bluuebunny/crossref_metadata_2025 huggingface dataset:
Cracking on the Parting Line of Closed-Die Forgings
Authors: Koprowski Anthony J.
Published: May 2019

An investigation was conducted to determine the factors responsible for the occasional formation of cracks on the parting lines of medium plain carbon and low-alloy medium-carbon steel forgings. The cracks were present on as-forged parts and grew during heat treatment. Examination revealed that areas near the parting line exhibited a large grain structure not present in the forged stock. High-temperature scale was also found in the cracks. It was concluded that the cracks were caused by material being folded over the parting line. The folding occurred because of a mismatch in the forgings and from material flow during trimming and/or material flow during forging.
Brittle Fracture in a Large Grain Storage Bin
Authors: Becker William T.
Published: May 2019

A 22 m (72 ft) diameter filled grain storage bin made from a 0.2% carbon steel collapsed at a temperature of −1 to 4 deg C (30 to 40 deg F). Failure analysis indicated that fracture occurred in a two-step process: first downward, by ductile failure of small ligament from a bolt hole near the bottom of the tank to create a crack 25 mm (1 in.) long, and then upward, by brittle fracture through successive 1.2 m (4ft) wide sheets of ASTM A446 material. Site investigation showed that the concrete base pad was not level. Chemical analysis indicated that the material had a high nitrogen content (0.020%). The allowable stress based on yield was estimated using four different design criteria. Correlation among those results was poor. The different criteria indicated that the material was loaded from the maximum allowable to approximately 30% less than allowable. Nevertheless, at this stress level, fracture mechanics indicated that the 25 mm (1 in.) starter crack exceeded or was very near the critical crack length for the material. Additional factors not taken into account in the design equations included cold work from a hole punching operation, thread imprinting in bolt holes, and an additional hoop stress created by forcing an incorrectly formed panel to fit the pad base radius. These factors increased the nominal design stress to a sufficiently large value to cause the critical crack length to be exceeded.
Failure of a Squeeze-Clamped Polyethylene Natural Gas Pipeline
Authors: Jones Robert E. , Bradley Walter L.
Published: May 2019

A high-density polyethylene (HDPE) natural gas distribution pipe (Grade PE 3306) failed by slow, stable crack growth while in residential service. The leak occurred at a location where a squeeze clamp had been used to close the pipe during maintenance. Failure analysis showed that the origin of the failure was a small surface crack in the inner pipe wall produced by the clamping. Fracture mechanics calculations confirmed that the suspected failure process would result in a failure time close to the actual time to failure. It was recommended that: materials be screened for susceptibility to the formation of the inner wall cracks since it was not found to occur in pipe typical of that currently being placed in service; pipes be re-rounded after clamp removal to minimize residual stresses which caused failure; and a metal reinforcing collar be placed around the squeeze location after clamp removal.
Solvent-Induced Cracking Failure of Polycarbonate Ophthalmic Lenses
Authors: Lochanski Edward C.
Published: May 2019

Metal-framed polycarbonate (PC) ophthalmic lenses shattered from acetone solvent-induced cracking. The lenses exhibited primary and secondary cracks with solvent swelling and crazing. A laboratory accident splashed acetone onto the lenses. The metal frames gripped approximately two-thirds of the lenses' periphery and introduced an unevenly distributed force on the lenses. To prevent future failures, it was recommended to protect PC from service environments with solvents, such as acetone; or from marking pens, adhesives or soaps which contain undesirable solvents; and to not apply excessive stress on ophthalmic lenses in the form of working or residual stresses.
Creep Failure of a Superheater Tube Promoted by Graphitization
Authors: Hahn Sarah Jane , Kurtz Tom
Published: May 2019

Tube 3 from a utility boiler in service for 13 years under operating conditions of 540 deg C (1005 deg F), 13.7 MPa (1990 psi) and 1,189,320 kg/h (2,662,000 lb/h) incurred a longitudinal rupture near its 90 deg bend while Tube 4 from the same boiler exhibited deformation near its bend. Metallographic examination revealed creep voids near the rupture in addition to graphite nodules. Exposure of the SA209 Grade T1A steel tubing to a calculated mean operating temperature of 530 deg C (983 deg F) for the 13 years resulted in graphitization and subsequent creep failure in Tube 3. The deformation in Tube 4 was likely the result of steam washing from the Tube 3 failure. Graphitization observed remote from the rupture in Tube 3 and in Tube 4 indicated that adjacent tubing also was susceptible to creep failure. In-situ metallography identified other graphitized tubes to be replaced during a scheduled outage.
Failure of a Reformer Tube Weld by Cracking
Authors: Monteiro Sergio N. , Araujo Paulo Augusto M.
Published: May 2019

An HK-40 alloy tubing weld in a reformer furnace of a petrochemical plant failed by leaking after a shorter time than that predicted by design specifications. Leaking occurred because of cracks that passed through the thickness of the weldment. Analysis of the cracked tubing indicated that the sulfur and phosphorus contents of the weld metal were higher than specified, the thickness was narrower at the weld, and the mechanical resistance of the weld metal was lower than specified. Cracking initiated at the weld root by coalescence of creep cavities. Propagation and expansion was aided by internal carburization. Quality control of welding procedures and filler metal was recommended.
Fatigue Failure of a Carbon Steel Piston Shaft on an Extrusion Press Billet-Loading Tray
Authors: Green Phillip
Published: May 2019

