Cavitation erosion and corrosion behaviors of stainless steel 316 laser surface-alloyed with WC

Abstract

Fine WC powder was preplaced on stainless steel 316 by pasting and processed with a high power CW Nd-YAG laser to achieve surface alloying. The composition and microstructure of the alloyed layer and the phases formed were investigated by EDS, SEM, and XRD respectively. The cavitation erosion and corrosion behaviors of the alloyed samples in 3.5% NaCl solution were studied by vibratory cavitation erosion test and potentiodynamic polarization test. Under favorable processing conditions, the cavitation erosion resistance of the alloyed sample could reach more than 30 times that of the as-received 316. On the other hand, the corrosion resistance in general deteriorated. The improvement in cavitation erosion resistance could be attributed to the increase of W in solid solution and to the precipitation of fine carbides, both resulting from the dissolution of the fine WC powder during laser processing. The decrease in corrosion resistance originated from the weakening of the passive film because some Cr precipitated out from solid solution to form metal carbides.Fine WC powder was preplaced on stainless steel 316 by pasting and processed with a high power CW Nd-YAG laser to achieve surface alloying. The composition and microstructure of the alloyed layer and the phases formed were investigated by EDS, SEM, and XRD respectively. The cavitation erosion and corrosion behaviors of the alloyed samples in 3.5% NaCl solution were studied by vibratory cavitation erosion test and potentiodynamic polarization test. Under favorable processing conditions, the cavitation erosion resistance of the alloyed sample could reach more than 30 times that of the as-received 316. On the other hand, the corrosion resistance in general deteriorated. The improvement in cavitation erosion resistance could be attributed to the increase of W in solid solution and to the precipitation of fine carbides, both resulting from the dissolution of the fine WC powder during laser processing. The decrease in corrosion resistance originated from the weakening of the passive film because some Cr precipi...