420 plate chemical composition C Mn Si SP Mo Ni Cr 0.15 ~ 0.35 ≤ 1.00 ≤ 1.00 ≤ 0.028 ≤ 0.030 0.60 3.00 11.50 ~ 14.50 factory state soft annealing 420 to about 250HB features applications mirror plastic mold steel corrosion has some wear and corrosion resistance, hardness, its price is lower stainless steel ball in a class for general requirements for stainless steel work environment. 420 stainless steel for all kinds of precision machinery, bearings, electrical, equipment, apparatus, instruments, means of transport, and household appliances. Used for manufacture of anti-air, steam, water and oxidizing acid corrosion of parts