经调质和渗氮处理的4Cr13钢送丝辊在使用中生锈。化学成分分析表明，送丝辊含铬量偏低，为10．60％。金相检验表明，送丝辊渗氮层深度为0．12 mm，表面硬度约为1000 HV0．2，但有较严重的疏松和黑色组织，是导致送丝辊生锈的根本原因。%A kind of wire-feeding roller,made of 4Cr13 steel and subjected to hardening and high tempering followed by nitriding,was found to rust in service.From chemical composition analysis it was found that chromium content of the rusty wire-feeding roller is lower-than-normal value of 10.60%.From metallographic examination it was shown that the nitrided case exhibited as deep as 0.12 mm and as high hardness as 1 000 HV0.2,but more significant porosity and dark structure existed in it,these two defects being fundamental reason why the wire-feeding roller rusts.
展开▼
