Up-grade through Heat-treatment
Published on:
2022-07-28
The process of Quench and Tempering is important because it improves the mechanical properties, hardness and toughness of the alloy material. The oil and gas drilling industry has for years used quench and tempered steel tubulars for well casing.
1.Quenching and Tempering
The process of Quench and Tempering is important because it improves the mechanical properties, hardness and toughness of the alloy material. The oil and gas drilling industry has for years used quench and tempered steel tubulars for well casing. The quench and tempering process can be affected by several things which may be beyond the control of the heat treater. Some of the common elements are steel type, rolling method, forming processes, weldings, sizing and seam normalizing.
The quenching process starts with heating the steel to a temperature at which it changes the grain structure from ferrite to austenite. It then rapidly cools (quenches) to force the austenite to transform to another shape called martensite. This is the high strength structure of steel and the ultimate goal of the process.
Tempering completes the heat-treating process. It helps relieve the stress induced by quenching. The purpose of tempering is to increase the toughness of steel and alloy steel pipe. Before tempering, quenched steel pipe is very hard but too brittle for the most application. Tempering can improve the plasticity and toughness of steel pipe, reduce, or eliminate the residual stress and stabilize the steel pipe’s size, resulting in quality API comprehensive mechanical properties.
2.Normalizing
Heating the steel pipe above the critical temperature and cooled in the air. Through this normalizing process, the entire tube is changed to the same grain structure; the material stress can be relieved, reducing the brittleness, improving the ductility, strength and toughness of the tubing or casing.
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