high. To avoid this defect in the future the sole recommendation is to accelerate the cooling rate through the critical region between 1200 to 900 deg C to such an extent as is practicable with respect to machinability.
Steel Casting with Insufficient Strength Properties
Authors: Naumann Friedrich Karl , Spies Ferdinand
Published: May 2019

In a steel foundry, tensile and bend specimens of castings made in a 2-ton basic arc furnace showed, at irregular intervals, regions with coarse-grained fractures where the specimens broke prematurely, so that the specified strength and toughness values could not be reached. Several cast tensile specimens and some forcibly-broken pieces of the flanges of armature yokes made of cast steel GS C 25 according to DIN 17 245 were investigated. Microscopic examination showed that the cause of damage was the superabundant use of aluminum as deoxidizer. According to recommendations, the aluminum addition was reduced by one-half. Since then, there have been no additional rejects due to insufficient tensile and bend values.
Steel Socket Pipe Conduit Cracked Next to Weld Seam
Authors: Naumann Friedrich Karl , Spies Ferdinand
Published: May 2019

A steel socket pipe conduit NW 150 cracked open during pressure testing next to the weld seam almost along the entire circumference. The crack occurred in part in the penetration notch and in part immediately adjacent to it. While the uncracked pipe showed the light etch shading of a low-carbon steel in which the zone heated during welding was delineated only slightly next to the seam, the other pipe was etched much darker, i.e., higher in carbon, and the heated zone appeared to stand out darkly against the basic material. The overlapping weld was defect-free and dense. The uncracked pipe consisted of soft steel that obviously was made for this purpose, while the cracked pipe consisted of a strongly-hardenable steel which contained not only more carbon and manganese than customary but also a considerable amount of chromium. Therefore, the damage was caused by a mix-up of materials that allowed an unsuitable steel to be used for the weldment.
An Example of Decarburization in Alloy Steels and Its Effect on Further Processing
Authors: Chatterjee P. K.
Published: May 2019

One percent Cr-Mo low alloy constructional steel is widely used for high tensile applications, e.g., for manufacture of high tensile fasteners, heat treated shafts and axles, for automobile applications such as track pins for high duty tracked vehicles etc. The steel is fairly through hardening and heat treatment does not present any serious difficulty. Care is still required in processing to avoid decarburization. In an application of track pins for tracked vehicles, bars about 22 mm diam were required in heat treated and centerless-ground condition prior to induction hardening of the surface. Indifferent results were obtained in induction hardening; cracks were noticed, and patchy hardness figures were obtained on the final product in several batches. Metallographic examination of transverse sections through the defective areas showed decarburization to varying degrees, i.e., from partial to total decarburization. Observations suggested the defects originated at the stages of ingot making and rolling. This was apparently the reason for complete decarburization of the area with original surface defect which opened up further in the oxidizing atmosphere of the furnace with low melting clinkers from scale and furnace lining filling up the crevice of the original defect.
Brittleness in Copper and Copper Alloys With Particular Reference to Hydrogen Embrittlement
Authors: Matting A. , Ziegler Ruth
Published: May 2019

Hydrogen embrittlement is the brittleness affecting copper and copper alloys containing oxygen which develops during heat treatment at temperatures of about 400 deg C (752 deg F) and above in an atmosphere containing hydrogen. The phenomenon of hydrogen embrittlement of copper and its alloys is illustrated by examples from practice and reference is made to data from recent publications on the subject. Embrittlement due to this cause can only be identified by microscopic examination because other modes of failure in copper; e.g., from heat cracking, mechanical overload, the formation of low melting point eutectics or corrosion; show a similar appearance when investigated on a macroscopic scale.
Use of Electron Fractography to Diagnose Cracking in a 7075-T6 Aluminum Forging
Authors: Scott James A.
Published: May 2019

A forging of 7075-T6 aluminum alloy, which formed a support for the cylinder of a cargo door, cracked at an attachment hole. Fluorescent penetrant inspection showed the crack ran above and below the hole out onto the machined flat surface of the flange. A 6500x electron fractograph proved the crack to be a forging defect called a cold shut. Because defects of this type are usually detected when the raw forging is inspected, this occurrence was considered to be an isolated instance.
Analysis of Center Burst During Hot Forging
Authors: Vamsi Krishna B. , Sidhu R.K.
Published: May 2019

