30 CrMo

30CrMo is a kind of alloy steel. It is with high static strength, fatigue limit and impact strength. So it is be used for making sucker rod.

30CrMo is middle carbon alloy steel. It has good technical and mechanical properties and the price is more competitively price. But 30CrMo performance is unstable and mechanical performance can’t meet the requirements of processing problems after heat treatment .

So in order to improve the performance after heat treatment. Then manufacturer need to take effective measure to improve performance.

Treatment of 30CrMo.

1. The amount of ingredients impact on performance.

Normally, the structure of steel determines its performance. The content of Cr has high hardenability and tenacity.

For 30 crmo conditioning treatment, the use of high temperature tempering again after oil quenching, quenching after can use cold water or oil, the tensile strength and yield strength volatile.So the amount of the composition of the steel on the performance of the steel after heat treatment have great influence.

2. Trace elements affect steel performance.

The influence of the addition of alloy elements, the steel is very large. Alloy elements of quenching and tempering condition of steel reinforcement effect is remarkable.

Cr. W. Mo. AL. Si  can improve the heat resistance of steel, of which the Cr can improve the corrosion resistance of steel.

Tempering stability of the alloy elements can improve it, make the carbide precipitation during tempering hardened steel is more small, uniform and stable.

The influence of heat treatment on the performance.

1. Sample size and quenching cooling rate.

Quenching cooling rate affect the organization and performance after quenching. After the water quenching and oil quenching hardness has the very big difference, the sample size is different, the actual is quenching cooling rate is not to play with, so the performance of 30 crmo steel after quenching and quenching medium, there is a close relationship.

2. Tempering temperature.

30CrMo steel and other steel, namely, the increase of tempering temperature strength, hardness, plasticity and toughness.

 

30CrMo chemical composition.

C：0.26-0.34

Si : 0.17-0.37

Mn : 0.40-0.70

S : ≤0.035

P : ≤0.035

Cr : 0.80-1.10

Ni : ≤0.030

Cu : ≤0.030

Mo : 0.15-0.25

 

30CrMo Mechanical Properties.

Tensile strength of sigma b (MPa) : 930 (95) or higher

Yield strength sigma s (MPa) : 785 (80) or higher

Elongation delta (%) : 12 or more

Reduction of area bits (%) : 50 or more

Impact energy Akv (J) : p. 63

 

Application:

This kind of steel is often used in the quenched and tempered state, when carbon content as the center of the steel also can be used as a requirement of the lower limit carburizing steel of high strength.Mainly used in the manufacture of cross section is larger in the medium-sized machinery manufacturing, work under high stress conditions of conditioning parts, such as shaft, shaft, and the high load of wheel, bolts, double-headed bolts, gears, etc.;In the chemical industry used in the manufacture of welding parts, plate and pipe welding structure and work in the medium containing nitrogen hydrogen temperature does not exceed 250 ℃ high pressure pipe;In steam turbine, boiler manufacturing fasteners in the manufacture of work under 450 ℃, 500 ℃  under the high pressure flange and nut, is especially suitable for manufacturing 300 atmospheres, duct work under 400 ℃