A.>0.25% B.0.25%~0.6% C.>0.77%
A.S≤0.035%,P≤0.045% B.S≤0.035%,P≤0.035% C.S≤0.025%,P≤0.035%
A.回火馬氏體 B.回火索氏體 C.珠光體 D.回火貝氏體