Carbon steel axle forgings were rejected due to internal cracks observed during final machining. To determine the cause of the cracks, the preforms of the forging were analyzed in detail at each stage of the forging. The analysis revealed a large central burst in the intermediate stage of the forging preform, which subsequently increased in the final stage. A high upset strain during forging, especially in the final stage, accentuated the center burst by high lateral flow of the metal. It was concluded that the center burst of the axle forging resulted from a high concentration of nonmetallic inclusions in the central portion of the raw bar stock rather than the usual problem of improper forging temperature. Strict control over the inclusion content in the raw material by changing the vendor eliminated the problem.
Assessing the Durability of Aluminum Castings
Authors: Aliya D.
Published: May 2019

A new supplier for aluminum die castings was being evaluated, and the castings failed to meet the durability test requirements. Specifically, the fatigue life of the castings was low. Initial inspection of the fatigue fracture surfaces revealed large-scale porosity visible to the naked eye. New castings with reduced porosity also failed the durability tests. The fatigue fracture surfaces of additional casting fragments were very rough and contained multiple ratchet marks along the inner fillet. These observations indicated the fatigue process was heavily influenced by the presence of surface imperfections. Improving the surface finish or choosing a stronger alloy, were more likely to improve part durability than reducing the porosity.
Failure of Die Cast Aluminum Cluster Bomb Tailcone Assemblies
Authors: Pepi M.
Published: May 2019

Cluster bomb tailcone assemblies each containing two aluminum die-cast components were rejected because of the poor surface condition of the die castings. Numerous heat checks were found on the surfaces of the tailcones and radiographic inspection revealed inclusions, gas holes, and shrinkage defects in the castings. Most of the components failed to meet required mechanical properties because of these casting defects.
Crankshaft with Torsion Fatigue Fractures in Inductively Surface-Hardened Crank Pin
Authors: Naumann Friedrich Karl , Spies Ferdinand
Published: May 2019

A crankshaft was overloaded on a test stand and suffered an incipient crack in the crank pin. The crack run generally parallel to the longitudinal axis and branched off at the entrance into the two fillets at the transition to the crank arm. It consisted of many small cracks, all of which propagated at an angle of approximately 45 deg to the longitudinal axis, and therefore were caused by torsion stresses. Neither macroscopic nor microscopic examination determined any material or processing faults. Experience has shown that torsion vibration fractures of this kind usually appear in comparatively short journal pins at high stresses. This crankshaft fracture was an example of the damage that is caused or promoted neither by material nor heat treatment mistakes nor by defects of design or machining, but solely by overstressing.
Evaluation of Pitting on a Spur Gear
Authors: Alban Lester E.
Published: May 2019

Three spur gears made from 8622 Ni-Cr-Mo alloy steel formed a straight-line train in a speed reducer on a rail-mounted overslung lumber carrier. The gears were submitted for nondestructive examination and evaluation, with no accompanying information or report. Two teeth on one of the gears were found to be pitted, one low on profile and the adjacent tooth high on profile. The mating gear had a similar characteristic, two adjacent teeth with evidence of pitting and the same difference in profile. It was correctly deduced that the pitting occurred because the gears were in a static position under a reverberating load for an extended period of time.
Failures of TiN-Coated Wobblers in a Hydraulic Assembly
Authors: Dhar Suranjeeta , Mohammed Fameeda , Xu Laura , Fontana Raymond
Published: May 2019

Extensive slipper/wobbler failures occurred in the integrated drive generators that incorporated TiN coated wobblers, during the production acceptance test. Similar coated wobblers had passed the application tests. The nature of the failure was extensive gouging of the wobbler surface with discoloration and coating removal. The substrate material was E52100 which was through-hardened to HRC 55-60. The slippers that were in contact with the coated wobbler surface were made of AISI 06 material. A synthetic oil was used as the hydraulic fluid in the application. The failure in the wobblers was caused by lack of temperature control during application which resulted in localized surface rehardening. It was established that there was a significant difference in the grade of the hydraulic fluid that was used in the two test programs. Use of superior grade of hydraulic fluid was recommended in this case for the production acceptance tests.
Failure Analysis of a Pilot Scale Melter
Authors: Imrich K.J.
Published: May 2019

