Best heat treat method for 300M 3

[Steinoff]

I have made some shafts from 300M material. Before heat treating I contacted the mill and asked them for the best method of heat treat,we went over the cert papers etc and they said renormalize 1700F for 1 hour followed by air cool. Then 1600F for 1 hour ,oil quench and temper 575F for 4-6 hours and your good to go with a 53-55 Rc part. Well after this ordeal on only 1 piece I have a distorted piece of soft maple,possibly oak at 46Rc and they have no answers other than "ask your heat treater to tweek it a little" . Can anyone refer me to the correct procedure and give some insight on an alternate method which will possibly reduce distorsion.

Thanks in advance,Stein

 

[metman]

Steinoff,
Would like to corroborate the following good suggestions:
1. Hang vertical to heat and quench to minimize distortion
2. Stick with recommended austenitizing temperature.
3. Duoble temper OK and yes use lower temperature for first temper so you can check to make sure you don't draw back hardness too much and then boost the temperature on second temper if too hard.
4. It does seem that you have decarb because of an oxidixing atmosphere. It is standard practice for heat treating alloy steels to use a nuetral (not oxidizing or carburizing) endothermic or exothermic atmosphere (I don't remember which) in lieu of vacuum. A good heat treater will have the standard gases and equipment to provide this.

keep us posted.

Leonard

Jesus is THE life,
Leonard

 

[Steinoff]

Well guys you were all an incredible help. The guy who heat treats for me is really good and he had made several statements like we have discussed here but was all for any possible advice as well , he didn't want to ruin any parts.
We ended up doing a stress relief , 1575F for 1 hour after warm up standing vertical ,vertical oil quench , double temper and the results were great 51Rc to 52Rc throughout with a little decarb still happening but acceptable.
Distortion was minimal and the end result was great.
Thanks to all that offered trade secrets and such ,have a great weekend.

Thanks again,Stein

 

[TVP]

Congratulations on the success, and thanks for the update.