15CrMo Alloy Plate Has Certain Resistance To Hydrogen Corrosion

　　The metal structure of 15CrMo alloy steel plate is martensite, has good oxidation resistance at around 650 degrees Celsius, has good heat strength below 600 degrees Celsius, and has good shock absorption and thermal conductivity. It is widely used in steam turbines. However, 15CrMo plates have a large tendency to harden and have poor weldability. 5-70MM thick 15CrMo plates can be rolled futures.

　　Features of 15CrMo steel plate: It has good oxidation resistance, corrosion resistance and texture stability. The heat strength is high and the process performance is good.
 

　　15CrMo alloy plate is a pearlitic heat-resistant steel with high heat strength (δb≥440MPa) and oxidation resistance at high temperature, and has certain resistance to hydrogen corrosion. Due to the high content of Cr, C and other alloying elements in the steel, the hardening tendency of the steel is obvious and the weldability is poor.

　　Therefore, the preheating temperature was selected to be 150 °C. The test piece is heated by the oxygen-acetylene flame. Firstly, the temperature of the surface of the test piece is roughly judged by the temperature measuring pen (estimated by the change of the color of the handwriting), and finally measured by a semiconductor thermometer, and at least three points should be selected for the measurement point. In order to ensure that the test piece as a whole meets the required preheating temperature.
 

　　15CrMo Alloy Plate Welding

　　When welding, the first layer is made by manual tungsten argon arc welding. In order to avoid the depression on the back side of the weld at the back weld, the inner wire is used for wire feeding, that is, the wire is fed from the pipe through the gap. The remaining layers are welded by electrode arc welding, and 6 layers are welded together, one weld bead per weld layer.

　　It is feasible to use two welding schemes for the welding of 15CrMo steel thick-walled high-pressure pipes. In order to ensure that the weld bead performance is matched with the base metal and has high heat strength, the effect of the scheme I is better, and the key is to strictly control the post-weld heat treatment process.

　　Although the post-weld heat treatment can be omitted, the possibility of weld migration at the high temperature and the weld seam is not negligible, so it can only be used cautiously after heat treatment after welding.

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