{"title":"Fracture of Cast Steel Equalizer Beams","authors":"","doi":"10.31399/asm.fach.auto.c0089572","DOIUrl":null,"url":null,"abstract":"\n 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":0.0000,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"ASM Failure Analysis Case Histories: Automobiles and Trucks","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.31399/asm.fach.auto.c0089572","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
Abstract
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.
两根砂铸低合金钢平衡梁(ASTM A 148,等级105-85)设计用于将载荷分配到高速公路卡车的车轴上,在未报告使用时间后断裂。卡车的正常使用寿命约为805,000公里(500,000英里)。调查(目视检查,化学分析,拉伸测试,未蚀刻65倍和1%数字蚀刻65倍放大)支持的结论是,钢太软,不适合应用-可能是由于热处理不当。平衡梁断裂的原因是铸件热处理前形成的机械裂纹的扩大。建议包括以下工艺上的变化:在铸造厂中更好地浇注和冒口,以实现更坚固的铸件;更好的出砂练习,避免机械损伤;更好的检测缺陷;并进行正火和回火以达到更好的机械性能。