ASM Failure Analysis Case Histories: Failure Modes and Mechanisms最新文献_第2页

Stress-Corrosion Cracking of a Brass Radiator Coil 黄铜散热器盘管的应力腐蚀开裂

ASM Failure Analysis Case Histories: Failure Modes and Mechanisms Pub Date : 2019-06-01 DOI: 10.31399/asm.fach.modes.c9001012

P. Ogden

{"title":"Stress-Corrosion Cracking of a Brass Radiator Coil","authors":"P. Ogden","doi":"10.31399/asm.fach.modes.c9001012","DOIUrl":"https://doi.org/10.31399/asm.fach.modes.c9001012","url":null,"abstract":"\u0000 An interstage radiator gas coil began leaking after only 45 days of service. The original brass coil with several aluminum fins was replaced three times but each replacement lasted less than a day. After removing the fins, leaks were found at circumferential cracks. A section of a tube was removed and split, revealing a series of cracks, evenly spaced. Crack spacing coincided with fin spacing, indicating that stresses incurred during installation of the fins promoted failure. Metallographic examination showed intergranular, branched cracking, characteristic of stress corrosion failures, with the cracks starting on the inside surfaces of the tubes. There was no known corrosive agent in the system, and no other corrosion damage could be found. Qualitative tests and spectrographic analysis gave a positive indication for mercury. The spacing of the cracks, the branched intergranular cracking, the rapid failure, and presence of mercury led to the conclusion of stress-corrosion cracking. It was impossible to remove mercury from the system so carbon steel coils were substituted for the brass ones. The carbon steel coils gave failure-free service for over nine years.","PeriodicalId":231268,"journal":{"name":"ASM Failure Analysis Case Histories: Failure Modes and Mechanisms","volume":"108 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":"131062946","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

Electron Fractography Pinpoints Cause of Fatigue Fracture 电子断口分析指出疲劳断裂的原因

ASM Failure Analysis Case Histories: Failure Modes and Mechanisms Pub Date : 2019-06-01 DOI: 10.31399/asm.fach.modes.c9001537

E. A. Lauchner, R. E. Herfert

{"title":"Electron Fractography Pinpoints Cause of Fatigue Fracture","authors":"E. A. Lauchner, R. E. Herfert","doi":"10.31399/asm.fach.modes.c9001537","DOIUrl":"https://doi.org/10.31399/asm.fach.modes.c9001537","url":null,"abstract":"\u0000 After completing a fatigue test of an aluminum alloy component machined from a 7079-T6 forging, technicians noted a 5 in. crack which ran longitudinally above and through the flange. When the fracture face was examined by light microscopy, observers could not ascertain the exact mode of fracture. Electron fractography revealed that five different modes of crack growth were operative as the part failed. Region 1 was a shallow zone (about 0.002 in. at its deepest) of dimpled structure typical of an overload failure. Region 2 was a zone that grew by a stress corrosion mechanism. Through a fatigue mechanism was operative in Region 3, it was not the cause of the large crack. Region 4, which covered 50% of the fracture area, developed mainly by stress corrosion. This zone gradually changed into the combination of intergranular and transgranular overload in Region 5, which covered approximately the remaining 50% of the fracture. Apparently, after stress corrosion moved halfway through, the part failed by overload. This failure analysis proved that a crack, originally thought to be a fatigue failure, was actually a stress corrosion crack.","PeriodicalId":231268,"journal":{"name":"ASM Failure Analysis Case Histories: Failure Modes and Mechanisms","volume":"70 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":"114710763","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

Corrosion of a Ballast Gas Elbow Assembly 镇流器气体弯头组件腐蚀

ASM Failure Analysis Case Histories: Failure Modes and Mechanisms Pub Date : 2019-06-01 DOI: 10.31399/asm.fach.modes.c0006417

{"title":"Corrosion of a Ballast Gas Elbow Assembly","authors":"","doi":"10.31399/asm.fach.modes.c0006417","DOIUrl":"https://doi.org/10.31399/asm.fach.modes.c0006417","url":null,"abstract":"\u0000 A cadmium-plated 4340 Ni-Cr-Mo steel ballast elbow assembly was submitted for failure analysis to determine the element or radical present in an oxidation product found inside the elbow assembly. Energy-dispersive x-ray analysis in the SEM showed that iron was the predominant species, presumably in an oxide form. The inside surface had the appearance of typical corrosion products. Hardness measurements indicated that the 4340 steel was heat treated to a strength of approximately 862 MPa (125 ksi). It was concluded that the oxide detected on the ballast elbow was iron oxide. The possibility that the corrosion products would eventually create a blockage of the affected hole was great considering the small hole diameter (4.2 mm, or 0.165 in.). It was recommended that a quick fix to stop the corrosion would be to apply a corrosion inhibitor inside the hole. This, however, would cause the possibility of inhibitor buildup and the eventual clogging of the hole. A change in the manufacturing process to include a cadmium plating on the hole inside surface was recommended. This was to be accomplished in accordance with MIL specification QQ-P-416, Type II, Class 1. A material change to 300-series stainless steel was also recommended.","PeriodicalId":231268,"journal":{"name":"ASM Failure Analysis Case Histories: Failure Modes and Mechanisms","volume":"130 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":"116887851","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 a Gray Iron Pump Bowl Because of Graphitic Corrosion from Exposure to Well Water 灰铸铁泵碗暴露在井水中石墨腐蚀导致的故障

