Effect of interlayer residual stress on microstructure and properties of sandwich composite plate
Adding a filling interlayer between stainless steel composite plates by interlayer vacuum coating technology will produce interlayer residual stress.In the subsequent hot rolling process,the microstructure and mechanical properties of the composite plates may be changed due to the influence of interlayer residual stress.The residual stress between the layers of the stainless steel clad plate is generated by the combined action of the thermal stress and the phase transition stress during the solidification process of the filling interlayer.The residual stress between the layers is eliminated by heat treatment before rolling.The heat treatment process before rolling is formulated by combining numerical simulation and experimental verification.Two kinds of stainless steel clad plates with and with-out eliminating residual stress between the layers are prepared by interlayer vacuum differential pressure coating,heat treatment before rolling and hot rolling experiments.The effects of residual stress on the microstructure and properties of the clad plate are analyzed by metallographic observation,hardness test,interface energy spectrum scan-ning,tensile shear and other characterization and performance test experiments.The results show that the rolling pretreatment process to eliminate the residual stress between layers is heating to 400 ℃,holding for 3.5 h and slow cooling under the condition of ensuring the same structure of base layer,interlayer and composite layer.After pre-rolling treatment,the residual stress between layers is reduced by 96.3％.Compared with the composite plate with-out eliminating interlayer residual stress,the interlayer stress of the composite plate with eliminating interlayer resid-ual stress is significantly enhanced after rolling,and the grain is refined by 81.7％.At the same time,eliminating in-terlayer residual stress can increase the shear strength of the composite plate by 13.3％,the tensile strength by 3.9％,the elongation after fracture by 4％and the microhardness of the interlayer interface by 3.5％.The research content of this paper improves the overall performance of the sandwich composite plate with filling by eliminating the residual stress between the layers,which can provide theoretical guidance for the improvement of the performance of the related casting forming components,and expand the new idea for the further popularization and application of the process.
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