Study On Thermoacoustic Surface Strengthened Processing Technology Of Metallic Materials

Thermoacoustic processing technique is a kind of new surface hardening technology.Compared to other thechniques, it is simple in technics, its cost is also low and easy torealize. But its hardening mechanism is still not understood. Therefore, it has importantvalues both in theory and application. Thermoacoustic processing was carried out for coldrolled industrial pure iron, W6Mo5Cr4V2 steel, 40Cr steel and high chromium cast etc andmany means were adopted to investigate the effect of thermoacoustic processing on theorganization and properties of materials in this article. The result showed that cold rolledindustrial pure iron processed by thermoacoustic impelled dislocation movement under theaction of nonlinear acoustic wave and promoted the process of recovery andrecrystallization. Central-carbon 40Cr steel processed by thermoacoustic after quenchingand tempering could increase their surface hardness and whole plastic.and the depth ofstrengthened coating was up to 3 mm. But after tensile sample was processed bythermoacoustic, its strength had no obvious changes, and even percentage elongation andimpact toughness increased. 40Cr steel after tempering at 550℃was processed bythermoacoustic, which could promote the phase transformation of martensitic to temperedsorbite, meanwhile there was thin and dispersing carbide separated out. W6Mo5Cr4V2steel after three tempering at 550℃was processed by thermoacoustic. After that, the depthof its strengthened coating was up to 2mm, the surface microhardness increased from 800HV to 1100 HV or so, the impact toughness of unnotched specimens increased from 17.5J/cm~2 to 33.1 J/cm~2, and there was very thin and dispersing carbide particles separated outin the surface layer. Thermoacoustic processing could obviously increase the wearresistance performace of materials. W6Mo5Cr4V2 steel after three tempering wasprocessed by thermoacoustic. After that, its wear resistance performace at both room andhigh temperature (500℃) increased. The application performace of aiguille maked by highspeed steel obviously improved and its service life was 3.5 times workpiece whithoutthermoacoustic processing. After high chromium cast was processed by thermoacoustic, atroom temperature by the contactface of GCr15, its wear rate decreased by 40%. Theapplication performace of guiding equipment maked by high chromium cast obviouslyimproved and its service life was over 1.5 times workpiece without thermoacousticprocessing.