线能量对插销临界应力的影响

本文用Ar+20％CO_2气体保护焊方法对15MnVN钢进行插销试验,试验结果表明,焊接线能量在15～40 kJ/cm范围内,插销试验的临界断裂应力高于15MnVN钢的屈服强度;也高于用J507焊条及J557MoV焊条电弧焊15MnVN钢插销试验的临界断裂应力。观察金相试样得知,15MnVN钢焊接热影响区组对焊接线能量比较敏感,脆硬马氏体及粗大铁素体的产生都会降低插销试样的临界断裂应力。为使15MnVN钢焊接热影响区获得最佳组织和最好的抗裂性能,焊接线能量应选择20～30 kJ/cm。

EFFECT OF HEAT IMPUT ON CRITICAL IMPLANT STRESS

Implant tests were conducted on 15MnVN steel using Ar+20% CO2 gas shielded welding process. The test results shown that the critical fiacture stresses are all above the yield stress of ISMnVN steel in the welding heat input range of 15-40kJ/cm,and they are also higher than those of using J507 and J557MoV welding electrodes. Metallographic results show that the microstructure of heat affected zone in 15MnVN steel is very sensitive to welding heat input. The martensite and coarse ferrite in heat affected zone of 15MnVN steel reduce the critical fracture stress of implant tests. A welding heat input of 20-30 kJ/cm should be chosen so as to enable the heat affected zone of 15MnVN steel to have optimum microstructure and resistance to cracking.