Objectives: 1. Reduce hardness, improve plasticity, improve cutting and pressure processing performance; 2. Refine grain, improve mechanical properties, prepare for the next step; 3. Eliminate internal stress generated by cold and hot processing.Application points: Normalizing is usually used as a pre-heat treatment process for forgings, welded parts and carburized parts. For low-carbon and medium-carbon carbon structural steels and low-alloy seamless steel pipes with low performance requirements, it can also be used as the final heat treatment. For general medium and high alloy steels, air cooling can lead to complete or partial quenching and therefore cannot be used as the final heat treatment process.
Purpose: Quenching is generally used to obtain high-hardness martensite structure. Sometimes, when quenching some high-alloy steels (such as stainless steel and wear-resistant steel), it is to obtain a single uniform austenite structure to improve wear resistance and corrosion resistance.Application points: 1. Generally used for carbon steel and alloy steel with carbon content greater than 0.3%; 2. Quenching can fully exert the strength and wear resistance potential of steel, but at the same time it will cause great internal stress. To reduce the plasticity and impact toughness of steel, it is necessary to temper to obtain better comprehensive mechanical properties.
4. Seamless steel pipe tempering operation method: reheat the seamless steel pipe after quenching to a temperature below Ac1, and after cooling, cool in air or oil, hot water and water.Objective: 1. Reduce or eliminate the internal stress after quenching, reduce the deformation and cracking of the workpiece; 2. Adjust the hardness, improve the plasticity and toughness, and obtain the mechanical properties required for the work; 3. Stabilize the workpiece size.