Failure of a pilot scale test melter resulted from severe overheating of an Inconel 690 (690) jacketed molybdenum electrode. Extreme temperatures were required to melt the glass during this campaign because the feed material contained a very high waste loading. Metallurgical evaluation revealed the presence of an alloy containing nickel and molybdenum in several ingots found on the bottom of the melter and on a drip which had solidified on the electrode sheath. This indicates that a major portion of the electrode assembly was exposed to a temperature of at least 1317 deg C, the nickel/molybdenum eutectic temperature. Small regions on the end of the 690 sheath showed evidence of melting, indicating that this localized region exceeded 1345 deg C, the melting point of 690. In addition to nickel, antimony was found on the grain boundaries of the molybdenum electrode. This also contributed to the failure of the electrode. The source of the antimony was not identified but is believed to have originated from the feed material. Metallurgical evaluation also revealed that nickel had attacked the grain boundaries of the molybdenum/tungsten drain valve. This component did not fail in service; however, intergranular attack led to degradation of the mechanical properties, resulting in the fracture of the drain valve tip during disassembly. Antimony was not observed on this component.
Analysis of Hot Rolled Steel Transit Damage
Authors: Dillon Barry
Published: May 2019

Investigation of alleged corrosion damage to hot-rolled steel during transit requires metallurgical, chemical, and corrosion knowledge. Familiarity with non-destructive techniques and sampling procedures is necessary. A complete record of shipment history is also required, including the purchasing specifications and observations and photographs taken during surveys enroute. A frequent conclusion of such investigations is that the alleged corrosion is of no significance or did not occur during the voyage.
Overload Failure of a Crane on an Offshore Platform Related to Stress-Corrosion Cracking
Authors: Ibidunni A. O. , Bookwalter J. C. , Guenther D. A.
Published: May 2019

Failed ferrous components were analyzed from a crane that operated on an offshore platform. The crane failed during operation and fell into the sea. The brake spring on the boom hoist was found to have fractured in four places. The spring contained a line defect (seam) that was the source of each crack. The fracture of the oil quenched and tempered (HRC 50 ASTM A229) spring was by stress-corrosion cracking after the crane fell into the sea because fatigue cannot account for the fractures observed. The crane failure was caused by an overload created by the operator catching a free-falling load.
Levels of Employability Skills and Organisational Citizenship Behaviourof University Secretarial Staff In South-West, Nigeria
Authors: Muyiwa Adeyemi , Dosunmu Margaret Moronke , Bukki Abolaji Olugbenga
Published: May 2019

The skills and competencies exhibited by the secretarial staff in a University setting show how vast is such secretary in the art of delivery of his/her services.  A secretarial staff has been considered to be the brain box of any organisation.  They are incharge of all information emanating and disseminating from the establishment; as such the role of the secretarial staff as the custodian of information in the university cannot be over-emphasized.  The aim of the study was to determine the levels of the University secretarial staff employability skills and organizational citizenship behaviour in South-West, Nigeria.  The study adopted a descriptive research design of ex-post facto type. Two research questions were raised. The sample for the study consisted of 1,209 secretarial staff in 36 universities in South-West, Nigeria selected through stratified random sampling technique.  Three instruments were used for data collection, namely: Demographic Data Form, Graduate Employability Scale (GESS), ‘r’=0.86; Organisational Citizenship Behaviour Scale (OCBS), ‘r’=0.96. Multiple Regression Analysis (MRA) and Pearson Product Moment Correlation (PPMC) were used to analyse the data at 0.05 level of significance.  The results revealed that the University secretarial staff generally possessed a high level of employability skills (50.5%) and organizational citizenship behaviour (50.8%).It was concluded that the secretarial staff generally possessed the employability skills and organisational citizenship behaviour which are needed to perform optimally in their duties. The study recommended, among others, that the secretarial staff should endeavour to seek for more knowledge to equip them with relevant employability skills that will make them to be assets to the organization. The University secretarial staff should be exposed to regular training programmes with an emphasis on how to enhance their employability skills and further improve their knowledge. Also, there is need to compensate any secretarial staff who displays the traits of organizational citizenship behavior.This will serve as motivation for other secretarial staff.
Pre-Service Teachers’ Assessment of Student Learning In Science Education
Authors: Coronado Edsel O
Published: May 2019

This research was conducted to examine the tools, strategies, and problems encountered in assessing student learning by pre-service teachers in science during their on-and-off campus clinical experience. An explanatory sequential mixed method design was used in the study. Three instruments were used in this study: The Assessment Checklist for Student Teachers in Science, Focus Group Discussion (FGD) Questions, and the In-depth Interview Questions. 17 pre-service teachers participated from one teacher education institution. Findings of the study using Kruskal-Wallis One-way Analysis of Variance and Thematical Analysis using Phenomenological Reduction Method revealed the assessment tools used most frequently and least frequently, assessment strategies, and the problems encountered by pre-service teachers in science in assessing student learning. The findings also revealed that there was a significant difference in the use of rubric (p value=0.045) as the least frequently used assessment tool by pre-service teachers in science when grouped according to specialization.
School Change Management: A Multi-frame Analysis
Authors: AHMED Eman I
Published: May 2019

