热输入对9Ni钢熔敷金属组织与性能的影响
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摘要
采用三种热输入对9Ni钢进行埋弧焊接,通过金相显微镜及扫描电镜观察热输入对焊缝显微组织影响,比较了不同热输入下枝晶中心处Cr、Mo元素含量及熔敷金属的拉伸性能、低温韧性,分析了冲击断口形貌。结果表明,焊缝组织均为奥氏体,并伴有一定析出物;随着热输入的提高,焊缝组织晶粒粗化,枝晶间距变宽,但析出物含量减少,枝晶中心Cr元素含量减少,Mo元素含量增加。热输入为15 kJ/cm时,抗拉强度为724 MPa,低温(-196℃)平均冲击吸收能量为68J,断口韧窝尺寸大而深。
9 Ni steel was welded by submerged arc welding(SAW)under three heat inputs. The effects of heat input on microstructure of the deposited metal were investigated by means of OM and SEM, the Cr, Mo contents at the center of dendrites, tensile properties and low temperature toughness of the deposited metals under different heat inputs were compared and the impact fracture morphology was analyzed. The results show that the microstructure of the deposited metal consists of austenite and precipitates. With the increase of heat input, the grain of the welds is coarse and the dendrite spacing is widened,but the precipitates content decreases, the content of Cr in the center of the dendrites decreases, the Mo content increases.When the heat input is 15 kJ/cm, the tensile strength is 724 MPa, the average impact absorption energy at low temperature of-196 ℃ is 68 J, and the size of fracture dimples is big and deep.
9 Ni steel was welded by submerged arc welding(SAW)under three heat inputs. The effects of heat input on microstructure of the deposited metal were investigated by means of OM and SEM, the Cr, Mo contents at the center of dendrites, tensile properties and low temperature toughness of the deposited metals under different heat inputs were compared and the impact fracture morphology was analyzed. The results show that the microstructure of the deposited metal consists of austenite and precipitates. With the increase of heat input, the grain of the welds is coarse and the dendrite spacing is widened,but the precipitates content decreases, the content of Cr in the center of the dendrites decreases, the Mo content increases.When the heat input is 15 kJ/cm, the tensile strength is 724 MPa, the average impact absorption energy at low temperature of-196 ℃ is 68 J, and the size of fracture dimples is big and deep.
引文
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[4]王兆强.置换原子对镁合金形变孪晶钉扎作用的研究[D].西安:西安工业大学,2015.
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