微量Nb对微Ti钢焊接HAZ奥氏体晶粒长大的影响

Effect of Nb Addition on Austenite Grain Growthing in HAZ of Minor Ti Bearing Steels

研究０．０２％Ｎｂ对低碳Ｔｉ－Ｎ钢高温奥氏体晶粒长大的影响。对含Ｎｂ量相同、含Ｔｉ量不同的一组试样进行了焊接热模拟试验及高温奥氏体晶粒度测试；用透射电镜分析了钢中第二相颗粒（Ｔｉ，Ｎｂ）Ｎ的形貌和尺寸分布特点；研究了奥氏体晶粒度随试样成分、峰值温度、保温时间以及第二相粒子的尺寸分布而变化的规律；探讨了添加的Ｎｂ在焊接过程中的作用机理。

Effect of 0.02% Nb addition on austenite grain growthing at high temperature in HAZ of low carbon Ti-N bearing steels was studied. The simulated welding thermal cycle was applied to a set of steels with the same Nb content and the different Ti content. The austenite grain size at high temperature was also measured. The characteristics of morphology and the distribution of second phase particles in steels have been observed by TEM. The rule that austenite grain size varies with composition of steels, peak temperatures and holding times was investigated. The acting mechanism of added Nb during welding was discussed.