SWRM6盘条拉拔断裂原因分析

Fracture reason analysis of drawing SWRM6 wire coil

某线材厂SWRM6的热轧盘条在用户使用拉拔后发生了断裂。通过取样对该盘条进行了断口宏观形貌、金相微观组织、缺陷及电子探针能谱方面的分析,表明断裂盘条的试样边部均存在裂纹,裂纹处有夹渣,夹渣碳质量分数远远高于基体碳质量分数。由于夹渣的存在,一方面因为其塑性较钢材低,在轧制和拉拔时易形成开裂,另一方面由于其富碳层使基体表面增碳,形成索氏体和网状碳化物等异常组织,加速了盘条拉拔时的断裂。

Fracture of the SWRM6 wire coil occurred after the customer drawing .The investigations of the test of macroscopic observation ,metallographic microstructure analysis and EMPA analysis showed that there were cracks existed at the margin of the sample and there were slags where the carbon content was higher than the basal body lied at the side of the cracks .Because of the existence of slags ,on one hand the low plasticity led to the cracking during rolling and drawing ,on the other hand ,the formation of abnormal tissue martensite and carbide network due to the carburizing from rich carbon layer to the substrate surface accelerated the fracture during drawing .