Normalizing is the simplest yet a very typical heat treatment process. We are making gears+shafts for two wheelrs. I faced problem with Normalizing of Gears & Shafts of Steel grade (JIS) SCM415 or SCM420. Problem is after 'Normalizing' specified Microstructure is Uniform distribution of Perlite+ferrite with bainite < 10% & hardness limits are 80-90HRB. I normalizing a load of 200kgs of SCM415 gears in an Electric Normalizing f/c (heating with electrical heater) with cycle : 870=B0C -
70minutes - forced air cooling. If I start forced air cooling just after taking the load out from the f/c it results in Hardness in the range 84-92HRB with Bainite >25% If I start forced air cooling after 3 minutes when the charge is out from f/c it resulst in very good microstructre but with hardness 76-84HRB. Ambient temp. now a days is 25-30=B0C.Any solution to this problem.
Regards
SK