The Research To Control The Heat-treatment Distortion Of Shell-body

Distortion is an unavoidable phenomenon in the process of heat-treating. It is one of the two difficult problems on heat-treatments nowadays.Combined theory with application, numerical simulation in quenching cooling process with experiment, the study on heat-treating distortion control of shell-body is carried out to obtain the law of heat-treating distortion and find out the method to reduce and control the distortion. The results show:1. The numerial simulation in quenching cooling process shows the location and the trend of the shell-body distortion. This paper points out that the technology optimization of the clamp structure, vertically hanging parts and the flow of cooling oil help to reduce the distortion.2. To minimize the distortion,norrnalizing(890℃)-annealing(710℃) is carried out as preheat-treating.3. The new quenching-temper process (the precooling quenching process is 650 ℃ /lh preheat, 860 ℃ /48min — 530 ℃ /30min oil cooling, 620 ℃ /2. 5h temper)can ensure ordinary mechanical properities, reduce heat-treatment distortion.4. The vacuum treating not only reduces the distortion but improves the parts' surface quality.5. The location that will be welded has been strengthened so as to reduce the distortion before welding.6. The welding process and the new quenching-temper process is suitable for part 1 and part 2, and the points keep mechanical properties.This task has completed and has got across the examination of the third class award of the army science and technology advancement. This paper pointsout some new methods on heat-treating distortion control of shell-body. The application of this positive results has helped to control the heat treatment distortion, keep the fine quality of the products, and raise production efficiency. No one is scraped because of heat-treatment distortion in more than 140 parts (1), and 50 parts(2).