| H13 (4CrSMoSiV1), as a new model hot die steel, has excellenthardenability, quenching rigidity and good nature at room and hightemperature. Its service life is longer than the casting die steel(3Cr2W8V).The magnesium alloy casting die through routine heat treatment often showsinactivation of distress chap, severity erosion and mucosity to die in bad workcondition. Consequently, improvement of surface heat treatment technologyof H13 casting die is exigent with wide application of magnesium.The paper applied RE-B-N-C multi-element penetration technology andquenching+temper method to improve the resistance of abrasion, hightemperature oxidation and heat fatigue. The penetration agents consisted ofadmixture of Char and activated carbon, urea and zala, and the activatorsconsisted of soda, ammonium chloride, sodium fluoride, aluminite powder,sodium chloride and creosote thulium. Several apparatus were applied to testsamples, which were NIKO microscope for analysis of compound layer,M-400-H1microhardness instrument for test of penetration layer stiffness,M200 abrasion tester for attrition test of penetration layer, box type furnacefor high temperature oxidation resistant test. Moreover, heat fatigue control experiment were carried out among samples that were obtained through thedifferent methods included quenching+temper, quenching+temper+BNCmulti-element penetration, CrN vacuum ion metallic membrane plating,CrN/AlN vacuum ion metallic-membrane plating, vacuum ion NC multi-element penetration.The results showed that the methods, 930℃×4h (RE-BNC multi-elementpenetration)→1020℃×20min(quenching)→600℃×30min(temper)→550℃×4h(RE-NC multi-element penetration)→180℃×4h(aging treatment) areeffective in the surface strengthening. When the compound of carbonic acidwere put in by 10％, the compound layer thickness reached 95～105μm andthe case hardness reached HV1210 without soft band region. The surfaceattrition rate reduced to 0.028mg/min. The result of heat fatigue controlexperiment shows the surface cracks of RE-BNC multi-element penetrationsample had small changes, and no major cracks and dropped massive texturethrough 2000 tests from room temperature to 700℃. BNC multi-elementpenetration samples had radial cracks through 1500 tests, and had texturedesquamation through 2000 tests. Moreover, vacuum ion metallic-membraneplating and vacuum ion NC penetration samples had cracks and texturedesquamation at the different degree through 300～500 tests. Therefore,RE-BNC multi-element penetration technology is an effective method in thesurface treatment of H13 steel.
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