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Cracking in a Gray-Iron Cylinder Head Caused by Microporosity 微孔隙引起灰铸铁缸盖开裂
ASM Failure Analysis Case Histories: Automobiles and Trucks Pub Date : 2019-06-01 DOI: 10.31399/asm.fach.auto.c0089526
{"title":"Cracking in a Gray-Iron Cylinder Head Caused by Microporosity","authors":"","doi":"10.31399/asm.fach.auto.c0089526","DOIUrl":"https://doi.org/10.31399/asm.fach.auto.c0089526","url":null,"abstract":"\u0000 A gray iron cylinder head cracked after approximately 16,000 km of service. The head was cracked on the rocker arm pan rail next to the No. 3 intake port and extended into the water jacket on the rocker-arm side of the head. Microporosity was revealed in the crack in the sections taken from the water jacket next to the plug and the area next to the No. 3 intake port. A wave of microporosity travels midway between the inner and outer surfaces of the casting was observed and was concluded to have caused the cracking. The reasons and remedies for shrinkage porosity were discussed. Controlled pouring temperatures, improved design and use of chills were recommended to avoid the casting defects.","PeriodicalId":235345,"journal":{"name":"ASM Failure Analysis Case Histories: Automobiles and Trucks","volume":"115 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116017922","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Fatigue Fracture of a 15B41 Steel Connecting-Rod Cap 15B41钢连杆帽的疲劳断裂
ASM Failure Analysis Case Histories: Automobiles and Trucks Pub Date : 2019-06-01 DOI: 10.31399/asm.fach.auto.c0046182
{"title":"Fatigue Fracture of a 15B41 Steel Connecting-Rod Cap","authors":"","doi":"10.31399/asm.fach.auto.c0046182","DOIUrl":"https://doi.org/10.31399/asm.fach.auto.c0046182","url":null,"abstract":"\u0000 A connecting cap from a truck engine fractured after 65,200 km (40,500 mi) of normal service. The cap was made from a 15B41 steel forging and was hardened to 29 to 35 HRC. Visual examination of the fracture surface disclosed an open forging defect across one of the outer corners of the cap. The defect extended approximately 9.5 mm (3/8 in.) along the side of the cap. The fracture surface exhibited beach marks typical of fatigue. The surface of the defect was stained, indicating that oxidation occurred either in heat treatment or in heating during forging. Deep etching of the fracture surface revealed grain flow normal for this type of forging, but no visible defects. 400x metallographic examination of a section through the fracture surface showed that the microstructure was an acceptable tempered martensite. However, oxide inclusions were present at the fracture surface. This evidence supported the conclusion that fatigue fracture initiated at a corner of the cap from a forging defect that extended to the surface. Fatigue cracking was propagated by cyclic loading inherent in the part. Recommendations included more careful fluorescent magnetic-particle inspection of the forged surfaces before machining and before putting the part into service.","PeriodicalId":235345,"journal":{"name":"ASM Failure Analysis Case Histories: Automobiles and Trucks","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115507096","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Cracking of Poly(butylene terephthalate) Automotive Sleeves 聚对苯二甲酸丁二酯汽车套筒的开裂
ASM Failure Analysis Case Histories: Automobiles and Trucks Pub Date : 2019-06-01 DOI: 10.31399/asm.fach.auto.c0090442
{"title":"Cracking of Poly(butylene terephthalate) Automotive Sleeves","authors":"","doi":"10.31399/asm.fach.auto.c0090442","DOIUrl":"https://doi.org/10.31399/asm.fach.auto.c0090442","url":null,"abstract":"\u0000 A number of plastic sleeves used in an automotive application cracked after assembly but prior to installation into the mating components. The sleeves were specified to be injection molded from a 20% glass-fiber-reinforced polybutylene terephthalate (PBT) resin. After molding, electronic components are inserted into the sleeves, and the assembly is filled with a potting compound. Investigation of the cracked parts and some reference parts available for testing included visual inspection, micro-FTIR in the ATR mode, and analysis using DSC. Subtle spectrum differences suggested degradation of the failed part material, and the thermograms supported this. The conclusion was that the failed sleeves had cracked due to embrittlement associated with severe degradation and the corresponding molecular weight reduction. The reduction in molecular weight significantly reduced the mechanical properties of the sleeves. The cause of the degradation was not evident, but the likely source appears to be the molding operation and exposure to elevated temperature for an extended period of time.","PeriodicalId":235345,"journal":{"name":"ASM Failure Analysis Case Histories: Automobiles and Trucks","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130411301","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Discoloration of Open-Circuit Sensor Coil 开路传感器线圈变色
ASM Failure Analysis Case Histories: Automobiles and Trucks Pub Date : 2019-06-01 DOI: 10.31399/asm.fach.auto.c9001624
S. Suess
