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The effect of different peak temperature(T_P) and cooling time(t_(8/5)) on microstructure,hardness,impact toughness and fracture morphology in the heat-affected zone(HAZ) of HQ130 steel was studied by using weld thermo-simulation test.Experimental results indicate that the impact toughness and hardness decrease with the decrease of T_P or increase of t_(8/5) under the condition of a single thermal cycle.There is a brittle zone in the vicinity of T_P = 800 ℃,where the impact toughness is considerably low.There is a softened zone in the vicinity of T_P = 700℃,where the hardness decreases but the toughness increases.In the practical application of multi-layer and multipass welding,the welding heat input should be strictly limited(t_(8/5)≤20s) so as to reduce the softness and brittleness in the HAZ of HQ130 steel.
The effect of different peak temperature (T_P) and cooling time (t_ (8/5)) on microstructure, hardness, impact toughness and fracture morphology in the heat-affected zone (HAZ) of HQ130 steel was studied by using weld thermo-simulation test. Experimental results indicate that the impact toughness and hardness decrease with the decrease of T_P or increase of t_ (8/5) under the condition of a single thermal cycle. Here is a brittle zone in the vicinity of T_P = 800 ° C., where the impact toughness is considerably low. Here is a softened zone in the vicinity of T_P = 700 ° C, where the hardness decreases but the toughness increases. In the practical application of multi-layer and multipass welding, the welding heat input should be strictly limited (t_ (8/5) ≤20s) so as to reduce the softness and brittleness in the HAZ of HQ130 steel.