A516 Gr.70 steel workpiece quenching and tempering

The A516 Gr.70 steel workpiece has the following characteristics after quenching:
1. Unbalanced (ie unstable) structures such as martensite, bainite, and retained austenite are obtained.
2. There is a large internal stress.
3. The mechanical properties cannot meet the requirements. Therefore, steel workpieces are generally tempered after quenching.

The effect of A516 Gr.70 steel tempering is:
1. Improve the stability of the organization, so that the workpiece no longer undergoes organizational transformation during use, so that the geometric size and performance of the workpiece remain stable.
2. Eliminate internal stress in order to improve the performance of the workpiece and stabilize the geometric size of the workpiece.
3. Adjust the mechanical properties of steel to meet the requirements of use. The quenching of steel is to heat the steel to a temperature above the critical temperature Ac3 (hypoeutectoid steel) or Ac1 (hypereutectoid steel), hold it for a period of time to make it fully or partially austenitized, and then at a rate greater than the critical cooling rate The cooling rate is quickly cooled to below Ms (or isothermal near Ms) for the heat treatment process of martensite (or bainite) transformation. Usually, the solution treatment of aluminum alloy, copper alloy, titanium alloy, tempered glass and other materials or the heat treatment process with rapid cooling process is called quenching.
 

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