微Ti钢焊接热循环过程中的第二相粒子

采用“Ｓｐｅｅｄ”法电解萃取复型技术,用透射电子显微镜,研究了分别含有Ｔｉ－Ｎ和Ｔｉ－Ｎｂ－Ｎ的两种微合金钢焊接热模拟后,第二相粒子的溶解析出行为及对焊接热循环的响应。系统测定了不同热模拟工艺下第二相粒子的尺寸、数目及分布特征;分析了热模拟工艺参数（峰值温度Ｔｐ,保温时间ｔｐ,冷却时间ｔｍａｘ／８）对析出颗粒尺寸分布特征的影响,探讨了钢中第二相颗粒的长大、溶解行为对高温奥氏体晶粒度的影响以及微量Ｎｂ与Ｔｉ复合添加的作用。结果表明,微量Ｔｉ－Ｎｂ复合合金化对高温奥氏体晶粒的细化经仅用微Ｔｉ合金化的钢更强烈,钢中微细第二相粒子对细化高温奥氏体晶粒具有主要作用。

Second Phases Particles Existing during Weld Thermal Cycle in Microalloying Ti Steel

Behavior of dissolution precipitation and response to simulated weld thermal cycles of fine second Phase particles in two microalloying steels were studied using transmission electron microscope (TEM ) by means of" speed" carbon extraction replicas technique. The sizes, numbers and distribution characteristics were determined as with different simulated weld thermal cycles. Effects of parameters of weld thermal cycle (i. e pulse temperature Tp, holding time at pulse temperature tp and cooling rate from pulse temperature tmax/8 ) on the size and distribution of particles were analysized. An investigation into effects of growth and dissolution behavior of particles on austenite grain sizes at high temperature and action of added element Nb to microalloying Ti steels wes conducted.