PURPOSE: To obtain a valve which has superior cavitation and erosion resistance by forming a phase or austenite phase cong. a prescribed amount of Mn to Cr- Ni stainless steel on a surface layer where wear is caused by water or steam.
CONSTITUTION: At least a cavitation and erosion wear part of a valve, a surface layer consisting of ≤0.2wt% C, ≤2wt% Si, 10W20wt% Cr, 0.5W10wt% Ni, >2 and ≤20wt% Mn, and <2wt% Mo, and ≥1 kind among 0.02W0.3wt% N, 0.01W 0.1wt% Nb, and 0.5W5wt% Co at need and iron for the remainder is formed by build-up welding. For this purpose, C forms a phase and an austenite phase together with Mn and Ni to improve caviation and erosion resistance, and Nb and Co further improve the properties. The coexistence of a ferrite phase deteriorates the properties greatly to the contrary, so its formation should be avoided.
YAMAMOTO MASAO
KAWAI MITSUO
