Functionally Graded Silicon Alloyed Stainless Steel Coatings on AISI Type 304L Stainless Steel

摘要

An important parameter, influencing performance of reprocessing plants using large amount of nitric acid, is the corrosion resistance of its major constructional material viz. type 304L stainless steel. Increase in Si content of the stainless steel beyond 1.6 wt, percent reportedly enhances corrosion resistance of austenitic stainless steel in boiling nitric acid environments. The present study aims at enhancing corrosion resistance of type 304L stainless steel by laser surface alloying with silicon. Surface alloying was performed by laser cladding 304L stainless steel substrate with premixed powders of AISI 304L stainless "steel and Si. Si concentration was progressively increased from 0.59 wt. percent in the base metal to 2.3 wt. percent on the laser modified surface that exhibited a duplex Microstructure of (gamma + alpha). Corrosion studies in 6 N HNO_3 indicated that surface modification with Si and Si_3N_4 enhanced the corrosion resistance.