A recurring piston shaft failure problem on the billet-loading tray of an extrusion press was investigated. Two shafts fractured within a period of 10 days. The shaft was machined from normalized EN3 (AISI C1022) steel stock without further treatment. Visual, microstructural, chemical, and mechanical (hardness and tensile properties) analyses of failed shaft specimens were conducted. The examinations showed that the shafts had failed by fatigue. It was recommended that a low-alloy steel (e.g., 3% Ni-Cr) in the hardened and tempered condition and subjected to shot-peening surface-hardening treatment be used. The provision of a stop to reduce bending stresses was also recommended.
Fracture of the Bottom Platen of an 800 Ton Hydraulic Press
Authors: Eryürek I.B. , Capa M.
Published: May 2019

The side supporting flange of the bottom platen of an 800 ton hydraulic press fractured after 9 x 10's cycles under a maximum load of 530 tons. The platen material specified in the design was cast steel 52. Metallographic examination of the fracture surface indicated that the platen had failed in fatigue as a result of a high stress concentration in a sharp 0.6 mm (0.02 in.) radius fillet. Stress analysis and fracture mechanics predictions revealed that there was also danger of fatigue failure for platens with the design radius of 10 mm (0. 4 in.) if the press operates at 800 tons. It was recommended that the remaining life of similar presses be assessed periodically controlling the cracks, their dimensions, and their propagation rates. An increase in the radius of the fillet was also recommended.
Cracking in an Aircraft Nose Landing Gear Strut
Authors: Barter S.A. , Athiniotis N. , Clark G.
Published: May 2019

A crack was detected in one arm of the right-hand horizontal brace of the nose landing gear shock strut from a large military aircraft. The shock strut was manufactured from a 7049 aluminum alloy forging in the shape of a delta. A laboratory investigation was conducted to determine the cause of failure. It was concluded that the arm failed because of the presence of an initial defect that led to the initiation of fatigue cracking. The fatigue cracking grew in service until the part failed by overload. The initial defect was probably caused during manufacture. Fleet-wide inspection of the struts was recommended.
Failed Mixer Pivot Support of An Army Attack Helicopter
Authors: Champagne Victor K. , Wechsler Gary , Pepi Marc
Published: May 2019

A forged, cadmium-plated electroslag remelt (ESR) 4340 steel mixer pivot support of the rotor support assembly located on an Army attack helicopter was found to be broken in two pieces during an inspection. Visual inspection of the failed part revealed significant wear on surfaces that contacted the bushing and areas at the machined radius where the cadmium coating had been damaged, which allowed corrosion pitting to occur. Optical microscopy showed that the crack origin was located at the machined radius within a region that was severely pitted. Electron microscopy revealed that most of the fracture surface failed in an intergranular fashion. Energy dispersive spectroscopy determined that deposits of sand, corrosion and salts were found within the pits. The failure started by hydrogen charging as a result of corrosion, and was aggravated by the stress concentration effects of pitting at the radius and the high notch sensitivity of the material. The failure mechanism was hydrogen-assisted and was most likely a combination of stress-corrosion cracking and corrosion fatigue. Recommendations were to improve the inspection criteria of the component in service and the material used in fabrication.
Failure Analysis of a Space Shuttle Solid Rocket Booster Auxiliary Power Unit (APU) Fuel Isolation Valve
Authors: Sanders J.H. , Jerman G.A.
Published: May 2019

A precipitation-hardened stainless steel poppet valve assembly used to shut off the flow of hydrazine fuel to an auxiliary power unit was found to leak. SEM and optical micrographs revealed that the final heat treatment designed for the AM-350 bellows material rendered the AM-355 poppet susceptible to intergranular corrosive attack (IGA) from a decontaminant containing hydroxy-acetic acid. This attack provided pathways for which fluid could leak across the sealing surface in the closed condition. It was concluded that the current design is flight worthy if the poppet valve assembly passes a preflight helium pressure test. However a future design should use the same material for the poppet and bellows so that the final heat treatment will produce an assembly not susceptible to IGA.
Failure Analysis of an Exhaust Diffuser Assembly
Authors: Sampath K. , Chaudhari M.D.
Published: May 2019

An exhaust diffuser assembly failed prematurely in service. The failure occurred near the intake end of the assembly and involved fracture in the diffuser cone (Corten), diffuser in take flange (type 310 stainless steel), diffuser exit flange (type 405 stainless steel), expansion bellows (Inconel 600), and bellows intake flange (Corten). Individual segments of the failed subassemblies were examined using various methods. The analysis indicated that the weld joint in the diffuser intake flange (type 310 stainless steel to Corten steel) contained diffusion-zone solidification cracks. The joints had been produced using the mechanized gas-metal arc welding process. Cracking was attributed to improper control of welding parameters, and failure was attributed to weld defects.
Quench Cracking in a Turntable Rail
Authors: Panontin Tina L.
Published: May 2019

Persistent cracking in a forged 1080 steel turntable rail in a wind tunnel test section was investigated. All cracks were oriented transverse to the axis of the rail, and some had propagated through the flange into the web. Through-flange cracks had been repair welded. A section of the flange containing one through-flange crack was examined using various methods. Results indicated that the cracks had initiated from intergranular quench cracks caused by the use of water as the quenching medium. Brittle propagation of the cracks was promoted by high residual stresses acting in conjunction with applied loads. Repair welding was discontinued to prevent the introduction of additional residual stress., Finite-element analysis was used to show that the rail could tolerate existing cracks. Periodic inspection to monitor the degree of cracking was recommended.
Failure of Nickel-Base Superalloy Heat-Exchanger Tubes in a Black Liquor Heater
Authors: Kattus J. Robert
Published: May 2019