The purpose of the present paper is to examine how the school leaders frame their own experiences of managing change within the school system. The mixed method design was used to answer the research questions and understand the research problems. Both the qualitative and the quantitative data were used to identify the frames orienting school leaders to manage change within the school setting. The obtained data showed that the participants employed most of the frames (structural, political, human resource, and symbolic) in managing school change. The data revealed that the human resource frame appeared universal in most of the cases. Understanding principals’ perceptions of change management can help practitioners as well as academics to work more efficiently and address the needs of the school leaders.
A Structural Model of Academic Buoyancy, Aptitude, and School Environment on the Mathematics Achievement of Pre-service Teachers
Authors: Gellor Joamel P.
Published: May 2019

The study determined the direction and magnitude of the relationships of academic buoyancy, aptitude and school environment towards mathematics achievement of the pre-service teachers through Structural Equation Modeling. Maximum Likelihood was used to estimate while Chi-square/degrees of freedom, Goodness of Fit Index, Normal Fit Index, Tucker-Lewis Index, Comparative Fit Index, and Root Mean Square Error of Approximation indices were used to evaluate the goodness of fit of the hypothesized models. The best fit model for the mathematics achievement of pre-service teachers is best anchored on aptitude supported by school environment. Academic buoyancy is necessary but insufficient for mathematics achievement.
Effective Metacognitive Strategies to Boost English as a Foreign Language Reading Comprehension
Authors: Iobidze Meri
Published: May 2019

The article investigates effective strategies for teaching English as a foreign language reading skill. Main emphasis is placed on the use of metacognitive strategies which help students to reflect on mental processes occurring before, during and after the process of reading. Thus, utilizing metacognitive strategies leads to successful performance and reading comprehension. The research dealt with the significance of metacognitive strategies as a tool for successful accomplishment in the process of reading and the tasks related to this process. The research was based on quantitative approach, as the data obtained through experiment were necessary to shape and study the statistics of achievement and failures of learners. The research revealed that using metacognitive strategies can be advantageous to improve EFL learners' metacognitive reading comprehension skill. Moreover, metacognitive awareness in learners lead to higher self-efficacy among learners. They become high achievers at learning EFL. 

The findings of this study might have implications for learners, teachers, and material-developers in the field of English language teaching and learning
Determining the Significance Level of Vocabulary Teaching Tools and Activities in Teaching Turkish as a Foreign Language through Analytical Hierarchy Process
Authors: Arslan Mustafa , Kang Suat
Published: May 2019

As vocabulary is an important component of language teaching and there exist certain problems in students’ vocabulary skills, traditional and modern teaching methods used in Turkish as a foreign language teaching are discussed in the article. The frequency of use and the success rates were taken into consideration in the determination of the methods. In this context, a survey was developed and administered within Analytic Hierarchy Process (AHP) for teachers of Turkish to foreigners in order to determine the significance level of vocabulary teaching methods in Turkish as a foreign language. The survey consisted of comparative questions for determining the significance levels of vocabulary acquisition methods used in teaching Turkish as a foreign language. The data collected in this research were analyzed in Microsoft Excel program and the results were presented as statistical tables. According to the findings, the significance level of communicative teaching methods conducted through visual and auditory tools and activities were determined to be the first in vocabulary acquisition in teaching Turkish as a foreign language. Videos and movies were seen to be the first in the order of significance level within vocabulary teaching through visual and audio tools. Role-play activities were determined to be the first in the order of significance of level. Interactive course CDs and smart boards became the most effective tools in teaching vocabulary in terms of educational technologies. Course-books and workbooks were identified as the most preferred tools in printed publications. According to the results of the study, the tools applied by students that address multi-senses were seen to be the most preferred techniques in vocabulary acquisition in teaching Turkish as a foreign language. The results of this research will contribute to updating the methods to be used in teaching / learning Turkish as a foreign language vocabulary. In addition, they will help to improve the course-books and other materials to be developed.
STUDI FENOMENOLOGI KEJADIAN HIPEREMESIS GRAVIDARUM PADA IBU HAMIL TRIMESTER I
Authors: Rofi'ah Siti , Widatiningsih Sri , Arfiana Arfiana
Published: May 2019

