对T91这种低合金Cr-Mo钢的PWHT 后的硬度规定, 可参考AWS D10.8.(Cr-Mo piping systems are usually selected for corrosion resistance, high-temperature creep strength, or both.Corrosion resistance is often associated with maximum hardness)另还可参考其他:材料焊缝硬度的控制要求,在硫环境中,NACE MR0715,NACE MR0103中有非常具体的规定.母材、焊缝和热影响区的硬度在决定碳钢和低合金钢抗SSC(sulfide stress cracking) 性能方面起着重要作用,控制硬度是一种获得抗SSC 性能的可接受方法.还可以参考看下NACE SP0472(for Carbon Steel, thoughT91 is low alloy steel).
简单的说,硬度增加,抗腐蚀&抗裂纹性能减弱. |