Several nickel-base superalloy (UNS N06600) welded heat-exchanger tubes used in processing black liquor in a kraft paper mill failed prematurely. Leaking occurred through the tube walls at levels near the bottom tube sheet. The tubes had been installed as replacements for type 304 stainless steel tubes. Visual and stereoscopic examination revealed three types of corrosion on the inside surfaces of the tubes: uniform attack, deeper localized corrosive attack, and accelerated uniform attack. Metallographic analysis indicated that pronounced dissimilar-metal corrosion had occurred in the base metal immediately adjacent to the weld seam. The corrosion was attributed to exposure to nitric acid cleaning solution and was accelerated by galvanic differences between the tubes and a stainless steel tube sheet and between the base metal of the tubes and their dendritic weld seams. A change to type 304 stainless steel tubing made without dendritic weld seams was recommended.
Stress-Corrosion Cracking of a Brass Tube in a Generator Air Cooler Unit
Authors: Tanner G. Mark
Published: May 2019

An arsenical admiralty brass (UNS C44300) finned tube in a generator air cooler unit at a hydroelectric power station failed. The unit had been in operation for approximately 49,000 h. Stereomicroscopic examination revealed two small transverse cracks that were within a few millimeters of the tube end, with one being a through-wall crack. Metallographic examination of sections containing the cracks showed branching secondary cracks and a transgranular cracking mode. The cracks appeared to initiate in pits. EDS analysis of a friable deposit found on the inside diameter of the tube and XRD analysis of crystalline compounds in the deposit indicated the possible presence of ammonia. Failure was attributed to stress-corrosion cracking resulting from ammonia in the cooling water. It was recommended that an alternate tube material, such as a 70Cu-30Ni alloy or a titanium alloy, be used.
Thermal Fatigue Failure in a Vaporizer
Authors: Becker W.T.
Published: May 2019

A gas-fired, ASTM A-106 Grade B carbon steel vaporizer failed on three different occasions during attempts to bring the vaporizer on line. Dye penetrant examination indicated the presence of multiple packets of ductile cracks on the inside of the coil radius at the bottom of the horizontal axis coils. Visual examination of the inside of the tubing indicated the presence of a carbonaceous deposit resulting from decomposition of the heat-exchanging fluid. Subsequent metallographic examination and microhardness testing indicated that the steel was heated to a temperature above the allowable operating temperature for the fluid. The probable cause for failure is thermal fatigue due to the localized overheating. Flow conditions inside the tubing should be reexamined to ensure suitable conditions for annular fluid flow.
Failure of AM350 Stainless Steel Bellows
Authors: Jayakumar T. , Bhattacharya D.K. , Raj Baldev
Published: May 2019

AM350 stainless steel bellows used in the control rod drive mechanism of a fast breeder reactor failed after 1000 h of service in sodium at 550 deg C (1020 deg F). Helium leak testing indicated that leaks had occurred at various regions of the welded joints between the convolutes in the bellows. The weld failure was attributed to poor quality assurance during fabrication, which resulted in cracklike openings at the fusion zone. The openings extended during tensile loading. Use of proper welding procedures and quality control measures were recommended to prevent future failures.
Liquid Metal Embrittlement of Bronze Rupture Discs
Authors: Watkins William R.
Published: May 2019

Failure of three C22000 commercial bronze rupture discs was caused by mercury embrittlement. The discs were part of flammable gas cylinder safety devices designed to fail in a ductile mode when cylinders experience higher than design pressures. The subject discs failed prematurely below design pressure in a brittle manner. Fractographic examination using SEM indicated that failure occurred intergranularly from the cylinder side. EDS analysis indicated the presence of mercury on the fracture surface and mercury was also detected using scanning auger microprobe (SAM) analysis. The mercury was accidentally introduced into the cylinders during a gas-blending operation through a contaminated blending manifold. Replacement of the contaminated manifold was recommended along with discontinued use of mercury manometers, the original source of mercury contamination.
Transgranular Stress-Corrosion Cracking Failures in AISI 304L Stainless Steel Dished Ends During Storage
Authors: Bhattacharya D.K. , Ghanamoorthy J.B. , Raj Baldev
Published: May 2019

Several type 304L stainless steel dished ends used in the fabrication of cylindrical vessels developed extensive cracking during storage. All of the dished ends had been procured from a single manufacturer and belonged to the same batch. When examined visually, several rust marks were observed, indicating contamination by rusted carbon steel particles. Liquid penetrant testing was used to determine the extent of the cracks, and in situ metallographic analysis was performed over the cracked region. The morphology of the cracks was indicative of transgranular stress-corrosion cracking (TGSCC). Conditions promoting the occurrence of the TGSCC included significant tensile stresses on the inside of the dished ends, the presence of surface contamination by iron due to poor handling practice using carbon steel implements, and storage in a coastal environment with an average temperature of 25 to 32 deg C (77 to 90 deg F), an average humidity ranging from 70 to 80%, and an atmospheric NaCl content ranging from 8 to 45 mg/m2 /day. Recommendations preventing further occurrence of the situation were strict avoidance of the use of carbon steel handling implements, strict avoidance of cleaning practices that cause long-term exposure to chlorine-containing cleaning fluid, and solution annealing of the dished ends at 1050 deg C (1920 deg F) for 1 h followed by water quenching to relieve residual stresses.
An Unusual Case of Hydrogen-Induced Failure in a Refinery Boiler Tube
Authors: Islam Moavinul
Published: May 2019

