bluuebunny/crossref_metadata_2025_split huggingface dataset:
Discoloration of a Freezer Cylinder
Authors: Suess S.J. 
Published: May 2019

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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.