In order to improve the hardness of carbon steel hot-pressed elbows, there are several methods:
Quenching of hot-pressed elbows: Quenching can increase the strength and hardness of steel, but reduce its plasticity. Quenching agents commonly used in quenching are: water, oil, alkaline water and salt solutions, etc. Normalizing of hot-pressed elbows: it can eliminate the reticular cementite of hypereutectoid hot-pressed elbows. For hypo-eutectoid hot-pressed elbows, normalizing can refine the crystal lattice and improve the comprehensive mechanical properties. It is more economical to replace the annealing process with normalizing for the parts.
Tempering of hot-pressed elbows: tempering is divided into three types: high-temperature tempering, medium-temperature tempering and low-temperature tempering. Tempering is often used in conjunction with quenching and normalizing. Its purpose is to eliminate the internal stress generated by quenching, reduce hardness and brittleness, and obtain the expected mechanical properties. Aging treatment: In order to eliminate the size and shape changes of precision measuring tools or molds and parts during long-term use, it is often performed after low-temperature tempering (low-temperature tempering temperature 150-250°C) before finishing.
Reheat the workpiece to 100-150°C and keep it for 5-20 hours. This treatment to stabilize the quality of precision parts is called aging. It is particularly important to perform aging treatment on steel components under low temperatures or dynamic load conditions to eliminate residual stress and stabilize the structure and size of hot-pressed elbows. Quenching and tempering treatment: The heat treatment method of high-temperature tempering after quenching is called quenching and tempering treatment. High-temperature tempering refers to tempering between 500-650°C.
Carbon steel elbow quenching and tempering can adjust the performance and material of the steel to a large extent. Its strength, plasticity and toughness are all good, and it has good comprehensive mechanical properties. Annealing of carbon steel hot-pressed elbow: the hot-pressed elbow is heated to a temperature and kept for a period of time, and then allowed cooling slowly, which is called annealing. The annealing of the hot-pressed elbow is a heat treatment method in which the steel is heated to a temperature at which a phase transition or partial phase transition occurs, and then slowly cooled after heat preservation.
The purpose of annealing is to eliminate structural defects, improve the structure, homogenize the composition and refine the grains, improve the mechanical properties of the hot-pressed elbow, and reduce the residual stress; at the same time, it can reduce the hardness, improve the plasticity and toughness, and improve the cutting performance. Therefore, annealing is not only to eliminate and improve the structural defects and internal stress left over from the previous process but also to prepare for the subsequent process. Therefore, annealing belongs to the heat treatment of semi-finished products, also known as a pre-heat treatment.