42CrMo4 1.7225 SteelNumber
42CrMo4 1.7225 SteelNumber
42CrMo4 1.7225 SteelNumber
42CrMo4 1.7225 SteelNumber
42CrMo4 1.7225 SteelNumber

42CrMo4 1.7225 SteelNumber

Chemical composition Carbon C: 0.38 ~ 0.45% Silicon Si: ≤0.40% Manganese Mn: 0.60 ~ 0.90% Sulfur S: Allowable residual content ≤0.035% P: Allowable residual content ≤0.035% Chromium Cr: 0.90 ~ 1.20% Molybdenum Mo: 0.15 ~ 0.30%

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Product Introduction

42CrMo4 1.7225 SteelNumber

What is the gas content of 42CRMO4 steel?

The gas in steel is a general term for oxygen, nitrogen, hydrogen and other gases in the medium absorbed during chemical and electrochemical reactions on the surface of steel in smelting, welding or steel. The gas in steel has an adverse effect on the properties of steel, and its content should be strictly controlled

Oxygen in steel

Steelmaking itself is an oxidation process. Although the deoxidizers such as ferromanganese, ferrosilicon and aluminum are added in the late period of steelmaking, some oxygen is still dissolved in the steel.

Oxygen is generally dissolved in ferrite, or the formation of FeO, SiO2, MnO, Al2O3 and other oxides (that is, non-metallic inclusions in steel), so that the tensile strength, plasticity and toughness of 42CrMo4 steel are reduced. Especially in the presence of inclusions, the fatigue strength of 42CrMo4 steel decreases and the cold and hot workability deteriorates.

Therefore, oxygen control technology such as VD deoxidation must be strictly used to make the oxygen content of 42CrMo4 steel less than 20ppm, or even lower.

Nitrogen in steel

In steelmaking, molten steel absorbs nitrogen from the air. Some dissolve in ferrite and some become nonmetallic inclusions. When 42CrMo4 steel does not contain Al, Ti, Zr and other elements, most of the nitrogen and iron form a needle-like compound Fe4N. Although the presence of Fe4N improves the strength of 42CrMo4 steel, it greatly reduces its plasticity and toughness.

By preventing LF nitrogen absorption technology and improving the VD denitrification rate, these two methods can effectively reduce the nitrogen content, which can effectively control the nitrogen content below 90ppm.

Hydrogen in steel

The solubility of hydrogen in steel decreases significantly with decreasing temperature. When hydrogen is present in its atomic state, it dissolves into the Spaces of iron. When the dissolved hydrogen in the steel exceeds 3 ml per 100 grams, it will exist in a molecular state, and hair-like cracks appear in the internal cross section of the ingot or forging, which is called cracking. They look like oval silvery white spots, so they are also called white spots.

White spots make steel hydrogen brittle. Low carbon steel is not easy to form white spots, but medium carbon alloy steel (such as AISI 1045 steel, C55 steel), especially medium carbon nickel chromium molybdenum steel (such as 34CrNiMo6 steel, 30CrNiMo8 steel, AISI 4340 steel), the most sensitive to hydrogen embrittling. For 42CrMo4 steel, it is also easy to form white spots, resulting in material cracking.

The VD vacuum degassing technology can effectively remove hydrogen. In order to avoid embrittleness, 42CrMo4 steel can also be annealed at about 650 ° C to diffuse hydrogen from the steel, eliminate the susaturated state, and achieve the purpose of removing hydrogen. Generally, the hydrogen content can be controlled below 2.0ppm

42CRMO4/DIN 1.7225 Heat treatment

42CrMo4/DIN 1.7225 Normalizing and annealing of steel

When 42CrMo4 steel needs to improve its overall performance, it is usually achieved by heat treatment. Before the final heat treatment, we first consider the preliminary heat treatment, the conventional methods include normalizing and annealing. Let's talk about the differences and characteristics of 42CrMo4 annealing and normalizing to help us choose when facing different requirements.

Different effects and purposes

42CrMo4 normalizing is mainly to refine the grain, homogenize the structure, and prepare the structure for the final heat treatment. The annealing time of 42CrMo4 steel is generally arranged after forging, hot rolling and welding, mainly to reduce the internal stress of the organization. Material, soften the structure, improve the turning performance.