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开发了含碳量极低,含Mn、Ni的金属焊线。使用该金属焊线在Ar-2%O_2保护气氛中制备得到不同Mn、Ni含量的低碳焊接金属,并测试其组织和力学性能。结果表明:随着Ni含量的增大,无论低Mn还是高Mn的焊层柱晶区微观组织均出现板条马氏体相,晶界铁素体含量降低。低Mn和低Ni高Mn的焊层再加热区微观组织均以铁素体为主;随着Ni含量的增加,高Mn焊层再加热区的柱状晶含量增大。焊材金属硬度与Mn和Ni含量的增加呈线性关系。Ni影响焊层的冲击性能,其变化取决于Mn含量。Mn含量低时,Ni增加硬度但不会降低冲击韧性;Mn含量高时,较大含量的Ni严重地恶化冲击韧性,引起沿晶断裂。为了获得较高的硬度与冲击韧性,焊材金属Mn与Ni的最佳含量分别为0.5%~1%和4%~5%。
Developed with a low carbon content, including Mn, Ni metal wire. Low-carbon weld metal with different content of Mn and Ni was prepared by using this metal wire in Ar-2% O 2 atmosphere and its microstructure and mechanical properties were tested. The results show that with the increase of Ni content, the lath martensite phase appears in the microstructure of the columnar grain boundaries and the grain boundary ferrite content decreases with the increase of Ni content. The microstructure of the reheating zone with low Mn and low Ni and high Mn are mainly ferrite. With the increase of Ni content, the columnar crystal content in reheating zone of high Mn welding zone increases. The hardness of the weld metal is linear with the increase of Mn and Ni content. Ni affects the impact properties of the solder layer, the change depends on the Mn content. When the content of Mn is low, Ni increases the hardness but does not decrease the impact toughness. When the content of Mn is high, the larger content of Ni seriously deteriorates the impact toughness and causes the intergranular fracture. In order to obtain high hardness and impact toughness, the optimal content of Mn and Ni in the weld metal is 0.5% ~ 1% and 4% ~ 5%, respectively.