Effect of Electrical Discharge Machining on Surface Integrity and Mechanical Properties of H13 Steel
H13 steel was processed by electrical discharge machining.The effects of electrical discharge machining on the microstructure,phase composition,residual stress,microhardness and impact properties of H13 steel were studied.The results show that the surface of H13 steel after electrical discharge machining had some defects,such as molten particle spheres,craters,holes and micro-cracks.The cross-section was divided into white bright layer,heat affected zone,annealing zone and matrix.There were columnar crystals,columnar dendrites,isaemic crystals and eutectic structures in the white bright layer,and the microstructure included martensite,residual austenite,Fe3C,Fe7C3,(Cr,Fe)7C3 and Fe0.3Mn2.7C,etc.Compared with the matrix,the content of carbon and residual austenite increased.The residual stress and microhardness of H13 steel after electrical discharge machining were higher than those of the matrix,and increased first and then decreased,and the maximum values were 575 MPa and 647.3 HV,respectively.After electrical discharge machining,the impact energy of H13 steel was reduced by 35.56％compared with that after grinding machining;there were a lot of tearing edges,dimples,cleavage planes and large scale stripping planes on the impact fracture,and the fracture had quasi-cleavage fracture characteristics.
H13 steelelectrical discharge machiningsurface integritywhite bright layermicrohardnessimpact energy
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