{"title":"Discoloration of Open-Circuit Sensor Coil","authors":"S. Suess","doi":"10.31399/asm.fach.auto.c9001624","DOIUrl":"https://doi.org/10.31399/asm.fach.auto.c9001624","url":null,"abstract":"\u0000 An electronic sensor coil failed continuity testing, indicating that a break was present in the polymer-coated wire. An area of the wire showed a green discoloration and the break in the wire was located in this same region. The discoloration was suspected to be an indicator of what caused the failure. SEM/EDS and FTIR results showed the break in the coil wire was associated with corrosion. The corrosion debris contained relatively high levels of sodium and chlorine, which were likely in the form of salt. Some salt deposits were noted also in other areas along the wire surface. The findings suggested salt or salt water had leaked into the sensor and caused localized corrosion to the wire, possibly at an area where preexisting damage was present in the coating. Separation occurred in the wire when the current density at the reduced cross section caused excessive localized heating, which led to melting of the wire.","PeriodicalId":235345,"journal":{"name":"ASM Failure Analysis Case Histories: Automobiles and Trucks","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127235986","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Fretting Failure of Raceways on 52100 Steel Rings of an Automotive Front- Wheel Bearing 某汽车前轮轴承52100钢环上滚道的微动失效
ASM Failure Analysis Case Histories: Automobiles and Trucks Pub Date : 2019-06-01 DOI: 10.31399/asm.fach.auto.c0091893
{"title":"Fretting Failure of Raceways on 52100 Steel Rings of an Automotive Front- Wheel Bearing","authors":"","doi":"10.31399/asm.fach.auto.c0091893","DOIUrl":"https://doi.org/10.31399/asm.fach.auto.c0091893","url":null,"abstract":"\u0000 An automotive front-wheel outer angular-contact ball bearing generated considerable noise shortly after delivery of the vehicle. The inner and outer rings were made of seamless cold-drawn 52100 steel tubing, the balls were forged from 52100 steel, and the retainer was stamped from 1008 steel strip. The inner ring, outer ring, and balls were austenitized at 845 deg C (about 1550 deg F), oil quenched, and tempered to a hardness of 60 to 64 HRC. Investigation (visual inspection) supported the conclusion that failure was caused by fretting due to vibration of the stationary vehicle position without bearing rotation. Recommendations included improving methods of securing the vehicle during transportation to eliminate vibrations.","PeriodicalId":235345,"journal":{"name":"ASM Failure Analysis Case Histories: Automobiles and Trucks","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129711685","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Fatigue Fracture of Modified 1035 Steel Cap Screws 改进1035钢帽螺钉的疲劳断裂
ASM Failure Analysis Case Histories: Automobiles and Trucks Pub Date : 2019-06-01 DOI: 10.31399/asm.fach.auto.c0048592
{"title":"Fatigue Fracture of Modified 1035 Steel Cap Screws","authors":"","doi":"10.31399/asm.fach.auto.c0048592","DOIUrl":"https://doi.org/10.31399/asm.fach.auto.c0048592","url":null,"abstract":"\u0000 A drive-line assembly failed during vehicle testing. The vehicle had traveled 9022 km (5606 mi) before the failure occurred. Both the intact and fractured parts of the assembly were analyzed to determine the cause and sequence of failure. Visual examination of the assembly showed three of four bearing caps, two cap screws, and one universal-joint spider had fractured. Examination of the three fractured bearing caps and the spider showed no evidence of fatigue but showed that fracture occurred in a brittle manner. The bearing cap that was not destroyed still contained portions of the two fractured cap screws. It was found that the two cap screws failed in fatigue under service stresses. The three bearing caps and the universal-joint spider broke in a brittle manner. The properties of the material in the cap screws did not fulfill the specifications. The modified 1035 steel was of insufficient alloy content. Also, the tensile strength and endurance limit were lower than specified and were inadequate for the application. The material for the cap screw was changed from modified 1035 steel to 5140 steel.","PeriodicalId":235345,"journal":{"name":"ASM Failure Analysis Case Histories: Automobiles and Trucks","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114396007","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Fracture of Cast Steel Equalizer Beams 铸钢均衡梁断裂
ASM Failure Analysis Case Histories: Automobiles and Trucks Pub Date : 2019-06-01 DOI: 10.31399/asm.fach.auto.c0089572
