Study On Microstructure And Mechanical Properties Of Q235 Steel And T2 Copper Diffusion Welded Joints

The welding of dissimilar metals can not only reduce cost,but also takes advantage of two kinds of materials in one structure.It has extensive application in the field of modern industry.And diffusion welding technology provides important technical guarantee for the welding of dissimilar metals.This paper mainly studies the composition,microstructure and mechanical properties of the Q235/T2 diffusion welding joint.The conclusions are as follow:(1)Under the circumstance of pressure:15-20MPa,temperature:850-950?,welding time:30 minutes,vacuum degree:2-5×10-1 Pa,vacuum diffusion welding between T2 brass and Q235 Steel is realized successfully.(2)Ensile experiment results show that the fracture occurs at the side of the parent metal T2,and is away from the welded joint.The specimen has a tensile strength of 188.82 MPa and an elongation of 34.22%.The impact experiment results show that the interface between the impact energy of 107.2 J,more than the parent metal T2 impact energy,the parent metal T2 impact energy is 95.3 J.The bending experiment results show that no crack is found at inside and outside of the joint interface.The torsion experiment results show that the fracture occurs at the side of the parent metal T2 and is away from the welding joint.The average value of the maximum torque is 45.23 N·m,the final angle of the sample is the average of 2740.97°.(3)High frequency fatigue test results show that the fracture occurs at the side of the parent metal T2,and is away from the welded joint.The fatigue of specimen strength,under the survival condition of 50%and 95%,are 63.3 MPa and 57.4 MPa respectively.(4)The composite analysis of interface by using optical microscope(OM),X-ray diffraction(XRD),scanning electronic microscopy(SEM)shows that the mutual diffusion occurs between Fe and Cu,and leads to the generation of compound,which,however,does not affect the performance.