Heat Treatment of Precision Casting


Casting for heating and cooling conditions are different, so it has a lot of heat treatment, the following Xiaobian to introduce the main heat treatment.

Casting for heating and cooling conditions are different, so it has a lot of heat treatment, the following Xiaobian to introduce the main heat treatment.

1. Annealing: Annealing is heated to above Acs cast steel 20 ~ 30 degrees Celsius, applicable to all kinds of steel castings.

2. Normalizing: Normalizing is the steel mesh mouth heat to Ac degrees Celsius, 30 ~ 50 degrees Celsius heat preservation, which fully austenitic, heat treatment process and then cooling in still air. The general engineering with carbon steel and thick and large, complex shape of alloy steel castings by normalizing treatment.

3. Quenching: Quenching is heated to the steel castings after austenitizing, maintain a certain time in a proper way of cooling, heat treatment process of martensite or bainite. There is a common water quenching, oil quenching and air quenching etc.. Cast steel after quenching tempering treatment should be timely, in order to eliminate quenching stress and obtain the required mechanical properties.

4. The quenching or tempering: Tempering after normalizing steel is heated to a temperature below Ac, selected, heat preservation time, the rate of cooling suitable, get after normalizing quenching or unstable organization into a stable organization, eliminating quenching (or normalized) stress and improve the steel plastic and the toughness of a heat treatment process.

5. Solid solution treatment: Solid solution treatment is the casting is heated to a suitable temperature and heat preservation, the excess phase fully dissolved, and then rapidly cooled to obtain heat treatment process of saturated solid solution. Solution the primary objective is to make carbide or other precipitates dissolved in solid solution, obtained the phase saturation.

6. Precipitation hardening treatment: Casting after solution treatment or after quenching at proper temperature, heat preservation at room temperature or above room temperature, in supersaturated segregation of solute atoms and form solid solution (or) strengthening precipitates dispersed phase and the metal hardened called precipitation hardening treatment.

7. Hydrogen removal treatment: The purpose is to remove hydrogen, improve the plasticity of cast steel. Heated to L70 and 200 degrees or 280 to 320 degrees Celsius, long time heat treatment. No histological changes. Mainly used for the low alloy steel castings is easy to produce hydrogen embrittlement tendency.