As we know, residual stress will occur due to thermal causes and microstructural transformations taking place during cooling process, also the microstructure difference along the cross section for large forgings due to the hardenability limitation.
1. Here, the steel is heated to a Temperature below A1 without phase transformation, then quenched in water, only thermal stress is considered. Is it possible to eliminate the thermal stress by low temperature tempering (200-300C)?
2. There are some high strength industrial steels such as 300M, or other high Si addition bainitic steels. The heat treatment process should be usually the quenching+low temperature tempering for large cross section forgings. It is reported those alloys could obtain high mechanical properties. So, how should we consider the residual stress, especially the core area in the forgings. Usually, a high temperature tempering (500~600) process is needed if we want to relief most of the residual stresses.
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