A failed SAE-192 carbon steel tube from a 6.2-MPa (900-psig), 200-Mg/h (180-ton/h) capacity refinery boiler was analyzed to determine its failure mode. Optical and SEM examination results were combined with knowledge of the boiler operating conditions to conclude that the failure was hydrogen-induced. The hydrogen was probably generated by the steam-iron reaction. The source of steam on the flue gas side could be traced to a cracked fillet weld in the boiler The failure mode was unusual in that the attack was found to originate from the flue gas side of the tube rather than the steam side.
Caustic Gouging and Caustic-Induced Stress-Corrosion Cracking of Superheater Tube U-Bends
Authors: Hearn Allen W. , Rawlinson Harold , Mark Tanner G.
Published: May 2019

Original carbon steel and subsequent replacement austenitic stainless steel superheater tube U-bend failures occurred in a waste heat boiler. The carbon steel tubes had experienced metal wastage in the form of caustic corrosion gouging, while the stainless steel tubes failed by caustic-induced stress-corrosion cracking. Sodium was detected by EDS in the internal deposits and the base of a gouge in a carbon steel tube and in the internal deposits of the stainless steel tube. The sodium probably formed sodium hydroxide with carryover moisture and caused the gouging, which was further aggravated by the presence of silicon and sulfur (silicates and sulfates). It was recommended that the tubes be replaced with Inconel 600 or 601, as a practical option until the carryover problem could be solved.
Corrosion Failure of Stainless Steel Thermowells
Authors: Bhattacharya D.K. , Raj Baldev , Lopez E.C. , Seetharaman V.
Published: May 2019

Pressure testing of a batch of AISI type 316L stainless steel thermowells intended for use in a nuclear power-plant resulted in the identification of leakage at the tips in 20% of the parts. Radiography at the tip region of representative thermowells showed linear indications along the axes. SEM examination revealed the presence of longitudinally oriented nonmetallic inclusions that were partly retained and partly dislodged. Electron-dispersive x-ray analysis indicated that the inclusions were composed of CaO. Based on the overall chemistry of the inclusion sites, the source of the CaO was determined to be slag entrapment during the steel making process. It was recommended that the thermowell blanks be ultrasonically tested prior to machining and that the design be modified to make internal pressurization possible.
Cracking of Inconel 800H in a Steam Methane Reformer Furnace
Authors: Gertler Scott R.
Published: May 2019

During 5.7 years of service, dye penetrant inspection of Inconel 800H pigtail connections regularly showed cracks at weld toes. Weld repairs were not able to prevent reoccurrence but often aggravated the condition. Samples containing small, but detectable, reducer-to-pigtail cracks showed intergranular cracks originating at weld toes and filled with oxidation product, which precluded determination of the cracking mechanism. All weldments exhibited high degrees of secondary precipitates, with original fabrication welds exhibiting higher apparent levels than repair welds. SEM/EDS analysis showed base metal grain boundary precipitates to be primarily chromium carbides, but some titanium carbides were also observed. Failure was believed to result from the synergism of thermally driven tube distortion, which resulted in over-stress, and from the intergranular oxidation products and intergranular carbides which contributed to cracking. It was recommended that stresses be reduced and /or that materials and components be changed. Refinements in welding procedures and implementation of preweld/postweld heat treatments were recommended also.
Failure of a High-Pressure Steam Pipe
Authors: D'Antonio Carmine
Published: May 2019

A high-pressure steam pipe specified to be P22 low-alloy steel failed after 25 years of service. Located at the end of the steam line, the pipe reportedly received no steam flow during normal service. Visual examination of the failed pipe section revealed a window fracture that appeared brittle in nature. Specimens from the fracture area and from an area well away from the fracture were examined metallographically and chemically analyzed. Results indicated that the pipe had failed by hydrogen damage that resulted in brittle fracture. Chemical analysis indicated that the pipe material was 1020 carbon steel, not P22. The misapplication of pipe material was considered to be a contributing factor. Position of the pipe within the system caused the localized damage.
Failure of an Embrittled Tube
Authors: Bradley S.A.
Published: May 2019

The causes of cracking of an as-drawn 90-10 cupronickel tube during mechanical working were investigated to determine the source of embrittlement. Embrittlement was sporadic, but when present was typically noted after the first process anneal. Microstructural and chemical analyses were performed on an embrittled section and on a section from a different lot that did not crack during forming. The failed section showed an intergranular fracture path. Examination of the fracture surfaces revealed the presence of tellurium at the grain boundaries. The source of the tellurium was thought to be contamination occurring in the casting process that became concentrated in the recycled skimmings. It was recommended that future material specifications for skimmings and for externally obtained scrap copper include a trace analysis for tellurium.
Galvanic Corrosion Failure of Austenitic Stainless Steel Pipe Flange Assemblies
Authors: Lochanski Edward C.
Published: May 2019

Catastrophic pitting corrosion occurred in type 304L stainless steel pipe flange assemblies in an industrial food processor. During regular service the pumped medium was pureed vegetables. In situ maintenance procedures included cleaning of the assemblies with a sodium hypochlorite solution. It was determined that the assemblies failed due to an austenite-martensite galvanic couple activated by a chlorine bearing electrolyte. The martensitic areas resulted from a transformation during cold-forming operations. Solution annealing after forming, revision of the design of the pipe flange assemblies to eliminate the forming operation, and removal of the source of chlorine were recommended.
Leaks in Copper Tubing From Cooling Coils of a Large Air-Conditioning Unit
Authors: Edwards J.O. , Hamilton R.I.
Published: May 2019

