AISI 4140 high strength steel performance,Heat treatment process

AISI 4140 steel belongs high strength steel which has high strength and toughness,no obvious temper brittleness,high temperature and high creep strength and lasting strength,it has a higher fatigue limit and anti-impact ability after quenching and tempering treatment,and low temperature impact toughness is good. AISI 4140 steel is suitable for manufacture large and medium-sized plastic molds with a certain strength and toughness.Such as locomotive traction with a large gear,supercharger transmission gear,rear axle,by the great load of the connecting rod and spring clip.
Heat treatment process:
Heat treatment is normalizing + quenching + tempering
1. Normalizing:put into the furnace heated to 900 ℃ ~ 930 ℃, the thickest cross-section per inch in the temperature keep one hour,air-cooled.
2. Heating to 860 ℃ ~ 885 ℃ temperature austenitizing,the thickest cross-section per inch in the temperature keep one hour.
3. Normalizing or oil quenching,cooling to a maximum temperature of 121 ℃
4. At the temperature of the following mechanical properties can be achieved under the tempering,the thickest cross-section per inch in the tempering temperature keep one hour, tempering temperature range of 640 ℃ ~ 680 ℃.

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