为探究不同合金系焊缝金属对热输入的适应性，用Si-Mn，Si-Mn-Ni，Si-Mn-Ti-B三种合金系的焊材分别以24和35 kJ/cm的热输入对420 MPa低合金高强度钢板进行埋弧焊. 经过冲击、拉伸、硬度试验及光学显微镜、扫描电镜分析，对熔敷金属的组织、性能进行研究. 结果表明，随着热输入增加，再热区比例增大，晶粒长大，三种合金系的韧性均下降，其中Si-Mn合金系对大热输入的适应性最差，脆性转变温度由−70 ℃降到−65 ℃；Si-Mn-Ni合金系析出大量呈方向性的贝氏体，恶化韧性;而Si-Mn-Ti-B合金系提供大量高熔点含Ti的形核质点，促进针状铁素体形成，改善韧性.
To explore the adaptability of different alloy of weld metal on the heat input, high strength low alloy steel（HSLA）is welded by submerged arc welding，which uses three alloy systems （Si-Mn, Si-Mn-Ni, Si-Mn-Ti-B）of welding material with heat input 24 and 35 kJ/cm respectively. By Charpy impact，microhardness test，tensile test and analysis of optical microscope, scanning electron microscopy (SEM), the microstructure and properties of the cladding metal are studied. The results show that with the increase of heat input, the reheated zone develops deeper, grain size grows and then the toughness of three kinds of alloy weld metal deteriorates. Si-Mn alloy has the worst adaptability to large heat input, and ductile-brittle transformation temperature decreases from −70 ℃ to −65 ℃. The toughness of Si-Mn-Ni alloy deteriorates because of a large number of directional bainite precipitated on the boundary of ferrite. The Si-Mn-Ti-B alloy weld metal provides a lot of nucleating particles containing Ti, promotes the formation of acicular ferrite to improve toughness.
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