Rapid tempering can get basically the same microstructure as traditional tempering, and the rapid tempering time is prolonged, and the carbides of A36 steel gather and grow. When the rapid tempering holding time is extended from 40s to 120s, the impact value decreases; the microhardness is the highest when the tempering holding time is 40s. The best process for rapid tempering is holding at 620°C for 40s. It may be considered to implement Jihuo-rapid tempering process on A36 steel.
Tempering transformation is a structure transformation controlled by diffusion, and the organization transformation depends not only on temperature, but also on time, but temperature is the main one. For example, the decomposition of retained austenite in A36 steel should be above 200°C, the precipitation of FesC should be above 200°C, and the recrystallization of ferrite should be above 600°C, etc., all of which indicate that temperature is the decisive factor in the process of microstructure transformation.
However, the tempering transformation of A36 steel can occur within a certain temperature range, and within this range, the transformation occurring at a lower temperature for a longer time and higher temperature for a shorter time may have the same effect.
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