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用焊接热模拟方法研究了焊接线能量对12Ni3 MoV钢近缝区组织变化和韧性的影响。结果表明,粒状贝氏体中的M—A组织是近缝区低温韧性急剧恶化的主要原因。粒状贝氏体中以M—A形式存在的残留奥氏体的两种转变——形变诱发转变和变温转变对韧性有不同影响。前者对韧性有利,是含有多量残留奥氏体的粒状贝氏体组织具有较高常温冲击值的原因。后者对韧性有害,是促使含有多量残留奥氏体的粒状贝氏体组织低温脆化的原因。
The effect of welding wire energy on the microstructure and toughness of the near-seam region of 12Ni3Mov steel was studied by means of welding thermal simulation. The results show that the M-A structure in granular bainite is the main reason for the sharp deterioration of the low-temperature toughness near the seam. Two kinds of transformation of retained austenite in the form of M-A in granular bainite - deformation induced transformation and variable temperature transformation have different influences on the toughness. The former is good for toughness and is the reason that the granular bainite containing a large amount of retained austenite has a higher normal-temperature impact value. The latter is detrimental to toughness and is responsible for the low-temperature embrittlement of granular bainite containing large amounts of retained austenite.