Solid solution treatment refers to the heat treatment process in which the supersaturated solid solution is obtained by heating the alloy to the high temperature single-phase region and keeping the temperature constant so that the excess phase can be dissolved into the solid solution and then cooled rapidly.

Solid solution treatment of steel tubes

Principle of solution treatment:

The purpose of solid solution treatment is to dissolve carbides and gamma’in matrix to obtain uniform supersaturated solid solution, so as to facilitate the precipitation of fine and uniformly distributed carbides and gamma’ strengthening phases during aging, and to eliminate the stress caused by cold and hot working, so as to recrystallize the alloy. Secondly, the solution treatment is to obtain appropriate grain size to ensure the creep resistance of the alloy at high temperature. The temperature range of solid solution treatment is about 980 ~ 1250 (?) C. It is mainly selected according to the precipitation and dissolution law of the phases in each alloy and the application requirements, so as to ensure the necessary precipitation conditions and certain grain size of the main strengthening phases. For long-term high-temperature alloys, it is necessary to have good high temperature durability and creep properties. Higher solution temperature should be chosen to obtain larger grain size. For medium-temperature alloys which require better room temperature hardness, yield strength, tensile strength, impact toughness and fatigue strength, lower solution temperature can be used to ensure smaller grain size. In high temperature solid solution treatment, all kinds of precipitated phases dissolve gradually and the grains grow at the same time. In low temperature solid solution treatment, not only the main strengthening phases dissolve, but also some phases may precipitate. For alloys with low supersaturation, a faster cooling rate is usually chosen; for alloys with high supersaturation, air cooling is usually used.