Effect of Weld Heat Input on Weld Joint of B610CF Steel

B610CF steel is a low carbon bainite steel manufactured using alloyage and thermo-mechanical controlled processes(TMCP) technology. The effect of weld heat input on weld joint of B610CF steel using shielded metal arc welding method and mixed active gas arc welding method was investigated by metallographic experiment and mechanical property experiment. Results of metallographic experiment and mechanical property experiment show that when using the same welding method, in weld metal with the increasing of weld heat input the quantity of bainite is decreased and crystalline grain size is become larger, and the impact toughness decreases; but in heat affected zone, there is no distinct difference in microstructure and impact toughness. And there is no distinct difference in tensile strength and plasticity in weld joint. It can be concluded that in order to improve the quality of B610CF steel weld joint, larger weld heat input should be avoided.