【摘要】 采用焊接热模拟技术对高铌X80管线钢进行了热模拟试验,研究了在不同焊接热模拟工艺下贝氏体组织的转变及冲击韧性的变化。结果表明:在不同的焊接热循环条件下,焊接粗晶区组织主要是板条贝氏体和粒状贝氏体。冷却时间t8/5为10 s时,适量的粒状贝氏体起到了分割板条贝氏体的作用,且MA岛的数量较少,呈粒状均匀分布于奥氏体内,使得冲击韧性达到最佳。t8/5减小会导致粗大板条束和条状MA岛的产生;t8/5增大,导致大量粒状贝氏体的产生,均会导致韧性的降低。更多还原

【Abstract】 The morphology of bainite and toughness was investigated in CGHAZ of the high Nb X80 pipeline steel after simulated weld thermal cycle.The result shows that the microstructure formed after thermal cycle is mainly lath bainite and granular bainite in CGHAZ.When the cooling time is 10 s,impact toughness is highest for appropriate granular bainite which make the lath bainite finer for the function of partition,and fine martensite-austenite constituent(MA).The toughness will decrease whether the value of cooling time is lower or higher.The reason is that the percent of coarse lath bainite increase and MA constituent is strip for cooling time of less than 10 s,and the percent of granular bainite increase sharply for cooling time more than 10 s.更多还原