Features and application criteria: (JIS 4404) SKT4 steel with good toughness, strength and high wear resistance. It at room temperature and 500 ~ 600 ℃ at almost the same mechanical properties. Heated to 500 ℃, can still hold about the hardness of HB300. As the steel contains molybdenum, which is not sensitive to the temper brittleness. Slowly cooled down from 600 ℃ after the impact toughness is only slightly reduced.
 
SKT4 steel has good hardenability. 300mm × 400mm × 300mm chunks of steel materials, oil quenched from 820 ℃ and 560 ℃ tempering, the hardness of some cross-section of almost the same.
 
The various kinds of steel used to make large and medium-sized forging die.
 
This kind of steel is easy to form the white point, the need for strict control of the smelting process and the cooling system after rolling forging
 
The main technical parameters
After quenching: 58
Quenching temperature ℃: 830 ~ 860
Delivery status: annealing HB ≤ 241
Coolant: Oil Oil

Chemical composition of carbon C: 0.50 ~ 0.60

Si Si: ≤ 0.40

Manganese Mn: 0.50 ~ 0.80

Sulfur S: ≤ 0.030

Phosphorus P: ≤ 0.030

Chromium Cr: 0.50 ~ 0.80

Ni-Ni: 1.40 ~ 1.80

Copper Cu: to allow the residual content of ≤ 0.30

Vanadium V: allow the residual content of <0.2

Mo Mo: 0.15 ~ 0.30

Mechanical properties
Hardness
Annealing, 241 ~ 197HB, indentation diameter of 3.9 ~ 4.3mm

Heat treatment and microstructure specifications:

Standard heat treatment: quenching, 830 ~ 860 ℃ oil cooling.

Delivery status: delivery of steel in the annealed condition.

The main purpose
Suitable for manufacturing complex shapes, large impact load, operating temperature is not too high, side length> 400mm medium-sized forging die and trimming die. For the manufacture of the general shape of a simple manufacturing process smelting steel vacuum refining process to ensure purity; use of the large professional heat treatment to pre-hardened steel for best results, uniform hardness distribution.