Mual muntah adalah gejala yang normal dalam kehamilan. Namun, apabila berlebihan sehingga mengganggu pekerjaan sehari-hari dan keadaan umum menjadi burukÂ yang disebut hiperemesis gravidarum dapat berakibat fatal bagi ibu dan janin. Â Tujuan penelitian ini adalah menggali berbagai hal tentang kejadian hiperemesis gravidarum yang dialami oleh ibu hamil trimester I. Penelitian ini menggunakan metode kualitatif dengan pendekatan fenomenologi deskriptif. Partisipan berjumlah lima belas orang terdiri dari ibu hamil, suami ibu hamil, bidan rumah sakit dan bidan desa. Pengumpulan data menggunakan wawancara mendalam dan analisa menggunakan teknik induktif. Penelitian ini mengidentifikasi tujuh tema yaitu 1) Persepsi tentang hiperemesis gravidarum; Â 2) Faktor - faktor yang mempengaruhi hiperemesis gravidarum; Â 3) Kronologi hiperemesis gravidarum; 4) Pengobatan baik farmakologis maupun non farmakologis yang diterima ibu hamil dalam mengatasi hiperemesis gravidarum dari sejak keluhan awal; 5) Bentuk dukungan yang diterima ibu baik dari keluarga maupun tenaga kesehatan pada saat mengalami hiperemesis gravidarum; 6) Harapan ibu terhadap keluarga dan tenaga kesehatan untuk hiperemesis gravidarum; 7) Hambatan dalam mengatasi hiperemesis gravidarum. Harapannya agar bidan lebih aktif dalam memberikan informasi tentang hiperemesis gravidarum beserta cara mengatasinya; bagi ibu hamil supaya mencari informasi tentang hiperemesis gravidarum dari berbagai sumber dan mencari sumber dukungan untuk mengatasi hiperemesis gravidarum.
PAJANAN LOGAM BERAT (Pb) PADA SEDIMEN ALIRAN SUNGAI TEMPAT PEMBUANGAN AKHIR (TPA)
Authors: Anwar M. Choiroel , Rudijanto I.W Hari , Cahyono Tri
Published: May 2019

TPA Kaliori yang merupakan pengganti dari TPA Gunung Tugel di Kabupaten Banyumas, mulai beroperasi pada tahun 2013. Setiap hari menampung sampah yang dihasilkan oleh kota Purwokerto danÂ diperkirakan sekitar 40 â€“ 50 truk/hari.Â Terjadinya longsor sampah ke tempat penampungan lindi menyebabkan lindi tidak terwadahi dan menyebabkan terjadinya pencemaran badan air serta sumur penduduk yang menjadikankan masyarakat sekitar berdemo untuk menutup TPA . Tujuan penelitian untuk mengetahui pajanan logam berat pada sedimen aliran sungai tempat pembuangan akhir. Jenis penelitian Â merupakan penelitian observasional dengan rancangan Â cross sectional study.Â Populasi penelitian Â adalah : Lindi, badan air, air sumur dan darah.Â Pengambilan sampel dilakukan dua kali yaitu pada tanggal Â 16 dan 19 Oktober 2018.Â Parameter pencemaran yang diteliti meliputi : Â Â pH, suhu air, TDS, Kekeruhan, warnaÂ dan Pb. Alat yang di gunakan yaitu pH meter, termometer, TDS dan untuk pengujian kandungan timbal (Pb), BOD dan COD dilakukan di UPTD Laboratorium Kesehatan Kabupaten PurbalinggaÂ serta laboratorium Prodia untuk mengukur kadar Pb di darah. HasilÂ penelitian didapatkan Â rerata hasil Pb pada IPAL yaitu 0,260 mg/l. Rerata hasil Pb dalam badan air/ saluran terbuka yaitu 0,204 mg/l. Rerata hasil Pb dalam air sumur 1 dengan jarak 100m adalah 0,061 mg/l, sumur 2 dengan jarak 135m adalah 0,052 mg/l dan sumur 3 dengan jarak 120 m adalah 0,047 mg/l.Â Rerata hasil Pb dalam darah manusia 5,6 Âµg/dL dari empat responden dengan jarak rumah yang berbeda. Hasil penelitian dapat disimpulkaanÂ Â bahwaÂ kadar Pb pada IPAL dan Badan air Â melebihi baku mutu yang ditetapkan yaitu 0,1 mg/l dan dari tingkat pajanan pencemaran sudah berada dalam darah manusia. Dari hasil penelitian ini dapat kami sarankan untuk dilakukan perbaikan pada tempat pengolahan Lindi