Through the analysis of the white spot defect of 42CrMo4 steel plate, the control and repair methods are summarized:
(1) Measures to reduce H content in 42CrMo4 steel plate in the steelmaking process; increase the end point C content to prevent over-oxidation; increase the stirring strength and argon flow under vacuum; improve the suction capacity of vacuum equipment.
(2) Forging and compacting methods that can reduce the sensitivity of the white point of 42CrMo4 steel plate are adopted in the process. For example, try to use high temperature forging and shorten the distance from the surface of the core forging to increase the diffusion rate of H and the relative area of the forging. Therefore, H is easily precipitated from the inside of the 42CrMo4 steel plate, reducing the possibility of steel white spots.
(3) Strictly control the quality of 42CrMo4 steel plate raw materials to greatly reduce the content of inclusions. According to the H content and cross-sectional size of the forging, a reasonable heat treatment process of 42CrMo4 steel plate is determined to eliminate the residual stress caused by the temperature stress and the uneven deformation during the cooling process.
