Large casting parts heat treatment furnace  

The strength level of large castings and forgings, but poor plasticity, toughness, uneven internal organization, density, internal chemical composition deviation is bigger, low thermal conductivity and complex shape, so special attention should be paid to eliminate internal stress in heat treatment, prevent craze, but don’t have to consider the harm of hydrogen. The TTT curve, CCT curve and hardenability curve of the same steel number can be used in the heat treatment process. However, it must be noted that the chemical composition is uneven, the grain size is large and other casting defects are affected.

The types and purposes of heat treatment are:

1. Diffusion annealing (high temperature homogenization annealing). The purpose of this paper is to eliminate or reduce the composition segregation in casting parts, improve some soluble impurities, and make the chemical composition, internal organization and mechanical properties of casting parts uniform and stable.

2. Normalizing and tempering. Through the recrystallization of the internal structure, the strength and toughness are improved, and the casting parts are well integrated mechanical properties, and the cutting performance of the workpiece is improved.

3. The annealing. The size, structure and properties of the casting parts are stable, and the plasticity and toughness of casting parts are improved obviously. The annealing process is easy to operate and the heat treatment stress is small, but the strength and hardness of the workpiece are lower.

4. Conditioning. Due to the great stress of heat treatment during quenching, it should be used carefully. It is only used for the high performance of casting parts, and only after the casting has been sufficiently annealed. The comprehensive mechanical properties of casting parts can be improved greatly by adjusting the quality.

Eliminate stress annealing. The purpose of this paper is to eliminate the internal stresses in the casting parts, the main repair parts, the welding parts, the welding parts and the rough processing stress, so as to prevent the defects from stabilizing the workpiece size. The temperature of the stress annealing must be lower than the workpiece tempering temperature of 10 to 30 degrees Celsius, and the heat preservation time is more than 25 hours (the maximum thickness of the workpiece is the maximum thickness of the workpiece, mm), and then it is cooled in the furnace.