Copper tubes from the cooler assemblies of a large air-conditioning unit exhibited leakage upon installation of the unit. Sections from two leaking tubes and one nonleaking tube were subjected to pressure testing and microscopic examination. The cause of leaking was determined to be pitting corrosion. Extensive pitting was found on the insides of all sections examined, with deep and numerous pits in leaking areas. Circumstantial evidence indicated that antifreeze solution left in the tubes from the manufacturing operation was the most likely cause of the pitting.
Short-Term Failure of Carbon Steel Boiler Tubes
Authors: Bigelow Clifford C.
Published: May 2019

Two identical “D” tube package boilers, installed at separate plants, experienced a number of tube ruptures after relatively short operating times. The tubes, which are joined by membranes, experienced localized bulging and circumferential cracking along the fireside crown as a result of overheating and thermal fatigue. It was recommended that recent alterations to the steam-drum baffling be remodified to improve circulation in the boiler and prevent further overheating. Several thermocouples were attached to tubes in problem areas of the boiler to monitor the effects of the steam-drum modifications on tube wall temperatures.
Stress-Corrosion Cracking in a Stainless Steel Emergency Injection Pipe in a Nuclear Reactor
Authors: Muraleedharan P. , Gnanamoorthy J.B.
Published: May 2019

A section of type 304 stainless steel pipe from a stand by system used for emergency injection of cooling water to a nuclear reactor failed during precommissioning. Leaking occurred in only one spot. Liquid penetrant testing revealed a narrow circumferential crack. Metallographic examination of the cracked area indicated stress-corrosion cracking, which had originated at rusted areas that had formed on longitudinal scratch marks on the outer surface of the pipe. The material was free from sensitization, and there was no significant amount of cold work. It was recommended that the stainless steel be kept rust free.
Failure of a Reversible Flap Valve in a Thermal Power Station
Authors: Vasu K.K.
Published: May 2019

A reversible four-way carbon steel flap valve in a thermal power station failed after 7 years of service. The flap had been fabricated by welding two carbon steel plates to both sides of a carbon steel forging. The valve was used for reversing the flow direction of seawater in the cooling system of a condenser. Visual examination of the flap showed crystalline fracture, indicating a brittle failure. Metallographic examination, chemical analyses, and tensile and impact testing indicated that the failure was caused by the notch sensitivity of the forging material, which resulted in low toughness. It was recommended that fully killed carbon steel with a fine-grain microstructure be used. Redesign of the flap to remove the step in the forging that acted as a notch was also recommended.
Aluminum/Refrigerant Reaction Resulting in the Failure of a Centrifugal Compressor
Authors: Studer Anthony C.
Published: May 2019

An investigation of the impeller and deposit samples from a centrifugal compressor revealed that an aluminum IR-12 refrigerant reaction had occurred, causing extensive damage to the second-stage impeller and contaminating the internal compressor components. The spherical surface morphology of the impeller fragments suggested that the aluminum had melted and resolidified. The deposits were similar in composition and were identified by XRD as consisting primarily of aluminum trifluoride. In addition, EDS analysis detected major amounts of chlorine and iron. Results of a combustion test indicated that the compressor deposit was comprised of a 9. 8 wt% carbon and that the condenser deposit contained 8.7 wt% carbon. It was concluded that the primary cause of failure was the rubbing of the impeller against the casting and that a self-sustaining Freon fire had occurred in the failed compressor
Failure Analysis of a Hydroturbine Shaft
Authors: McCann Donald R. , Harry Michael V.
Published: May 2019

A forged 4140 steel shaft that connected two runners in a hydroturbine failed catastrophically after approximately 5900 h of service. The runner and the mating section of the broken shaft were examined and tested by various methods. The results of the analyses indicated that the shaft failed by torsional fatigue starting at subsurface crack initiation sites. The forging contained regions of crack like flaws associated with particles rich in chromium, manganese, and iron. Fracture features indicated that the fatigue cracks propagated under a relatively low stress.
Dezincification of a Chrome-Plated Cylinder Gas Valve
Authors: Colwell Richard L.
Published: May 2019

Two new chrome-plated CDA 377 brass valves intended for inert gas service failed on initial installation. After a pickling operation to clean the metal, the outer surfaces of the valves had been flashed with copper and then plated with nickel and chromium for aesthetic purposes. One of the valves failed by dezincification. The porous copper matrix could not sustain the clamping loads imposed by tightening the pressure relief fitting. The second valve failed by shear overload of the pressure relief fitting. Overload was facilitated by a reduction of cross-sectional area caused by intergranular attack and slight dezincification of the inner bore surface of the fitting. Dezincification and intergranular attack were attributed to excessive exposure to nonoxidizing acids in the pickling bath.
Failure of Three Valve Body Castings
Authors: Goodrich George M.
Published: May 2019

Three sprinkler system dry pipe valve castings (class 30 gray iron), two that had failed in service and one that had been rejected during machining because of porosity, were submitted for examination. The two failures consisted of cracks in a seating face. All three were from the same heat. Visual examination showed that the casting had cracked through a thin area in the casting sidewall. Evidence of a sharply machined corner at the fracture site was also discovered. Tensile testing and metallographic analysis revealed no metallurgical cause for the failure. It was recommended that the manufacturer work with the foundry to evaluate the criticality of core placement and to eliminate the undesired thin section.
Fracture of a Spike Maul
Authors: D'Antonio Carmine
Published: May 2019

