热输入对800 MPa级钢接头组织及性能的影响

系统研究了焊接热输入对新一代800MPa级高强度结构钢(RPC钢)焊接接头组织及力学性能的影响。研究结果表明，采用最新研制的超低碳贝氏体焊丝焊接800MPa级RPC钢获得了强韧性匹配良好的焊接接头；焊缝一次柱状品的宽度随热输入的增加而增大，焊缝金属二次组织中基本上消除了先共析铁素体和侧板条铁素体，组成焊缝的基本类型为板条贝氏体、针状铁素体和粒状贝氏体；随着热输入的增大，焊接接头的抗拉强度逐渐降低，而低温冲击韧度则先升高，然后又下降；在热输入为20kJ／cm时焊缝金属低温韧性出现峰值与焊缝获得细小密集的针状铁素体组织有关。

Effect of heat input on structure and mechanical properties of welded joint in a 800 MPa grade RFC steel

The effect of heat input on the structure and mechanical properties of the welded joint in a new generation SOOMPa grade structural steel (RPC steel)has heen investigated. The results show that using the ultra low carbon hainitic welding wire to weld the SOOMPa grade RPC steel, the welded joints with the combination of high strength and good toughness rould be achieved. With the increase of the heat input, the width of the dendrite increased. The primary ferrite and sideplate ferrite are almost removed completely in the secondary structure of the weld metal, and the lath bainite,acicular ferrite (AF) and granular bainite are the main mi-costructure components. When the heat input is increased, the tensile strength decreases gradually, but the low temperature impact toughness initially increases and then decreases. The peak of low temperature impact toughness at heat input of 20kJ/o,m is related to the fine and dense of AF obtained in the weld metal.