煤矿机械用Q690高强钢抗裂性研究

Study on cracking resistance of Q690 high strength steel for mining machinery

对煤矿机械用Q690高强钢,采用其配套焊丝(GHS75M)进行抗裂性试验,并测定了焊丝熔敷金属扩散氢逸出特性,研究了焊缝金属残余扩散氢对试验用钢抗裂性的影响.结果表明:该钢具有一定的冷裂倾向.试验焊材熔敷金属扩散氢含量为1.7 mL/100 g,初期扩散氢逸出速率较大,在焊缝冷却过程中扩散氢可以较快逸出.残余扩散氢含量主要与从峰值温度到100℃温度区间的冷却时间t100有关,单道焊焊缝金属冷速快,t100较小,残余扩散氢较多,而多层多道焊增加了t100,且提高HDr100容许值,残余扩散氢含量很低.该钢采用焊后热处理是保守的工艺.

Cracking resistance test were carried out on the Q690 high strength steel with supporting wire ( GHS75M ) , HD escape characteristics of deposited metal was measured, and the influence of residual diffusible hydrogen on cracking resistance of this steel was analyzed. The results show that the steel has high tendency to hard quenching. Diffusible hydrogen of deposited metal is 1. 7 mL/100 g. At initial stage, the escape rate of HD is high, and HD is escaped quickly. Residual diffusible hydrogen content is mainly related with t100, single-pass welding is cold fast, corresponding, t100 is short, thus, there will be more HDr100. However, t100 is longer with multi-pass welding, in the same time, the allowable value of HDr100 is increased, and HDr100 is lower. Postweld heat treatment for this steel is a conservative process.