An AISI 9260 steel railroad spike maul failed after a relatively short period of service. The maul head fractured in two pieces when struck against a rail. Visual, fractographic, metallographic, and chemical analyses were conducted on sections taken from the maul head, which was found to have fractured across both sides of the eye. Failure occurred in at least three separate events: formation of two cracks immediately adjacent to the eye, extension of one of the original cracks over a portion of one of the eye sides, and abrupt extension of the original crack across the eye sides, resulting in separation into two halves.
Hydrogen-Assisted Stress Cracking of Carburized and Zinc Plated SAE Grade 8 Wheel Studs
Authors: Baggerly Roy G.
Published: May 2019

Several case-hardened and zinc-plated carbon-manganese steel wheel studs fractured in a brittle manner after very limited service life. The fracture surfaces of both front and rear studs showed no sign of fatigue beach marks or deformation in the form of shear lips that would indicate either a fatigue mechanism or ductile overload failure. SEM analysis revealed that the mode of fracture was intergranular decohesion, which indicates an environmental influence in the fracture mechanism. The primary fracture initiated at a thread root and propagated by environmentally-assisted slow crack growth until final fracture. The natural stress concentration at the thread root, when tightened to the required clamp load concomitant with the presence of cracks in the carburized case, was sufficient to exceed the critical stress intensity for hydrogen-assisted stress cracking (HASC). The zinc plating exacerbated the situation by providing a strong local corrosion cell in the form of a sacrificial anode region adjacent to the cracked thread. The enhanced generation of hydrogen in a corrosive environment subsequently lead to HASC of the wheel studs.
Corrosion Fatigue Failure of Stainless Steel Load Cells in a Milk Storage Tank
Authors: Collins Daryl C.
Published: May 2019

Two type 420 martensitic stainless steel load cell bodies, which had been installed under two of the four legs of a milk storage tank failed in service. The failure occurred near a change in section and involved fracture of the entire cross section. Examination showed a brittle fracture that was preceded by a small fatigue region. Pitting corrosion was evident at the fracture origin. The areas around the load cells had been subjected to regular washdowns using high-pressure hot water, and the pitting was attributed to crevice corrosion between the load cell and the holddown bolts. Prevention of such corrosion by the use of a flexible sealant to eliminate the crevice was recommended.
Formation of Refractory Films on Metal Contacts in an Electrical Switchgear
Authors: Hopkins John R.
Published: May 2019

During routine quality control testing, small circuit breakers exhibited high contact resistance and, in some cases, insulation of the contacts by a surface film. The contacts were made of silver-refractory (tungsten or molybdenum) alloys. Infrared analysis revealed the film to be a corrosion layer that resulted from exposure to ammonia in a humid atmosphere. Simulation tests confirmed that ammonia was the corrodent. The ammonia originated from the phenolic molding area of the plant. It was recommended that fumes from molding areas be vented outside the plant and that assembly, storage, and calibration areas be isolated from molding areas.
Stress-Corrosion Cracking in Stainless Steel Heater Sheathing
Authors: Muraleedharan P. , Khatak H.S. , Gnanamoorthy J.B.
Published: May 2019

Cracking occurred in type 304L stainless steel sheaths on nichrome wire heaters that had been in storage for about 5 years in a coastal atmosphere. The cracks were discovered when the heater coils were removed from storage in their original polyethylene packing materials and straightened for use. Fractography established that fracture occurred by stress-corrosion cracking. The cracks originated at rusted areas on the cladding that occurred under iron particles left on the surface during manufacture. High hardness values indicated that solution annealing following cold working had not been carried out as specified. It was recommended that the sheathing material be fully annealed and that the outer surface be pickled and passivated.
EVALUASI KESIAPAN GURU FISIKA SMA DALAM KEGIATAN LABORATORIUM DI KOTA MATARAM
Authors: Isnaini M , Anwar Kharil
Published: May 2019

Tujuan penelitian ini adalah untuk mengetahui kesiapan guru fisika SMA dalam kegiatan laboratorium. Kesiapan guru fisika SMA dalam kegiatan laboratorium dapat diketahui dari: (1) kompetensi laboratorium guru fisika SMA dalam merancang kegiatan laboratorium; (2) sarana prasarana laboratorium; (3) hambatan-hambatan yang ditemui guru fisika SMA dalam melaksanakan kegiatan laboratorium; dan (4) langkah-langkah guru fisika SMA mengatasi hambatan dalam melaksanakan kegiatan laboratorium, sehingga hasil temuan ini dapat digunakan sebagai masukan bagi: (1) guru fisika SMA untuk meningkatkan kompetensinya dalam kegiatan laboratorium; (2) Kemendikbud, Dinas Dikpora Kota Mataram dan Provinsi NTB untuk meningkatkan kompetensi kegiatan laboratorium guru fisika SMA melalui pelatihan-pelatihan tentang laboratorium; (3) Lembaga Pendidik Tenaga Keguruan (LPTK) diharapkan meningkatkan kualitas lulusan calon guru fisika dalam kegiatan laboratorium. Penelitian ini menggunakan pendekatan deskriptif kualitatif dengan metode pengumulan data berupa dokumentasi, angket, wawancara dan observasi. Populasi penelitian ini adalah guru fisika  SMA se-Kota Mataram yang terdiri dari 8 SMA Negeri dan  10 SMA Swasta berjumlah 32 orang. Sampel penelitian adalah 20 orang guru fisika SMA se-Kota Mataram yang terdiri dari 14 guru SMAN, 6 guru SMA Swasta. Ke-20 guru sampel tersebar di 7 SMA Negeri dan 6 SMA Swasta. Berdasarkan informasi dan analisis yang dilakukan kesiapan guru fisika kota mataram dalam kegiatan laboratorium dikategorikan cukup siap, yang dapat dilihat dari: (a) kompetensi guru fisika SMA dalam kegiatanlaboratorium cukup baik, yaitu sebesar 52%, (b) Kondisi sarana prasarana laboratorium fisika kategori cukupbaik, yaitu sebesar 63.1%, (c) Faktor penghambat kegiatan laboratorium berupa gedung/ruangan sebesar56% dalam ketegori cukup banyak, pengelolaan laboratorium sebesar 70% berkategori cukup banyak,  dan alat dan bahan kegiatan laboratorium, sebesar 56% berkategori cukup banyak, dan (d) Langkah-langkah dalam mengatasi hambatan kegiatan laboratorium gedung/ruang laboratorium dikategorikan cukup baik,yaitu sebesar 70%, pengelolaan laboratorium berkategori cukup baik, sebesar 57% dan alat dan bahan kegiatanlaboratorium sebesar 58%, dalam ketegori cukup baik. Saran yang dapat diberikan dari hasil penelitian ini adalah diharapkan agar instansi terkait lebih sering memberikan pelatihan terhadap kegiatan laboarotium  untuk meningkatkan kompetensi guru dalam kegiatan laboratorium khususnya kegiatan prosedur percobaan  inquiri atau keterampilan proses dan alat evaluasi kegiatan laboratorium.
MENINGKATKAN KUALITAS PEMBELAJARAN SEJARAH ASIA TIMUR MELALUI PENERAPAN METODE INKUIRI DI JURUSAN PENDIDIKAN SEJARAH FKIP UM MATARAM
Authors: Afandi Ahmad
Published: May 2019

