18-8型奥氏体不锈钢锅炉管服役特性研究(四)

STUDY ON SERVICING PROPERTIES OF BOILER TUBES MADE FROM 18-8 TYPE AUSTENITIC STAINLESS STEEL(4)

对18-8型奥氏体不锈钢锅炉管在服役过程中力学性能的变化规律及其蠕变断裂特征进行了研究。结果表明:18-8型奥氏体不锈钢锅炉管在服役过程中室温抗拉强度、硬度值随服役时间的延长总体上呈升高趋势,而室温屈服强度变化不明显;在寿命尾期,当组织中出现明显蠕变损伤时,强度和硬度值会急剧下降;断后伸长率、断面收缩率及冲击吸收能量随服役时间的延长总体上呈明显的下降趋势;随蠕变断裂时间的延长,奥氏体不锈钢依次呈现出由延性穿晶断裂到沿晶断裂的3种不同蠕变断裂模式。

The changing regularity of mechanical behavior and the creep rupture properties of boiler tubes made from 18- 8 type austenitic stainless steel in servicing process have been studied,results show that the tensile strength and the hardness value under room temperature of said boiler tubes in servicing process in general have a rising tendency along with the lengthening of servicing time, but the variation of yield strength isn＇t remarkable; during the end period of servicing life, the strength and hardness value may suddenly reduce, the specific elongation after rupture, the shrinkage rate of cross- section,and the energy absorbed by impact,in general,have a decreasing tendency along with lengthe- ning of the servicing life,along with lengthening of creep rupture life,the austenitic stainless steel ap- pears sequencially three kinds of creep rupture modes from the grain -penetrating rupture to the along grain rupture.