Stainless steel pipe heat treatment

annealing
The process of heating a stainless steel pipe to a certain temperature, holding it for a fixed time, and then slowly cooling the pipe is called annealing. Specifically speaking, it is a heat treatment process in which the stainless steel pipe is first heated to a temperature that will produce a phase change or a partial phase change, and then slowly cooled after being kept warm for a period of time.
Annealing stainless steel pipes is mainly to remove structural defects in the steel, improve the metallographic structure to make the composition more uniform and refine the grains, enhance the mechanical properties of the pipe, reduce residual stress, and also reduce its hardness, improving the plasticity and plasticity of the steel. Toughness, optimized cutting performance. In general, the annealing process can not only eliminate and improve the structural defects and internal stress left by the previous process during the processing of stainless steel pipes, but also prepare for the subsequent processes. Therefore, annealing is a kind of semi-finished product heat treatment, also known as pre-heat treatment.
Normalizing
Normalizing is a heat treatment process in which the stainless steel pipe is heated above the critical temperature, completely transforming the pipe into a uniform austenite structure, and then naturally cooled in the air. This process can eliminate the network cementite of hypereutectoid steel pipes. For hypoeutectoid steel pipes, normalizing can refine the crystal lattice and enhance the comprehensive mechanical properties of the pipes. It is more cost-effective to use normalizing instead of annealing for parts with low requirements. of.
Quenching
Quenching refers to heating the steel pipe to above the critical temperature, keeping it warm for a period of time, and then quickly putting it into the quenching agent to cause its temperature to drop suddenly and cool it rapidly at a speed greater than the critical cooling rate to obtain an instable material mainly composed of martensite. Thermal Treatment Methods for Equilibrating Tissues. Quenching can increase the strength and hardness of steel pipes, but reduces its plasticity. Commonly used quenching agents in quenching include: water, oil, alkaline water and salt solution, etc.
Tempering
The process of reheating the quenched stainless steel pipe to a certain temperature and then cooling it using a certain method is called tempering. This purpose is to eliminate the internal stress formed by quenching to reduce hardness and brittleness to achieve expected mechanical properties. There are three types of tempering: high temperature tempering, medium temperature tempering and low temperature tempering. Tempering is often used in conjunction with quenching and normalizing.
Quenching and tempering treatment refers to the heat treatment process of high-temperature tempering after quenching. High temperature tempering refers to tempering between 500-650℃. Quenching and tempering can greatly adjust the performance and material of stainless steel pipes. For example, the strength, plasticity and toughness of the pipe are very good, and it has good comprehensive mechanical properties.
Aging treatment refers to the elimination of changes in size and shape of precision measuring tools, molds, and parts during long-term use. The workpiece is often reheated to 100-150°C after low-temperature tempering (low-temperature tempering temperature 150-250°C) and before finishing. ℃, and then keep it for 5-20 hours. This is a process that stabilizes the quality of precision parts and is called aging. It is very important to perform aging treatment on stainless steel pipe components under low temperature or dynamic load conditions to eliminate residual stress and stabilize the structure and size of the pipe.