ASM Failure Analysis Case Histories: Failure Modes and Mechanisms Pub Date : 2019-06-01 DOI: 10.31399/asm.fach.modes.c0047332

引用次数: 0

Failure of a Large Gas Cylinder Due to Internal Laminar Defects 某大型气瓶因内部层流缺陷而失效

ASM Failure Analysis Case Histories: Failure Modes and Mechanisms Pub Date : 2019-06-01 DOI: 10.31399/asm.fach.modes.c9001446

引用次数: 0

Failure of Rifle Receivers Caused by Exfoliation 来复枪接收机脱落导致的故障

ASM Failure Analysis Case Histories: Failure Modes and Mechanisms Pub Date : 2019-06-01 DOI: 10.31399/asm.fach.modes.c0047199

{"title":"Failure of Rifle Receivers Caused by Exfoliation","authors":"","doi":"10.31399/asm.fach.modes.c0047199","DOIUrl":"https://doi.org/10.31399/asm.fach.modes.c0047199","url":null,"abstract":"\u0000 The lower receiver of the M16 rifle is an anodized forging of aluminum alloy 7075-T6. Degradation of the receivers was observed after three years of service in a hot, humid atmosphere. The affected areas were those in frequent contact with the user's hands. There was no question that the material failed as a result of exfoliation corrosion, so an investigation was undertaken, centered around the study of thermal treatments that would increase the exfoliation resistance and still develop the required 448 MPa (65 ksi) yield strength. The results of the study concluded that rolled bar stock should be preferred to extruded bar stock. Differences in grain structure of the forgings, as induced by differences in thermal-mechanical history of the forged material, can have a significant effect on susceptibility to exfoliation corrosion. Regarding thermal treatment, the results show conclusively that large changes in strength and exfoliation characteristics of 7075 forgings can be induced by changes in temperature or time of thermal treatment. With regard to the effect of quenching rate on exfoliation characteristics, a cold-water quench below 25 deg C (75 deg F) would appear to be far superior to an elevated-temperature quench to minimize exfoliation for 7075 forgings in the T6 temper.","PeriodicalId":231268,"journal":{"name":"ASM Failure Analysis Case Histories: Failure Modes and Mechanisms","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":"129915412","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 a Polyoxymethylene Gear Wheel 聚氧亚甲基齿轮失效

ASM Failure Analysis Case Histories: Failure Modes and Mechanisms Pub Date : 2019-06-01 DOI: 10.31399/asm.fach.modes.c0092103

引用次数: 0

Failure of a Nylon Driving Gear 尼龙传动装置故障

ASM Failure Analysis Case Histories: Failure Modes and Mechanisms Pub Date : 2019-06-01 DOI: 10.31399/asm.fach.modes.c0092102

引用次数: 0

Leaky Heating Coils of an Austenitic Chromium-Nickel-Molybdenum Steel 奥氏体铬镍钼钢的漏热盘管

ASM Failure Analysis Case Histories: Failure Modes and Mechanisms Pub Date : 2019-06-01 DOI: 10.31399/asm.fach.modes.c9001177

F. Naumann, F. Spies

引用次数: 0

Failure of an Incoloy 800 Piping System 铬合金800管道系统故障

ASM Failure Analysis Case Histories: Failure Modes and Mechanisms Pub Date : 2019-06-01 DOI: 10.31399/asm.fach.modes.c0046991

{"title":"Failure of an Incoloy 800 Piping System","authors":"","doi":"10.31399/asm.fach.modes.c0046991","DOIUrl":"https://doi.org/10.31399/asm.fach.modes.c0046991","url":null,"abstract":"\u0000 The outlet-piping system of a steam-reformer unit failed by extensive cracking at four weld locations. The welded system consisted of Incoloy 800 (Fe-32Ni-21Cr-0.05C) pipe and fittings. The exterior surfaces of the system were insulated with rock wool that did not contain weatherproofing. On-site visual examination and magnetic testing indicated severe external corrosion of most of the piping. The system showed extensive cracking in weld HAZ. One specimen indicated that corrosion extended to a depth of 3.2 mm and cracks were seen at the edge of the cover bead and in the HAZ of the weld. Metallographic examination showed that cracking was intergranular and that adjacent grain boundaries had undergone deep intergranular attack. Examination at higher magnification revealed heavy carbide precipitation, primarily at grain boundaries, indicating that the alloy had been sensitized, which resulted from heating during welding. Electron probe x-ray microanalysis showed the outside surface of the tube did not have the protective chromium oxide scale normally found on Incoloy 800. The inside surface of the tube had a thin chromium oxide protective scale. This evidence supported the conclusions that the deep oxidation greatly decreased the strength of the weld HAZ and cracking followed.","PeriodicalId":231268,"journal":{"name":"ASM Failure Analysis Case Histories: Failure Modes and Mechanisms","volume":"35 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":"127813072","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