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使用Gleeble3800热模拟试验机对F460钢进行单道次焊接热模拟,得到四种不同热输入下的热模拟试样,并对其进行低温拉伸试验,通过SEM观察粗晶热影响区(CGHAZ)的显微组织、微观断口形貌,分析了CGHAZ的拉伸性能随热输入的变化规律。结果表明:随着热输入的增加,原始奥氏体晶粒与贝氏体团(即有效晶粒)逐渐粗化,相变产物由细密的板条马氏体转变为板条贝氏体与粒状贝氏体的混合组织,其中粒状贝氏体随着热输入的进一步增加而逐渐增加;随着热输入的增加,拉伸屈服强度、抗拉强度以及断面收缩率在20、-95及-196℃试验温度下均逐渐降低;根据拉伸断口微观观察结果表明,起裂源处的解理面尺寸逐渐增大。
Single-pass welding thermal simulation of F460 steel was carried out by using Gleeble3800 thermal simulation test machine to obtain four kinds of thermal simulation samples under different heat input, and the low temperature tensile test was carried out. The CGHAZ was observed by SEM, The microstructure and microstructure of the fracture surface were analyzed. The variation of tensile properties of CGHAZ with heat input was analyzed. The results show that as the heat input increases, the original austenite grains and bainite (ie, the effective grains) gradually coarsen, and the phase transformation products are transformed from fine lath martensite to lath bainite and Granular bainite, in which the granular bainite increases with the further increase of heat input; with the increase of heat input, the tensile yield strength, tensile strength and reduction of area at 20, -95 and - 196 ℃. The microscopic observation results of tensile fracture show that the size of cleavage plane at crack initiation source gradually increases.