NEW METHOD FOR EVALUATING THE DEPTH OF HARDENED ZONE OBTAINED THROUGH LASER

QUENCH

Ye Yunxia  Zhang Yongkang

(Mechanical Engineering College, Jiangsu University, Zhengjiang 212013)

Li Jin

(Zhenjiang Watercraft Institute, Zhenjiang 212013)

Abstract: It is theoretically analyzed the invalidity of the simple model for evaluating the hardened depth obtained through laser quench, in which the isothermal line of critical temperature for perlite changing into autensite is taken as the hardened depth. However at the critical temperature isothermal line, C atoms can’t diffuse adequately and then material there can’t be effectively hardened accordingly. Based on the said theoretical analysis, a new model(Dt model) is proposed. In the new model, Fourier thermal conductivity theory and time space Dt, ensuring the adequate diffusion of C atoms, are used to evaluate the dimensions of the hardened zones. The new model has been used to evaluate the hardened depth of laser-quenched HT250, and the theoretical results are verified by the experiments and are more accurate than that of the old model.

Key words: Laser quenching  Hardened zone  Numerical analysis  Martensite

CLC No: TH16

Received 20041029, received in revised form 20050125