{"title":"Fracture of Cast Steel Equalizer Beams","authors":"","doi":"10.31399/asm.fach.auto.c0089572","DOIUrl":"https://doi.org/10.31399/asm.fach.auto.c0089572","url":null,"abstract":"\u0000 Two sand-cast low-alloy steel equalizer beams (ASTM A 148, grade 105-85) designed to distribute the load to the axles of a highway truck broke after an unreported length of service. Normal service life would have been about 805,000 km (500,000 mi) of truck operation. Investigation (visual inspection, chemical analysis, tensile testing, unetched 65x and 1% nital etched 65x magnification) supported the conclusions that the steel was too soft for the application – probably due to improper heat treatment. Fracture of the equalizer beams resulted from growth of mechanical cracks that were formed before the castings were heat treated. Recommendations included the following changes in processing: better gating and risering in the foundry to achieve sounder castings; better shakeout practice to avoid mechanical damage; better inspection to detect imperfections; and normalizing and tempering to achieve better mechanical properties.","PeriodicalId":235345,"journal":{"name":"ASM Failure Analysis Case Histories: Automobiles and Trucks","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133805620","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Failure Analysis of Door Lock Assemblies Illustrating the Statistical Aspects of Failure Analysis 门锁组件的失效分析，说明失效分析的统计方面
ASM Failure Analysis Case Histories: Automobiles and Trucks Pub Date : 2019-06-01 DOI: 10.31399/asm.fach.auto.c9001732
J. Forgione
{"title":"Failure Analysis of Door Lock Assemblies Illustrating the Statistical Aspects of Failure Analysis","authors":"J. Forgione","doi":"10.31399/asm.fach.auto.c9001732","DOIUrl":"https://doi.org/10.31399/asm.fach.auto.c9001732","url":null,"abstract":"\u0000 Statistical techniques provide the design engineer with a powerful tool for the analysis of failure data. By means of an actual case study, steps required to design a test yielding statistically meaningful data and procedures used in graphical analysis of results are presented. The Weibull distribution is the statistical model used as a basis for these techniques. This method of failure analysis provides the engineer with clear, positive design direction.","PeriodicalId":235345,"journal":{"name":"ASM Failure Analysis Case Histories: Automobiles and Trucks","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125701886","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Contact Fatigue Failure of an Axle Shaft Spur Pinion 车轴直齿小齿轮的接触疲劳失效
ASM Failure Analysis Case Histories: Automobiles and Trucks Pub Date : 2019-06-01 DOI: 10.31399/asm.fach.auto.c9001498
Lester E. Alban
{"title":"Contact Fatigue Failure of an Axle Shaft Spur Pinion","authors":"Lester E. Alban","doi":"10.31399/asm.fach.auto.c9001498","DOIUrl":"https://doi.org/10.31399/asm.fach.auto.c9001498","url":null,"abstract":"\u0000 One end of an axle shaft containing the integral spur pinion was submitted for examination, along with the report of a tooth pitting failure. The spur pinion, integral to the axle shaft, operated in a medium-size, off-highway truck at an open-pit mine, for “a relatively short time.” Only the pinion head had been returned. The shaft portion had been torch-cut away. Chemical analysis along with the microstructure confirmed the specified material was SAE 43BV12 Ni-Cr-Mo alloy steel. The mode of failure was surface contact fatigue through the shear plane subsurface at the lowest point of single-tooth contact. The cause of failure was tooth-tip interference from the mating gear teeth. Because the mating parts within the assembly had not been returned or examined, unanswered questions remained.","PeriodicalId":235345,"journal":{"name":"ASM Failure Analysis Case Histories: Automobiles and Trucks","volume":"323 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124296819","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Failure of Polyethylene Terephthalate Assemblies 聚对苯二甲酸乙二醇酯组件失效
ASM Failure Analysis Case Histories: Automobiles and Trucks Pub Date : 2019-06-01 DOI: 10.31399/asm.fach.auto.c0090451
{"title":"Failure of Polyethylene Terephthalate Assemblies","authors":"","doi":"10.31399/asm.fach.auto.c0090451","DOIUrl":"https://doi.org/10.31399/asm.fach.auto.c0090451","url":null,"abstract":"\u0000 Cracking occurred within the plastic jacket (injection molded from an impact-modified, 15% glass-fiber-reinforced PET resin.) of several assemblies used in a transportation application during an engineering testing regimen which involved cyclic thermal shock (exposing the parts to alternating temperatures of -40 and 180 deg C (-40 and 360 deg F)). Prior to molding, the resin had reportedly been dried at 135 deg C (275 deg F). The drying process usually lasted 6 h, but occasionally, the material was dried overnight. Comparison investigation (visual inspection, 20x SEM views, micro-FTIR, and analysis using DSC and TGA) with non-failed parts supported the conclusion that that the failure was via brittle fracture associated with the exertion of stresses that exceeded the strength of the resin as-molded caused by the disparity in the CTEs of the PET jacket and the mating steel sleeve. The drying process had exposed the resin to relatively high temperatures, which caused substantial molecular degradation, thus limiting the part's ability to withstand the stresses. The drying temperature was found to be significantly higher than the recommendation for the PET resin, and the testing itself exposed the parts to temperatures above the recognized limits for PET.","PeriodicalId":235345,"journal":{"name":"ASM Failure Analysis Case Histories: Automobiles and Trucks","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130476787","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
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