23MnV钢矿用链条断裂原因分析

ANALYSIS FOR WELDING BROKEN REASON OF 23MnV CHAIN STEEL USED FOR MINE

23MnV钢矿用链条在焊后预拉试验中断裂。对断裂件的宏观断口、化学成分、显微组织进行了检验并结合焊接工艺进行了分析。结果表明 ,链条烧损是发生预拉早期断裂的直接原因 ,而组织中局部出现的大量粒状贝氏体是链节预拉断裂的内在因素。采用焊前预热和控制焊后冷却速度以及控制碳含量在 0 .2 5 %以下 ,可有效地避免粒状贝氏体的产生 。

MnV chain used for mine break in postwelding pre tensile testing. The fracture face, chemical composition and micro structure of the broken piece were examined, and the welding technique was also analyzed. The results show that the burning loss is the direct reason of the early stage fracture in pre tensile testing. A large number of particulate bainite existing in the partial structure is the internal factor of the broken chain. To take measures of the pre heat before welding and to control the cooling speed after welding can effectively prevent the appearance of the particulate bainite, control the carbon content below 0.25% and reduce the occurrence of the post welding pre tensile fracture.