【摘要】 采用萃取复型技术,对经受焊接热循环不同阶段的试样进行研究,分析了TiN粒子在焊接热循环不同阶段的溶解、粗化及再析出行为。结果表明,小尺寸粒子的溶解与大尺寸粒于的粗化并不是同步进行的,后者滞后于前者;在焊接热循环的低温加热阶段(室温至1200℃以下),粒子的溶解以粒子的尺寸减小为主要特征,单位面积内粒子的数量变化不大;在焊接热循环的高温加热阶段(1200～1350℃),粒子的溶解导致大量小尺寸粒子消失,粒子平均尺寸显著增大;在焊接热循环冷却过程的高温阶段(1350～1300℃),粒子仍继续溶解;在冷却过程的低温阶段(1300℃以下),固溶状态的Ti与N结合并沉淀到残留的TiN粒子上,使粒子粗化。在焊接热循环过程中,Ti微合金钢原始奥氏体晶粒粗化主要发生在冷却阶段。更多还原

【Abstract】 Carbon extraction replica analysis is employed to measure number and size distribution of particles in Ti micro-alloyed steel specimens which are subjected to different welding thermal cycle so as to study the dissolution, coarsening and precipitation of TiN particle in Ti microalloyed steel during different stage of welding thermal cycle. The results showed that the coarsening and re-precipitation lag behind dissolution seriously, and the coarsening mechanisms in different stage of the welding thermal cycle is different. At the low temperature stage (lower than 1 200 ℃) of heating leg of welding thermal cycle, the dissolution is characterized by shrinkage of particles, the number of particles did not decrease noticeably, indicating that particle coarsening is very weak. At the high temperature stage (1 200 - 1 350℃) of heating leg of welding thermal cycle, the mean particle size increase strikingly through disappearance of a large number of small particles. In the cooling stage from 1 300 ℃ to 1 350℃, particle coarsening and dissolution still occurred due to lag effect. In the cooling stage from 1 300℃to room temperature, solute Ti and N are combined to reprecipatated onto the survived particles, thus the mean size increase remarkably. The austenite grains coarsening mainly occurred in the cooling stage of the welding thermal cycle.更多还原