Hot bend annealing is a heat the steel to the phase change or part of the phase transition temperature, slow cooling after heat preservation heat treatment method. The purpose of annealing is to eliminate tissue defects, improve the organization make composition uniformity and fine grains, increase mechanical properties of the hot pressing elbow, reduce residual stress; Can decrease the hardness at the same time, improve the plasticity and toughness, improve machinability. So before annealing in order to eliminate and improve both the legacy of tissue defects and internal stress, and to prepare for the follow-up process, so the annealing is belong to the intermediate heat treatment, also called heat treatment in advance.
Carbon steel elbow quenching
Quenching is carbon steel elbow heated to above the critical temperature, heat preservation for a period of time, then quickly into the quenching medium, the temperature plummeted, rapid cooling, at the rate of greater than the critical cooling rate, which is mainly composed of martensite and unbalanced heat treatment method of the organization. Can increase strength and hardness of the steel quenching, but to reduce its plasticity. That is commonly used in quenching hardening agent are: water, oil, caustic soda, and salt solution, etc.
Carbon steel elbow is fire
Normalizing is carbon steel elbow heated to above the critical temperature, all made of steel elbow into homogeneous austenitic, and natural cooling method of heat treatment in air. It can eliminate the net cementite hypereutectoid hot-pressing elbow to the hypoeutectoid hot-pressing elbow normalizing can refine crystal lattice, improve comprehensive mechanical properties, low requirements for the parts use the normalized instead of the annealing process is more economic.
Source: Zhejiang Yaang Pipe Industry Co., Limited (www.yaang.com)
