Effect of hydrogen on 42CrMo4 steel plate

The solubility of hydrogen in 42CrMo4 steel decreases significantly with the decrease of temperature. When hydrogen exists in the atomic state, it dissolves into the interstices of the iron. When the dissolved hydrogen in the steel exceeds 3 milliliters per 100 grams, it will exist in a molecular state, and hair-like cracks will appear on the internal cross-section of 42CrMo4 steel ingot or forging, which is called cracking. They look like oval, silvery-white spots and are therefore also called white spots. White spots make steel hydrogen embrittlement. Low carbon steel is not easy to form white spots, but medium carbon alloy steel, especially medium carbon nickel chromium molybdenum steel is the most sensitive to hydrogen embrittlement. For 42CrMo4 steel, it is also easy to form white spots, causing the material to crack.

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

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