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使用Gleeble3800试验机模拟二次热循环过程,对V-N和Nb-V微合金钢的临界再热粗晶热影响区(intercritically reheated coarse grain heat-affected zone,ICCG HAZ)的组织和冲击性能进行了对比。结果表明:二次热循环后,V-N钢临界再热粗晶热影响区中有铁素体存在,阻止了裂纹的扩展,有利于焊接热影响区冲击性能的提高;Nb-V钢临界再热粗晶热影响区多为贝氏体组织,无法阻止裂纹扩展,因此冲击性能很差。二次热循环后,V-N钢M-A组元面积分数为0.76%,平均尺寸1.1μm,多分布于晶内;而Nb-V微合金钢M-A组元达8.6%,平均大小为2.4μm,且晶界上呈环状分布。M-A组元极易与基体组织脱离,从而造成裂纹的启裂与扩展,致使冲击性能极差。
The structure and impact properties of intercritically reheated coarse grain heat-affected zone (ICCG HAZ) of VN and Nb-V microalloyed steels were compared using a Gleeble 3800 simulator for secondary thermal cycling . The results show that ferrite exists in the heat affected zone of VN reheating coarse grain after secondary thermal cycle, which can prevent the crack growth and improve the impact performance of Nb heat treatment zone. Critical reheating Coarse grain heat affected zone mostly bainite, can not prevent crack growth, so the impact performance is poor. After the second thermal cycle, VN steel MA component area fraction of 0.76%, an average size of 1.1μm, distributed in the crystal; and Nb-V microalloyed steel MA group element of 8.6%, the average size of 2.4μm, and the crystal The world was ring-shaped distribution. M-A component easily detached from the matrix, resulting in crack initiation and expansion, resulting in very poor impact performance.