A、0.25% B、0.0.35% C、0.50%
A、0.035,0.035 B、0.045,0.050。 C、0.035,0.050
A、合金結(jié)構(gòu)鋼 B、合金工具鋼 C、碳素結(jié)構(gòu)鋼