Abstract: Based on the electromagnetic-thermal-microstructure-stress coupling model, the temperature, microstructure and stress variation laws of the 42CrMo steel output flange during induction quenching process were studied, and the reliability of the numerical simulation was experimentally verified by hardening profile comparison and hardness testing. The results show that in the heating stage, the upper and lower sharp corners of the arc transition zone reach the austenitizing temperature earlier than that of the middle position. The heating effect gradually decreases after the temperature of the induction zone reaches the Curie point of the material. The microstructure of flange surface changes from original microstructure to austenite with the increase of temperature. The surface stress of flange is compressive stress in the heating stage, which increases rapidly at the beginning of heating, and then decreases gradually with the increase of internal temperature. In the quenching stage, the temperature drops rapidly, and the surface austenite quickly transforms into martensite. The stress at the surface passes through a short period of tensile stress, and then transforms into compressive stress (axial, radial and tangential stresses are all compressive stresses), among which the radial compressive stress is the largest, about 460 MPa.

Key words: electromagnetic-thermal-microstructure-stress coupled field, output flange, temperature field, phase transformation, hardened layer, residual stress