Chemical composition of SK4

Carbon C:0.95 ~ 1.04

Silicon Si: less than or equal to 0.35

Manganese: less than 0.40 Mn

Sulfur: less than 0.030 S

P: less than 0.035 P

Cr Cr: allows residual content less than 0.25, less than 0.10 (manufacturing lead bath quenching steel wire)

Nickel: allows the residual Ni content less than 0.20, less than 0.12 (manufacturinglead bath quenching steel wire)

Cu: allows the residual copper content less than 0.30, less than 0.20 (manufacturinglead bath quenching steel wire)

Note: the allowable residual content of Cr+Ni+Cu is less than or equal to 0.40(manufacturing lead bath quenching steel wire)

Hardness: annealing, is less than or equal to 197HB, the indentation diameter greater than or equal to 4.30mm = 50HRC; quenching, heat treatment and microstructure of SK4 specification

Heat treatment quenching specimen specification: 760 to 780 DEG C, cooling.

Supply hardness:

Soft, semi hard, hard (hard material heat treatment)

The color of the surface:

White, blue, golden color, heat treatment

Delivery state: Steel in annealing state of delivery. By mutual agreement, may also notannealed state of delivery.