材料期刊网

采用热模拟技术研究高铌X80管线钢的在不同的焊接热循环条件下的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。t8/5为10s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，使的冲击韧性达到最佳。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。

The morphology of bainite and toughness was investigated in CGHAZ of the high Nb X80 pipeline steel after simulated weld thermal cycle. The result show that the microstructure formed after thermal cycle was mainly lath bainite and granular bainite in CGHAZ .When the cooling time is 10 seconds, 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 10s and the percent of granular bainite increase sharply for cooling time more than 10s.