Super304H钢焊接接头的时效组织及其持久性能

Aging Microstructure and Creep Rupture Properties of Super304H Steel Welded Joint

对Super304H钢焊接接头进行了700℃保温不同时间(100,300,500h)的时效处理,研究了其时效组织和冲击性能,并分析了焊接接头在700℃、不同应力下的持久性能。结果表明:700℃时效100h后,Super304H钢焊接接头奥氏体晶界和枝晶界处析出大量的颗粒状、链球状和条状M23C6析出相,焊接接头的冲击韧性显著下降,随着时效时间的延长,M23C6相的析出速率减慢,冲击功基本保持稳定;焊接接头持久试样均在母材处断裂,且断裂前均发生明显的缩颈现象;当加载应力(180MPa)较高时,断口主要呈穿晶断裂特征,而当加载应力(160 MPa)较低时,其断裂特征向沿晶断裂转变。

Super304 Hsteel welded joint was aged at 700 ℃for different times（100,300,500 h）,and the aging microstructure and impact property of the welded joint was investigated.The creep rupture properties of the welded joint at 700℃ under different stresses were analyzed.The results show that after aging at 700℃for 100 h,granular,hammer-like and strip-like M23 C6 phase precipitated from grain boundaries and dendritic grain boundaries of austenite in the Super304 Hsteel welded joint,and impact toughness of the welded joint decreased apparently.With the increase of aging time,precipitating rate of M23 C6 phase slowed down and the impact toughness became stable.The creep rupture sample of welded joint all fractured at the position of base material,and obvious necking occurred before fracture.The fracture mainly showed transgranular characteristic when the loading stress（180 MPa）was relatively high,and changed into intergranular characteristic when the loading stress（160 MPa）was relatively low.