You are dealing with a low carbon base metal that essentially will not respond to a quenching treatment, i.e., it will not harden if heated above the transition temperature and quenched. There isn't sufficient carbon to produce enough martensite to be of any consequence. That being said, I'm not advocating quenching the A36 from high temperatures, i.e., above 1400 degrees.
Heating the A36 above the transformation temperature will reduce the tensile strength, relieve any residual stress present, and restore ductility. Remember the blacksmith? The blacksmith performs most of the metal forming at temperatures on the order of 1700 to 2100 degrees with out any ill effects. Spring back is zero at the higher temperatures. Forging operation are performed in the same temperature range. Deep drawing operations which result in extensive plastic deformation require repeated annealing or normalizing operations to prevent cracking and tearing. These heat treatments restore the ductile properties of the metal before further drawing operations.
At the high temperatures, plastic deformation takes place with ease. If after working the material, it is cooled in still air, it is essentially normalized and stress free. If the material is held at these temprature for an extended time, grain coarsening can occur, but it is unlikely you will be holding it at these temperatures for the time necessary to experience grain coarsening.
The danger, as I see it, heating the base metal to a temperature that barely approaches dull cherry puts the metal in a temperature range that is in transition, i.e., transformation from BCC to FCC has started, but the temperature is too low to push the allotropic transformation to completion. There is a high probability that the metal can cool to a temperature less than 700 degrees while performing the bending operation. The concern is that the temperature is close to the blue brittle range where the steel is brittle and cracks easily.
To see what I mean, try heating a piece of the A36 to a temperature between 300 and 600 degrees and try to bend it. Don't be surprised if it fractures.
Best regards - Al