Numerical Simulation And Experimental Study Of Printing Alloy Steel Based On Wire Arc Additive Manufacturing Technology

With the steady development of the manufacturing power strategy of "made in China 2025",the transformation and upgrading of China’s manufacturing industry is accelerating.As one of the advanced intelligent metal manufacturing technologies,wire arc additive manufacturing(WAAM)technology has a broad application prospect.During the WAAM process,complex thermal stress and residual stress evolution occurs at the particular position through periodic reheating and recooling,which can result in delamination of interlayers,causing deformation and cracking of the parts,and reducing the deteriorated performance and poor forming quality.In this thesis,based on the THERMOELASTIC-PLASTIC finite element method and experimental methods,the thermal history and stress evolution of the arc-deposited buildup are studied,which provides the basis for controlling the thermal stress during the deposition process and optimizing the forming process parameters.In this thesis,the forming experiments of single pass and multi-layer 2Cr13thin-walled parts were studied.The temperature field and stress field of thin-walled parts formed in different interlayer idle time and deposition direction are simulated by establishing three-dimensional finite element model.The simulation results have a good agreement with the corresponding experimental results.The results show that the residual tensile stress in the deposit can be reduced by prolonging the interlayer residence time properly.When the interlayer idle time is more than 210 s,the further increase of the interlayer idle time can hardly reduce the stress.S-shaped deposition can improve the uniformity of residual stress distribution and reduce the average stress of the parts.The effects of idle time between passes and four deposition forming path on the thermal history and stress evolution of multi pass single-layer H13 deposited parts were studied.The results show that the residual stress distribution on substrate and deposition can be significantly reduced when the inter pass idle time is extended from0 s to 60 s.when the inter pass idle time is longer than 60 s,the inter pass idle time can not significantly reduce the stress,but also increase the high residual stress area on the deposited parts.For the 2D planar forming path,the area of the high residual stress on the deposited parts is the smallest when the symmetrical S-shaped path isadopted from both sides.When the symmetrical S-shaped path is adopted from the middle to both sides,the transverse residual stress peak value of the deposited parts along the substrate centerline distribution is the lowest and the longitudinal residual stress is the smallest in the interior of the deposited parts.The effects of four deposition paths on the thermal history and stress distribution of multi-pass and multi-layer H13 block were studied.The results show that,for the3 D solid forming path,the high residual stress on the formed block is significantly smaller than that of the other deposition paths when the interlayer cross deposition path is adopted from inside to outside of the layer,and the deformation of the formed block is significantly smaller than that of the other deposition paths.The overall deformation distribution is relatively uniform.