混凝土泵车臂架腐蚀疲劳失效分析  

Analysis of Corrosion Fatigue⁃Induced Failure in Concrete Pump Truck Booms

作　　者：赵骏 任红娃 吴立惠 ZHAO Jun;REN Hongwa;WU Lihui(Chengdu Metallurgical Experimental Plant Co.,Ltd.,Chengdu 611300,China)

机构地区：[1]成都冶金实验厂有限公司,四川成都611300

出　　处：《材料保护》2025年第2期162-167,共6页Materials Protection

摘　　要：某型混凝土泵车作业过程中,第1级臂架(由20MnTiB钢板制造)的上表面出现折断,造成了巨大的经济损失。为了厘清断裂的原因,对现场截取的断裂臂架进行了断口形貌、成分、力学、金相、扫描电镜等理化检验,检验结果表明,断裂起源于臂架内壁上的点腐蚀坑位置,随后在腐蚀介质和循环应力作用下进行了腐蚀疲劳裂纹扩展,主断裂源金相组织有近似于焊接接头的组织。综合检验结果分析确认:臂架断裂的一级失效模式为腐蚀疲劳断裂;二级失效模式为臂架钢板内壁的点腐蚀坑在富含混凝土成分的水蒸气和臂架承受的周期性弯曲作用下导致的腐蚀疲劳断裂;三级失效模式为焊工在焊接臂架箱体时在钢板上进行了引弧操作,损伤了钢板表面,造成了类似焊接接头的分层组织,最早起裂的点腐蚀坑位于损伤钢板表面粗大的马氏体层上。During the operation of a certain type of concrete pump truck,the upper surface of the first⁃level boom(made from 20MnTiB steel plate)fractures,resulting in significant economic losses.To determine the cause of the fracture,physical and chemical tests including fracture surface morphology,composition,mechanical properties,metallography,and scanning electron microscopy were conducted on the fractured boom collected from the site.The test results showed that the fracture originated from a localized pitting corrosion on the inner surface of the boom,which then propagated under the influence of corrosive media and cyclic stress,leading to corrosion fatigue crack growth.The metallo⁃graphic structure of the main fracture source was similar to that of the welded joint.Comprehensive analysis of the test results confirmed that the primary failure mode of the boom fracture was corrosion fatigue failure;the secondary failure mode was the corrosion fatigue fracture caused by the pitting corrosion pits on the inner wall of the boom steel plate under the action of water vapor that was rich in concrete components and the periodic bending endured by the boom;the tertiary failure mode was attributed to the welder’s arc⁃striking operation on the steel plate during the welding of the boom box,which damaged the steel plate surface,leading to a layered structure similar to that of a weld joint.The earliest pitting corrosion pit was located on the coarse martensite layer on the surface of the damaged steel plate.

关 键 词：混凝土泵车 20MnTiB 臂架 点腐蚀 腐蚀疲劳 引弧 

分 类 号：TG174[金属学及工艺—金属表面处理]