×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Induction hardening distortion
6

Induction hardening distortion

Induction hardening distortion

(OP)
Hello,
We have had some trouble with one of our spindle shafts.
1. I was hoping to learn how to estimate how much distortion/ dimensional growth I should expect after induction hardening a shaft (drawing attached). Material is 4140. Could someone provide a number, or means to calculate?
2. I would like to improve our drawing callout for heat treat. All we say now is induction harden, min. 45 HRc, and the location to be hardened. Could someone provide pointers, or reference material for specifying?

Thanks,
Mark

RE: Induction hardening distortion

Hello Mark,

 Distortion will be tough to create a specific formula, since there are many factors that contribute... processing history, heat-up rate, quench rate...

As far as you call-out - you need to add a minimum temper say 300- 350F just to make sure you don't have a surface of virgin martensite. Most heat treaters will do this automatically.... but it is better to be safe-than-sorry. Other consideration...if you are concerned with distortion you may want to mandate an oil quench (or even warm oil).

RE: Induction hardening distortion

2
As has been mentioned above, there are too many variables that contribute to the distortion to be able to accurately predict how much you will get (or even if it will be a growth or a shrinkage).  The best you can do is be aware that distoriton will occur and either adjust your tolerances to allow for it or plan on finishing after heat treatment.

I don't like the practice of specifying the tempering temperature in this case.  The problem with specifiying a tempering temperature is if there is a problem, at least part of the blame could be put on the tempering temperature that was specified.  If you tell the baker how to make the cake, you can't complain about how it tastes.

Rather than specify a minimum temper, I would suggest you change the callout from just "induction harden" to "induction harden and temper", and then give a hardness range instead of just a minimum.  That is, your note could say, Induction harden and temper to 45-50 HRC.  Personally, I think 50 HRC is a bit high for 4140, but if you have too narrow of a hardness range, the heat treater will not be able to hit it.  If you could accpet 42 HRC as a minimum, I'd be more comfortable with 42-47 HRC than 45-50.  If you just have to maintain the 45 HRC minimum, I'd suggest a talk with your heat treater to see how narrow of a range he would be comfortable with.

rp
 

RE: Induction hardening distortion

2
To my experience this part should be heat treated all over before (final) machining/grinding. It will be cheaper and you will save the induction treatment and distortion.   

RE: Induction hardening distortion

MarkQA,

I'd agree with israelkk's comments.  If all you need in that flange area is Rc45, rough machining and then a full oil quench and 800degF temper, followed by finish machine operations on the part would be more cost effective.

An induction heating and quenching of the flange area would leave you with a very hard and brittle material condition (>Rc55) unless it was subsequently tempered.  Quenching the flange area with those small holes and sharp edges may also result in cracking.

Good luck.
riff_raff

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources