X-60微合金钢的焊接接头韧性

利用光学显微镜、金属薄膜TEM分析、电子显微分析、CHARPY冲击试验和COD试验,研究了X-60钢的CG-HAZ组织中第二相粒子行为以及焊接接头韧性.结果表明,细小弥散的第二相粒子能有效地阻碍焊接热影响区粗晶区的原奥氏体晶粒长大,改善该区域的韧性.不同的800～500℃冷却时间,第二相粒子在热循环过程中溶解、粗化以及再析出行为不同,因而其阻碍奥氏体晶粒长大的能力也不同.t8/5由10s增大到70s时,CG-HAZ显微组织由上贝氏体+粒状贝氏体转变为粒状贝氏体,且奥氏体晶粒尺寸稍有长大,因此其韧性略有下降.

Study on Welding Joint Toughness of X-60 Steel

Charpy impact test and COD test were carried on the specimens subjected to simulated weld thermal cycle and the specimens made from weld joint. The optical microscope, TEM and SEM analysis were used to investigate the behaviors of second phase particles and the effects of microstructure on toughness separately. The results show that the dispersed second phase particles can effectively retard the growth of austenite grain in the CGHAZ, and improve the toughness. When t 8/5 is different, the behaviors of the particles are also different in dissolving, coarsening and re precipitating. The ability of retarding the growth of austenite grain will be affected. When t 8/5 increases from 10 s to 70 s, the microstructure of CGHAZ will transform from upper bainite and granular bainite to granular bainite and the size of austenite grain will grow a little, thus the toughness of materials decreases slightly.