Cause analysis of abnormal fracture of 20Mn2A lifting chain
The lifting chain is an indispensable lifting rigging for lifting heavy objects，it has special re⁃quirements for material performance. The hot rolled wire rod is required to have high plasticity, weldabili⁃ty and hardenability when processing cold deformation of braided chain, so as to meet the requirements of machine-shaping of the lifting chain and mechanical properties after heat treatment. The alloy struc⁃tural steel 20Mn2A wire rod has high plasticity during cold deformation，compared with carbon steel with corresponding carbon content, it has higher hardenability and is suitable for the material of lifting chain. This paper studies the failure phenomenon of several lifting chains with insufficient fracture strength , looking for problems the cause of the problem from the raw materials quality and processing technic, based on the test and analysis results of chemical composition, metallographic structure and fracture mor⁃phology of the fracture part of the chain, it is pointed out that the surface decarburization caused by im⁃proper pretreatment, raw material composition change and mechanical damage are the main reasons for the reduction of the mechanical performance of the chain, and the improvement measures are formulated accordingly.
NETL
NSTL
万方数据
