The Finite Element Analysis Of The Brazing Stress And Distortion Of Dissimilar Material

The cemented carbide has advantages of high hardness, resistant to elevated temperature, corrosion resistant and good wear-resistance. It has been widely applied in the hermetic unit, cutting-tools, die, measuring tools and anti-abrasive components and the effect is notable. But there will exist high residual stress and distortion, even cracks, near to the joint due to the mismatch of material performance during the cooling process of brazing with other materials. To large area cemented carbide cirque, it is easier to generate crack and dehiscence Therefore, it is significant to forecast the residual stress of the brazed workpiece between the cemented carbide and other materials.Nonlinear MARC software was used to analyze the magnitude and distribution of the residual stress and the sensitive area of the joint between the cemented carbide cirque and steel matrix by thermal-elastic-plastic finite element method. The influence of temperature on the material properties were taken into account. The residual stress near the joint was measured by micro-zone X-ray diffraction approach to test and verify the reliability of simulation.The simulation shows that: the effect of axial stress and circumferential stress on the strength of the brazed joint is very little, and radial stress is the main factor of joint damage. The residual stress in the contact surface between brazing seam and cemented carbide is the maximal, and the radial tensile stress reach to the maximum at the place of 0.4mm from the inner side of the cemented carbide, the axial tensile stress is the maximum in the inner side of the contact surface. The area near the inner side of the contact surface between cemented carbide cirque and brazing seam is the most serious damaging area.The effect of joint shape, the filler metal thickness, buffer layer, putting loadand the sizes of the component on the residual stress also were studied by simulation. When there is a notch on the steel matrix the residual stress is much higher than that of without notch on steel matrix due to notch restraint, so the notch is bad to the strength of the joint. The residual stress will decrease with the increase of filler metal thickness, when the thickness is 120 y m, the residual stress is the minimum, then the residual stress will increase with the increase of thickness. There exists an optimal value to the brazing seam;The residual stress will be released greatly by adding buffer layer, and the most suitable size of buffer layer exists. The thinner the thickness of the filler metal layer is, the less the residual stress is, so the filler metal should be thin under the condition of wettting the brazing surface; The residual stress will decrease effectively when put some load on the surface of the cemented carbide; The larger the sizes of component and the brazing area are, the higher the residual stress is.X-2001 two -dimensional stress analyzer was used to measure the surface stress of the steel matrix at the two sides of cemented carbide cirque and upper surface of cemented carbide cirque. The experimental data were compared with the finite element calculations. The finite element calculations were in good agreement with the general trend of the experimental data, and verified reliability of the simulation.