Experimental Study Of Plasma Arc Surfacing On The Surface Of Deep-shovel Point

Deep-shovel point for deep-loose work in the plow pan receives intense abrasive wearcoming from this soil layer, which has affected the agricultural production efficiency, and createdthe nonessential material loss and the energy waste. On the domestic and foreign enhancing thewear resistant to the agricultural machinery part through the surface treatment is studied little atpresent, therefore there is large space for research on its wear resistance from the anti-frictionmaterial and the metallurgy strengthening method.This article taking plasma arc properties as theoretical basis, with surfacing technology formetallurgical surface strengthening method, was Fe90iron-based self-fluxing alloy powdersurfacing treatment on the deep-shovel point homemade of vermicular cast iron by plasma arc.This paper studied4main factors in plasma arc surfacing technology: surfacing current,surfacing speed, plasma flow rates and the powder feeding rate, having effect on themicrostructure and performance of surfacing layer, and used orthogonal experimental designmethod with4facts and3levels, taking surface Rockwell hardness of surfacing layer asevaluation indexes to optimize4more deeply influenced process parameters above, through thesurface hardness test, the metallographic analysis, X-ray diffraction analysis, wear resistance andSEM analysis of the surfacing layer, concluded such as conclusions as follows:（1） Optimum process parameter programme is: surfacing current90A, surfacing speed16cm·min^-1, plasma flow rates0.6L·min^-1and the powder feeding rate40g·min^-1. Orthogonalexperimental results were carried on the range and variance analysis, obtaining the influence ofthe various parameters in order of size: surfacing speed> the powder feeding rate> surfacingcurrent> plasma flow rates.（2） The dilution ratio and deposit rate of surfacing layer calculated respectively is11.5%and89.1%, both in the ideal range.（3） The average hardness of the surfacing layer with multiphase alloy materials enhancesabout5times more than the parent metal; the major phase components of the surfacing layer iscomposed of the Carbon Chromium Iron (CrFe₇C_0.45), the Chromium Carbide （Cr₃C₂） and theSuessite （Fe₃Si）; the layer microstructure is primary carbide+low-carbon martensite+eutecticcast structure. The abrasive wear test indicated that the relative wear resistance of the surfacingcube is2.6; wear resistance has greatly improved. The hard phase in the layer matrix caneffectively delay the micro-cutting of grits, and the anti-abrasive effect has been obvious. Fieldtrials show that, the wear resistance of deep-shovel point the optimal process treatment is2.67times than before, the wear resistance improved significantly.（4） Evaluation of comprehensive benefits concluded that the surfacing shovel pointenhanced wear resistant and reduced the subsoiling operation cost, obvious comprehensiveeconomic benefit.