1. DIN1.7225/SAE4140/GB42CrMo, JIS SCM440 alloy steel round bar

2. Hot rolled condition, annealing or harden, black or milled surface

3. Pre-heat treatment:

Annealing: Heat to 840-860 degree, keep 2H, furnace cold, hardness 217HBS MAX

High temperature tempering: Heat to 680-700 degree, air cold, hardness 217HBS MAX

4. Heat treatment:

Normalization: Heating to 840 to 880 degree, maintenance, furnace cooling to 600 degree, then in air.

Stress relieving: After rough heat to 500 degree, maintenance raff. In oven to 400 degree, then in air.

Hardening: Preheating from 600 to 650 degree, austenitizing At 840 to 880 degree, quenching in oil.

Tempering: Heating to 550 - 650 degree and maintenance regime, again depending on the mechanical Properties

5. Hot rolled technology: EAF+LF+VD

6. Ultrasonic test standard: SPE1921-GR3, CLASS C/C or D/D

7. Production leadtime: 7~10 days

Product Feature

Chemical component:

C 0.17-0.23

Mn 0.30-0.60

Si 0.15-0.40

Cr 1.25-1.75

Ni 3.25-3.75

Cu 0.25 MAX

P 0.030 max

S 0.030

Product Specification/Models

Hot rolled condition

16~255*2000~5800 mm

Application

General service industries (petroleum, food, chemical, paper, fertilizer, Fabric, aviation and nuclear)

Fluid, gas and oil transport,

Pressure and heat transmission

Construction and ornament

Boiler heat exchangers