Base material:

(1) 38CrMoAlA(JIS SACM645)

(2)42CrMo(AISI 4140)

Treatment process:

1. Heat treatment

2. Nitriding treatment

Technical parameters:

1. Nitriding depth: 0.4mm-0.6mm

2. Nitriding hardness: 850-950hv

3. Nitriding brittleness: ＜ = 1

4. Surface roughness: Ra0.4

5. Straightness of screw: 0.015mm