What is solution treatment
What is solid solution treatment
solution treatment ( solution treatment) refers to the heating of the alloy to a high temperature single-phase zone to maintain a constant temperature, so that the surplus full phase after being dissolved in solid solution, it is rapidly cooled to obtain a heat treatment process for supersaturated solid solution.
Because the operation process is similar to quenching, it is also called"Solution Quenching". It is suitable for alloys with solid solution as the matrix and the solubility changes greatly when the temperature changes. First, the alloy is heated to a suitable temperature above the solubility curve and below the solid phase line for a certain period of time to dissolve the second phase into the solid solution. Then quickly cool in water or other media to suppress the second phase re- precipitation, you can get a supersaturated solid solution at room temperature or a solid solution phase that usually exists only at high temperatures. As it is thermally metastable, desolysis or other transformations will occur under appropriate temperature or stress conditions. Generally, it is a preliminary heat treatment, which is used to prepare the best conditions for subsequent heat treatment.
Solid solution treatment is to dissolve carbides in the matrix, γ' equal to obtain a uniform supersaturated solid solution, which is convenient for re-precipitation of fine particles and uniformly distributed carbides and γ during aging.' and other strengthening phases, while eliminating the stress caused by cold and hot processing, so that the alloy recrystallization. Secondly, solution treatment is to obtain suitable grain size to ensure the high temperature creep resistance of the alloy. The temperature range of the solution treatment is approximately between 980 ℃ and 1250 ℃, it is mainly selected according to the phase precipitation and dissolution law and application requirements in each alloy to ensure the main strengthening. Necessary the precipitation conditions and a certain grain size. For long-term high-temperature use of alloys, good high-temperature durability and creep properties are required. Choose higher solid solution temperature to obtain a larger grain size; For medium warm use and requires better room temperature hardness the alloy of degree, yield strength, tensile strength, impact toughness and fatigue strength can be used with lower the solution temperature, to ensure a small grain size. During the high-temperature solution treatment, various precipitated phases are gradually dissolved, and the grain grows; During the low-temperature solution treatment, not only the main strengthening phase is dissolved, but also some phases may be precipitated. For alloys with low supersaturation, a faster cooling rate is usually selected; For alloys with high supersaturation, it is usually air cooling.
