Effect Of Cold Pressing On Residual Stress And Properties Of Corrugated Surface Aluminum Alloy

For large 7050 aluminum alloy components,the solution hardening process can obtain excellent mechanical properties and performance,but the quench residual stress generated by the large temperature gradient of the surface and core of the component during quenching cooling reaches 200 MPa or more.This high stress state will not only Affect the use performance of the components,and at the same time cause dimensional defects or even scrap parts in the subsequent machining process.Therefore,effective control and reduction of quenching residual stress has become one of the problems faced by current rese arch and application of aluminum alloys.In this paper,the effects of cold pressing on the quenching residual stress of different corrugated aluminum alloy parts are systematically studied by the combination of finite element simulation and physical experiments,and the effects of cold deformation and corrugation parameters on the residual stress of cold pressure reduction are further explored.Finally,the correlation between the sample thickness and the optimal corrugation parameters is derived.The main contents and conclusions of the paper are as follows:(1)The effect of cold pressing on the quenching residual stress of symmetrical corrugated aluminum alloy parts was studied.The generation and evolution of residual stress in the quenching-cold pressing process of the symmetrical corrugated surface specimens were simulated and the residual stress test was carried out by X-ray diffraction.The results show that the surface residual compressive stress of the symmetrical corrugated sample after quenching is fluctuating with the ripple,and the residual stress is between-120 and-90 MPa.After cold pressing,the residual stress in the longitudinal direction is compressive stress or small tensile stress,and the residual stress in the width direction is “alternating tension and compression”,wherein the peak is compressive stress,the trough is tensile stress,and the residual stress value is reduced to-Between 65~40MPa.The deformation amount and corrugation parameters have a significant effect on the cold stress reduction residual stress effect.The 3% deformation amount,the corrugation height is 5% of the sample thickness,and the corrugation period is twice the thickness of the sample to obtain the best stress reduction effect.After cold pressing,the metallographic structure of the sample is mainly fibrous grains along the direction of corrugation,and the peak performance is lower than that of the trough.(2)The effect of cold pressing on the quenching residual stress of corrugated corrugated aluminum alloy parts was studied.Combined with finite element simulation and physical test,the generation and evolution of residual stress during the quenching-cold pressing process of corrugated corrugated surface specimens were analyzed.The results show that the residual stress of the surface after quenching has no obvious change along the corrugation,and the residual stress is between-115MPa~-100 MPa.The residual stress distribution law of the sample after cold pressing is basically the same as that of th e symmetric corrugated sample.When the cold pressing deformation is 3%,the corrugation height is 5% of the sample thickness,and the corrugation period is twice the thickness of the sample,the most Excellent stress reduction effect.After cold pressing,the peak wave trough position performance of the sample is basically the same,and the metallographic structure is mainly undeformed equiaxed grains,which makes the sample have better elongation.(3)The correlation between sample thickness and optimal c orrugation parameters was studied.When the thickness dimension of the sample changes,the corrugation height is 5% of the thickness of the sample,and the corrugation period is twice the thickness of the sample,so that the best stress reduction effect ca n be obtained.