Microstructure And Mechanical Properties Of Weld Joint Of BWELDY960Q And 20CrMnTi

For engineering components, most people want to use high-strength steel to reduce material consumption, but there is less research about the welding of high-strength steel. In order to develop the application of high-strength steel preferablely, it has practical sense to investigate the microstructure and mechanical properties of weld joint for this kind of steel. Based on the low-carbon high-strength steel BWELDY960Q and forging state 20CrMnTi produced by Shanghai Baosteel, with the SLD-80 welding wire and TUnion GM 100 welding wire, and using the method of CO2 gas shielded arc welding, the influences of wire and heat treatment on the microstructure and mechanical properties of welded joint were studied.The results showed that, for the welded joints of the low-carbon high-strength steel(BWELDY960Q), there is a great difference between the two wire welding results, ie. SLD-80 welding wire and TUnion GM 100 welding wire. The materials which after welding by SLD-80 welding wire have good mechanical properties; Quenching and tempering treatment(900℃×2h×oil cooling+650℃×1h×air cooling) can improve the synthesized mechanical properties of the steel effectively, after heat treatment, strength and hardness of the steel are lower than before, but the ductility and toughness are improved significantly. In contrast, the materials which welded by SLD-80 welding wire has good mechanical properties; For SLD-80 welding wire, annealing treatment can improve the mechanical properties significantly for the welded joints of BWELDY960Q steel, in addition, after annealing at 550℃, the weldment has the best mechanical properties; For the 20CrMnTi and BWLEDY960Q steel which welded with the two welding wire, and then heat treatment(880℃×2h×oil cooling+300℃×1.5h×air cooling), the microstructure and mechanical properties of the weld joint which welded by using SLD-80 welding wire and TUnion GM 100 welding wire are very similar. It reveals that, the two welding wire are available for the welding of 20CrMnTi and BWLEDY960Q steel; For SLD-80 welding wire, the microstructure and mechanical properties of the steel gained which welded after heat treatment is superior to the steel gained which heat treatment before welding, in the condition of losing little ductility and toughness, strength and hardness of the steel are improved significantly. In contrast with tempering at 300℃, the treatment(880℃×2h×oil cooling+550℃×1.5h×air cooling) after welding which the ductility and toughness are improved significantly when the strength and hardness loss a little. It has good mechanical properties when tempering at 500℃.