Heating rate effect Heating rate effect ckiyak (Materials) (OP) 29 Nov 17 10:21 Is there any crucial effect of heating rate in solution or aging process for precipitation hardenable alloys ? RE: Heating rate effect metengr (Materials) 29 Nov 17 15:42 Not that I have seen or reviewed. Typically, heating and cooling rates are specified to avoid formation of harmful thermal stresses that can result in locally severe distortion and/or cracking. RE: Heating rate effect MagBen (Materials) 29 Nov 17 21:56 metengr made the point. If you material is hard (>35HRC) before Heat treatment, it is recommended to pre-heat to 1000-1200F, then heat to over 1300F to prevent damage (cracking, warpage etc.). If HT machined parts, especially for those with a big cross section area change, it is always a good practice to do a preheat.