The Effect Of Ultrasonic Roll Extrusion On The Surface Properties Of ZG20SiMn Steel

ZG20Si Mn alloy steel has been widely used in various fields of modern industry because of its excellent forging performance and mechanical processing performance,such as large hydraulic turbine main shafts,beams,cylinders,piston cylinders and other parts.In view of the fact that the working conditions of such parts are at high speed and heavy load,and the environment is relatively harsh,the surface is prone to corrosion,wear,cracks and other hidden dangers that seriously affect the safety of machinery and equipment,and the maintenance of such equipment is difficult and costly,so ZG20 Si Mn is increased The fatigue resistance,surface characteristics and wear resistance of alloy steel are of great research significance.In this paper,we first use ABAQUS to establish a numerical simulation model of ultrasonic roll extrusion finite element simulation,extract and solve the residual stress value and equivalent plastic strain under different processing parameters,and discuss and analyze the influence of different processing parameters on it.Ultrasonic roll extrusion of ZG20 Si Mn alloy steel is strengthened by using the Huayun Haucken HVMG500 series ultrasonic roll extrusion vertical machining center;selecting process factors: extrusion force,pressing amount,amplitude,processing times,and strengthening test processing.After strengthening,the surface characteristics of the strengthened samples were analyzed with Vickers hardness tester,roughness meter,X-ray powder diffractometer and other analytical instruments.Then,using the MMG-10 friction and wear testing machine,the optical reading precision balance,scanning electron microscope were used to compare and analyze the wear amount,friction coefficient and surface wear morphology of the original sample and the strengthened sample.Material wear resistance effect.The main findings are as follows:After the ultrasonic surface roll extrusion treatment,all the residual compressive stress is placed on the surface layer,and the depth of the impact of the squeezing force on the residual stress is more symmetrical with respect to the change in the amount of depression,and as the depth of the workpiece surface compressive stress increases Reduced,the surface layer is introduced with a larger value of residual stress,the residual stress is-349.8MPa,and the residual compressive stress is mainly within 1.5mm of the surface layer;the residual stress value measured by different compression force tests is measured by the test value The maximum is-385.04 MPa,and the simulation error is 9.15%.The error between the simulation results and the test results is within the range,indicating the correctness of the finite element model;with the increase of the extrusion force,the thickness of the residual compressive stress surface layer also increases;Through different parameters to the degree of equivalent plastic strain,the degree of work hardening of the material is characterized.Through the orthogonal analysis and calculation of the test results,the primary and secondary rules of the influence of process parameters such as squeezing force,pressing amount,amplitude and frequency on the surface hardness and surface roughness are obtained.The process parameters for obtaining better surface hardness are: extrusion pressure 0.5 MPa,pressing amount 0.5 mm,amplitude 4 ?m,and 4 passes;the process parameters for obtaining lower surface roughness are: pressing force 0.5 MPa,pressing Amount 0.5mm,amplitude 8?m,4 times processing.Through the friction and wear test of the original sample and the ultrasonic surfacestrengthened sample,the wear resistance of the material is evaluated by the change of weight loss and friction coefficient before and after wear,and the morphology of the sample after wear is observed and analyzed.Under the same abrasion conditions,the ultrasonically enhanced sample reduced the friction coefficient by 37.75% compared to the original sample,the abrasion amount was only 0.1053 g,the weight was reduced by 3.7 times,the contact surface wear did not show obvious grooves;at the same time,the form of wear also produced a huge The change,from the initial serious adhesion and fatigue wear to the slight abrasive wear,significantly improves the wear resistance.The analysis of the wear test of the samples under different pressing forces shows that when the pressing force is 0.30 MPa,the amount of wear and the friction coefficient are the lowest,and the material wear resistance performance is the best.