Penelitian ini bertujuan untuk meningkatkan kualitas pembelajaran mata kuliah Sejarah Asia Timur di Program Studi Pendidikan Sejarah Fakuktas Keguruan dan Ilmu Pendidikan Universitas Muhammadiyah Mataram, melalui penerapan dan pengembangan model inkuiri. Pengembangan model ini dilatarbelakangi oleh perlunya dinamisasi dalam proses pembelajaran, sehingga dapat menghasilkan pembelajaran bermakna. Meningkatkan kualitas pembelajaran mahasiswa dalam pengertian mencari, menemukan, dan memecahkan permasalahan dalam perkuliahan dengan penerapan metode inkuiri, yang pada dasarnya juga merupakan penerapan metode sejarah kritis yakni: heuristik, kritik, interpretasi, dan historiografi. Metode yang digunakan dalam penelitian ini  adalah penelitian kualitatif dengan strategi kaji tindak berbasis kelas atau penelitian tindakan kelas. Pemilihan metodeini berdasarkan asumsi bahwa perbaikan proses kegiatan pembelajarandi dalam kelas dapat dilaksanakan pengajar dengan melakukan refleksi tentang berbagai hal yang telah  dilakukan dalam proses kegiatan pembelajaran, seperti penentuan tujuan pembelajaran, penyusunan materi ajar, sumber buku acuan yang digunakan, strategi pembelajarannya, alokasi waktu yang digunakan dan evaluasi. Aktivitas pengimplementasian tujuan penelitian ini dilakukan dengan pendekatan partisipatif kolaboratif antara pimpinan program, dosen, dan peneliti, sehingga terjadi sharing dalam penyusunan perencanaan tindakan. Hasil penelitian ini menunjukkan bahwa terjadi peningkatan kualitas pembelajaran pada mahasiswa semester III Program Studi Pendidikan Sejarah Fakuktas Keguruan dan Ilmu Pendidikan Universitas Muhammadiyah Mataram melaluipengembangan dan penerapan model inkuiri. Strategi inkuiri yang diterapkan diawali dengan strategi ekspositori yang menempatkan peranan besar dosen dalam pembelajaran terutama dalam hal membina, mengarahkan, membimbing, memberi tindakan, dan mengevaluasi serta refleksi, dan diakhiri dengan strategi inkuiri yangmenuntut kemandirian mahasiswa dalam proses mencari, menemukan, dan memecahkan permasalahan yang berkaitan dengan masalah-masalah yang diajukan oleh dosen. Oleh karena itu, penelitian inikuiri ini tepat jikadesebut sebagai model inkuiri terpimpin.
AN ANALYSIS OF ERRORS ON THE USING SIMPLE PAST IN WRITING A NARRATIVE TEXT
Authors: Umar Umar
Published: May 2019

This study aimed to examine errors on past tense in a writing a narrative text of by 12 participants. The participantswere second semester students of English Education Department of STKIP Paracendekia NW Sumbawa in theacademic year 2014/2015. This research was a descriptive qualitative research. The instrument used for this studywas participants’ written narrative texts. The results of the study show that there were errors committed by theparticipants on using past tense. All of the errors on using past tense in the written narrative texts was identified andclassified; these were addition, omission, and misformation.These aspects of writing in English pose the most difficultproblems to participants. This study has shed light on the manner in which students internalize the rules of the targetlanguage, which is English. Such an insight into language learning problems is useful to lecturers because it providesinformation on common trouble-spots in language learning which can be used in the preparation of effective teachingmaterials.
PENINGKATAN SIKAP TERHADAP SAINS MELALUI MODEL PEMBELAJARAN INQUIRY DENGAN PENGGUNAAN TOSRA TERHADAP PEMBELAJARAN IPA DI SMP NEGERI 6 MATARAM
Authors: Usmiatiningsih Ellysabeth
Published: May 2019

