【名词&注释】
热应力(thermal stress)、奥氏体不锈钢(austenitic stainless steel)、线膨胀系数(linear expansion coefficient)、珠光体耐热钢(pearlitic heat resistant steel)
[填空题]奥氏体不锈钢与珠光体耐热钢(pearlitic heat resistant steel)焊接时的焊接接头中会产生较大的热应力,其原因是().