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通过不同冷却速度条件下的热模拟实验和显微硬度测试对高强度桥梁钢进行了焊接热影响区组织相变的研究。实验结果表明:Q460q当冷速较慢时,热影响区奥氏体内部形成大量的针状铁素体、少量珠光体、粒状铁素体和少量粒状贝氏体的混合组织;随着冷却速度加快,铁素体的量减少,粒状贝氏体的量不断增多,显微硬度值升高;当冷却速度进一步加快,组织中板条贝氏体量增多,开始发生部分马氏体相变,显微硬度急剧升高。
The phase transition in the HAZ of high strength bridge steel was studied by thermal simulation and microhardness test under different cooling rates. The experimental results show that: Q460q when the cooling rate is slow, a large amount of acicular ferrite, a small amount of pearlite, granular ferrite and a small amount of granular bainite mixed structure formed within the heat-affected zone austenite; with the cooling rate Accelerate the reduction of the amount of ferrite, the amount of granular bainite increasing, the microhardness value increased; when the cooling rate is further accelerated, the organization increased the amount of lath bainite, martensitic transformation began to occur, Microhardness increased dramatically.