Penelitian ini dilatarbelakangi oleh adanya sikap negatif siswa pada materi IPA yang bersifat virtual sehingga mengakibatkan materi IPA sulit dipelajari. Subyek penelitian tindakan kelas yaitu kelas VIIIE berjumlah 26 siswa yang memiliki karakter meremehkan pelajaran IPA, tidak senang belajar IPA sehingga pada materi tertentu memilikinilai rendah. Materi yang digunakan dalam penelitian adalah cahaya karena cakupan materi yang cukup luas dengankriteria ketuntasan minimal (KKM) 77. Penelitian ini dilaksanakan 3 siklus dengan menggunakan modelpembelajaran inquiry yang bertujuan untuk meningkatkan sikap terhadap sains siswa. Hasil Penelitian tindakan kelasyaitu terjadi peningkatan sikap terhadap sains sebesar 19,04%, peningkatan sikap siswa selama diskusi sebesar21,75%, peningkatan skor rata-rata diskusi siswa sebesar 26,53, peningkatan keterlaksanaan KBM sebesar 5,6%.Maka dalam peneltian tindakan kelas ini dapat disimpulkan bahwa penerapan model inquiry dapat meningkatkansikap terhadap sains siswa.
PENINGKATAN KINERJA GURU DALAM MELAKSANAKAN PENILAIAN BERBASIS KELAS MELALUI SUPERVISI AKADEMIK KEPALA SEKOLAH DI SDN BEBIE
Authors: Muhadis Muhadis
Published: May 2019

Abstrak: Tujuan diadakan Penelitian untuk mengetahui sejauh mana peningkatan kinerja guru dalam melaksanakan penilaian berbasis kelas melalui supervisi akademik Pengawas di SDN Bebie Kec.Praya  Kab. Lombok Tengah tahun pelajaran 2016/2017. Hasil nilai 68,88 pada siklus l dengan prosentase kinerja guru secara kelompok/klasikal 37,5%, dapat meningkat pada siklus 2 menjadi 80,63 dengan prosentase kinerja guru secara kelompok/klasikal 100% sudah melebihi dari standar 85%. disimpulkan bahwa penerapan supervisi akademik Kepala Sekolah dapat meningkatkan kinerja guru dengan ketuntasan kelompok/kalsikal mencapai 100 %, dengan demikian penerapan supervisi akademik Kepala Sekolah efektif meningkatkan kinerja guru dalam melaksanakan penilaian berbasis kelas di SDN Bebie Lombok Tengah.Abstract:  The purpose of this study to determine the extent to which improvements in teacher performance in implementing classroom-based assessment through supervision supervision supervision at SDN Bebie District Praya Central Lombok Tengah academic year 2016/2017. The result of score 68,88 in cycle 1 with the percentage of teacher performance in group / classical 37,5%, can increase in cycle 2 to 80,63 with the percentage of teacher performance in group / classical 100% already exceed from standard 85%. it is concluded that the application of academic supervision of principal can improve teacher performance with group / classical completeness reach 100%, thereby applying of principal academic supervision effectively improve teacher performance in carrying out class-based assessment at SDN Bebie Lombok Tengah.
IMPLEMENTASI METODE MIND MAPPING UNTUK MENINGKATKAN MINAT DAN KOMPETENSI WRITING SISWA KELAS VII D SMPN 5 KOPANG
Authors: Abdul Gani Ruslan
Published: May 2019

Abstrak: Penelitian Tindakan Kelas dilakukan 2 siklus terhadap kelas VII D SMPN 5 Kopang tahun 2014/2015, menggunakan metode pengumpulan data Observasi, Interview, dan dokumentasi, serta tes tentang peningkatan kompetensi dan prestasi writing siswa.. diperoleh nilai rata-rata prestasi dan kompetensi writing bahwa ketuntasan klasikal pada siklus I 89%. Sedangkan pada siklus II terjadi peningkatan ketuntasan klasikal sebesar 6% menjadi 95 %. Disimpulkan bahwa penerapan  metode mind mapping dapat meningkatkan minat dan kompetensi writing siswa pada pembelajaran procedure text kelas VII-D SMP Negeri 5 Kopang tahun pelajaran 2014/2015. Abstract: Classroom Action Research conducted 2 cycles to class VII D SMPN 5 Kopang year 2014/2015, using Observation data collection method, Interview, and documentation, and test about improving competence and writing achievement of student .. obtained by average value of achievement and competence writing that classical completeness in cycle I 89%. While in cycle II there is increase of classical mastery by 6% to 95%. It was concluded that the application of mind mapping method can increase interest and writing competence of students on learning text procedure of class VII-D of SMP Negeri 5 Kopang for academic year 2014/2015.
Pengaruh Kualitas Pelayanan Dan Kualitas Produk Terhadap Keputusan Pembelian Konsumen Pada Toko Amanda Brownies
Authors: Br Situmorang Evinda Deviana , Gultom Robinhot , Nadapdap Kristanty , Sihite Mislan
Published: May 2019

This study aims to determine the influence of service quality and product quality on consumer purchase decision at Amanda Brownies Store in Medan. The population of this study was taken from the number of consumers for 6 month totalling 1,509 or 252 consumers in a month. The number of samples taken in this study was 155 consumers. The data collection methods in this study used questionnaires among 155 consumers of Amanda Brownies Store in Medan. The data analysis method used was Multiple Linear Regression method. The partial testing analysis shows that service quality and product quality have a significant effect on consumer purchase decision. Furthermore, the simultaneous test results showed that the service quality variable and product quality variable significantly influence the consumer purchase decision. The Adjusted R Square is 0.316 or 31.6%. This means that 31.6% of consumer purchase decision is influenced by both independent variables, while the remaining 68.4% of customer purchase decision is influenced by other variables-not examined in this study.