Q. F. Wang
,
J. H. Liu
,
Z. Y. Li
,
P. H. Li
,
G. F. Zhou and X. Chen( 1) Huazhong University of Sci. & Tech.
,
Wuhan 430074
,
China 2) Technology Center of WISCO
,
Wuhan 430080
,
China)
金属学报(英文版)
The microstructure and properties of stmulated heat affected zone (HAZ) of laser welded ULCB600 steel were investigate by applying the simulation technique with gleeble - 2000 dynamic thermal - me - chanical simulator.The influence of the preheat condition on the microstructure and properties of simu- lated HAZ of laser welded plate was also studied in order to evaluate the feasibility of reducing arisk that the ductility and toedness of HAZ may be poor by using preheat treatment.The results indicate that the grain size of laser - welded HAZ simulated is very small no matter if there is preheat, the toughness of simulated HAZ is therefore improved comparing to the base metal,and there is no obvious brittle - ductile transition in the range from - 80℃ to 20℃. The TEM analyses of sub -microstruc- ture also discover that microstructure constituent of both simulated HAZ is dominative lath martensite. However, the shaf of martensite is relatively coarse,and the dislocation density is relatively high for simulated HAZ with 200℃ preheat because of slower cooling rate. Combination of these tow factors is responsible for farer bardness and better toughness of simulated HAZ with preheat condition.
关键词:
physical simulation laser beam welding
,
null
,
null
J.F. Sun
,
J. Shen
,
Z. Y. Li
,
J. Jia and Q.C. Li National Key Laboratory of Metal Precision Hot Processing
,
Harbin Institute of Technology
,
Harbin 150001
,
China
金属学报(英文版)
Based on the Newtonian heat transfer formulation and classical heterogeneous nucleation theory, a mathematical model has been established to predict the profile of flight velocity, heat transfer coefficient, temperature, solid fraction and cooling rate of atomizing droplets for a superalloy. The results indicated that above parameters change with different droplet size and flight distance. The changing trend as well as the mechanism for the change are described and discussed.
关键词:
spray forming
,
null
,
null
,
null
