履带限位块开裂分析

Cracking Analysis of Stop Blocks in Caterpillar Bands

车辆履带在拆卸维护过程中发现部分限位块有裂纹,对装配完一段时间未出厂的履带进行检查,发现也有部分限位块存在裂纹。为了确定限位块的开裂性质和原因,开展宏微观观察、能谱成分分析、金相组织检查、硬度测试、H含量测定以及排查对比试验。结果表明:限位块开裂性质为氢致延迟脆性开裂;限位块材料硬度接近设计上限并且脆性较大,本身具有较高的氢脆敏感性;渗锌过程中引入H导致限位块表层H含量较高,是限位块发生氢脆开裂的主要原因。调整渗锌工艺,防止渗锌过程中引入H,可有效预防限位块氢致裂纹的产生。

Part of the stop blocks in the caterpillar band of a vehicle were found to have cracks during the process of maintenance,and some stop blocks were also found to have cracks after assembling for a while but before service.In order to determine the failure mode and cause of the stop blocks,macro and micro observation,energy dispersive X-ray spectroscopy(EDS)analysis,microstructure examination,hardness testing,hydrogen content testing and comparison experiments were carried out.The results show that the cracking of the stop blocks is intergranular cracking due to hydrogen embrittlement.The hardness of the stop blocks material is close to the design upper limit and the material itself has higher brittleness,leading to a high hydrogen embrittlement sensitivity of the material.The cracking of the stop blocks was mainly caused by the higher hydrogen content of the surface layer,which was due to the ingress of hydrogen during the zincizing process.It has been proved that preventing the ingress of hydrogen during the zincizing process can effectively prevent the hydrogen-induced cracking of the stop blocks.