Numerical Simulation and Experimental Study on Secondary Cold Extrusion Strengthening of Pressed Bush
The ear hole of 7050 aluminum alloy was strengthened by using the second cold extrusion of pressed bush;The effects of the second cold extrusion on the residual stress,plastic deformation,and roughness of the inner surface of the ear hole were studied via X-ray diffractometer,coordinate measuring machine,and roughness meter,and which were verified through finite element simulation.The experimental results show that comparing with that in first cold extrusion,the second cold extrusion of the pressed sleeve can effectively improve the non-uniformity of residual stress at both ends of the sample.As the relative extrusion amount of the second cold extrusion increases,the peak residual compressive stress and the depth of the stress layer increase,and the degree of the plastic deformation increases too,meanwhile the surface roughness of the hole wall decreases.When the relative extrusion amount is 2.5%,the maximum residual compressive stress can reach-400.3 MPa,and there is a residual compressive stress layer of about 14 mm.The inner diameters of the sample end face A and end face B increased by 0.56 mm and 0.54 mm,respectively;the surface roughness of the hole wall decreased by 71.0%.Comparing with the first cold extrusion,the second cold extrusion strengthening forms a deeper residual compressive stress layer and plastic deformation layer along the radial direction of the hole wall,significantly improving the overall service performance of the ear hole.
second cold extrusionpressed bushrelative extrusion amountresidual stressplastic deformation
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