【摘要】 采用有限元方法对马氏体耐热钢(P91)焊接接头在温度为600℃、应力为80MPa下的最大主应力、von Mises等效应力、等效蠕变应变和应力三轴度进行了数值模拟.结果表明,在接头上下坡口交界处细晶热影响区(FGHAZ)两侧的最大主应力和von Mises等效应力很高,蠕变变形主要集中在FGHAZ,等效蠕变应变的最大值位于FGHAZ的底部.受焊缝和母材的强烈拘束,上下坡口交界处FGHAZ内应力三轴度最大,容易形成蠕变裂纹,导致接头蠕变开裂.数值模拟结果与试验获得的IV型裂纹产生、扩展结果一致.因此采用应力三轴度表征IV型裂纹开裂比较合理.更多还原

【Abstract】 The maximum principal stress,von Mises equivalent stress and equivalent creep strain of the welded joint of martensitic heat-resistant steel(P91) was simulated by FEM under the condition of 600 ℃ and 80 MPa.The results show that the maximum principal stress and von Mises equivalent stress are high on the curved points of two sides of groove faces near the fine grain HAZ.The creep strain mainly concentrates in the fine grain HAZ,the maximum creep strain locates in the bottom of fine grain HAZ of the specimen.The stress triaxiality is maximum in the fine grain HAZ and creep cracking occurs because of the intensive constrain of the base metal and weld.The simulation results are in well agreement with the experimental results of crack initiation site and propagation path by using the stress triaxiality as the mechanically controlling parameter of the martensitic heat-resistant steel weld.Therefore,it is reasonable for the stress triaxiality to be used for analyzing the initiation and propagation of type IV cracking in the fine grain HAZ.更多还原