in general is to improve the mechanical performance of steel or processing performance. Specific as follows:
1 steel heat treatment annealing
The steel is heated to a certain temperature and heat preservation time, and then makes it slowly cooling, called annealing. Steel is annealed by heating the steel phase change or a portion of a phase change temperature, slow cooling after vacuum heat treatment method. The purpose of annealing, in order to eliminate defects in the organization, improving the organization to make homogeneous and refine the grain, improve the mechanical properties of the steel, reduce the residual stress; at the same time can be reduced to improve hardness, plasticity and toughness, improve the cutting performance. So as to eliminate and improve annealing step from tissue defect and internal stress, and follow-up procedures to be ready, the annealing is a semi-finished products heat treatment, also known as the preliminary heat treatment.
2 normalizing heat treatment of steel
Normalizing is the steel is heated to above the critical temperature, the steel completely converted to homogeneous austenite, and then in the air cooling heat treatment method. It can eliminate the hypereutectoid steel network cementite, for hypoeutectoid steel normalizing can refine the crystal lattice, improve the comprehensive mechanical properties, the less demanding parts in normalizing instead of annealing process is more economical.
3 steel heat treatment quenching
Quenching is the steel is heated to above the critical temperature, holding time, and then quickly into the quenching agent, the temperature plummeted, greater than the critical cooling rate of fast cooling, and to acquire the martensite uneven tissue heat treatment method. Quenching can increase the strength and hardness of the steel, but to reduce the plastic. Quenching quenching agent commonly used are: water, oil, alkali and salt solution.