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采用Gleeble-3800热模拟机对深海用X70厚壁管线钢进行热模拟试验,研究在不同焊接线能量下粗晶热影响区的组织转变及性能变化。结果表明:不同焊接线能量下焊接粗晶热影响区组织主要是板条状贝氏体和粒状贝氏体。冷却时间t_(8/5)在12~50s内,适量的粒状贝氏体以不同位向分割板条贝氏体,M-A组元呈块状弥散分布,粗晶区的韧性最好。t_(8/5)<12s时,组织由粗大的板条束贝氏体和条状M-A岛组成;t_(8/5)>50 s时,粒状贝氏体和多边形铁素体增多。这些组织导致冲击韧性降低。
The thermal simulation of X70 heavy wall pipeline steel for deep sea was carried out by using Gleeble-3800 thermal simulator to study the microstructure and properties change of the coarse heat affected zone under different welding line energies. The results show that the microstructures of HAZ in the welding are energy of lath bainite and granular bainite. Cooling time t_ (8/5) In the 12 ~ 50s, the amount of granular bainite segregated in different directions to the lath bainite, M-A component was massive dispersion, the best toughness of the coarse grain region. T_ (8/5) <12s, the organization consists of coarse lath bainite and strip M-A island composition; t_ (8/5)> 50 s, the granular bainite and polygonal ferrite increased. These organizations lead to a decrease in impact toughness.