机械振动对Q690钢焊接接头组织与性能的影响

Effect of Mechanical Vibration on Microstructure and Properties of Welded Joint of Q690 Steel

在Q690钢熔化极活性气体保护焊过程中施加机械振动,研究了机械振幅和振动频率对Q690钢焊接接头力学性能的影响,并对断口形貌进行了观察。结果表明,固定振动频率,焊接接头试样的抗拉强度、断后伸长率、断面收缩率和冲击功都随着振动幅度的增加先增加而后减小,在振幅为0.04 mm时取得最大值,无振动和施加机械振动的焊接接头的拉伸断裂位置都位于焊缝处;振幅为0.02～0.06 mm时,冲击断口呈现韧性断裂特征,而振幅0.08 mm时冲击断口为脆性断口。固定振幅,焊接接头试样的抗拉强度、断后伸长率、断面收缩率和冲击功都随着振动频率增加而降低,振动频率为25Hz时的强塑性和冲击功高于无振动焊接接头,而振动频率为35、45和55 Hz时的强塑性和冲击功都小于无振动焊接接头;振动频率为25～45 Hz时的冲击断口为韧性断口,而55 Hz时的断口呈脆性断裂特征。

Mechanical vibration was applied in the process of metal active gas protection welding of Q690 steel.The effect of mechanical amplitude and vibration frequency on the mechanical properties of welded joint of Q690 steel was studied,and the fracture morphology was observed.The results show that when the vibration frequency is canstant,the tensile strength,the elongation,the percentage reduction of area and the impact energy of the welded joint specimens increase first and then decrease with the increase of the vibration amplitude,and the maximum value is obtained when the amplitude is 0.04 mm.The tensile fracture positions of the welded joint with and without mechanical vibration are all located in the weld seam.When the amplitude is 0.02-0.06 mm,the impact fracture is characterized by ductile fracture,while the impact fracture is brittle fracture when the amplitude is 0.08 mm.When the amplitude is constant,the tensile strength,the elongation,the percentage reduction of area and the impact energy of the welded joint all decrease with the increase of the vibration frequency.The strength,plasticity and impact energy of the joint under the vibration frequency of 25 Hz are higher than those of the welded joint without vibration,while the strength,plasticity and impact energy of the joint under the vibration frequency of 35 Hz,45 Hz and 55 Hz are less than those of the welded joint without vibration.The fracture of the welded joint is ductile fracture when the vibration frequency is 25-45 Hz,while the fracture under the vibration frequency of 55 Hz is brittle fracture.