SAE 1045 axle shafts bend after induction hardening 1

[thejackal3]

Lately we have seen that many axle shafts (SAE 1045) are bending more than often after induction hardening and also while doing straightening process after tempering to 50 -55 hrc still axle shafts are breaking from center.some axle shafts are through hard which we check and suspect. This could be the reason that these are breaking.? please required expert advice on this.

 

[swall]

Yes, through hardening would make the shafts susceptible to breakage during straightening. If you look at the fracture surface, you will be able to differentiate between case and core and tell if your case depth is excessive. You need to fix the hardening problem first, then work on the straightness issue.

 

[dbooker630]

You may want to check the incoming material - chemistry, DI, reduction ratio. Any changes in these characteristics can affect straightness and response to induction hardening. Confirm that you have 1045 and not a modified or 1541 grade.

As far as the hardening itself, check your power level, frequency, and scan speeds for fluctuation. Your quenchant supplier should be able to check your polymer concentration and cleanliness for you.

 

[thejackal3]

thanks for the valuable advise Mr.swall and dbooker ,we have corrected the issues in the hardening process.out of that lot which is more bend than usual how can we make those axles in use.My straightening person is not willing to straighten them as he is afraid that axles will break.any other option apart from straightening them as soon as they come out from tempering furnace.can puting those axles in tempering for more time can help in decreasing the case depth and bendness of them.if yes than for how much time and at how much temperature we make them temper.
thanks n regards

 

[dbooker630]

I can understand the operator's concern, especially if there are no protective barriers. Straightening in the warm condition helps but there are safety concerns here also.

I don't know your hardness and case depth specs so it is difficult to comment on adding time and/or temperature to the temper cycle. You may also need to validate this since it is a change to your control plan.

If your procedures allow rework, try normalizing the shafts or temper at 800F, then straighten in this condition. Repeat the induction harden process, if the issues have been fixed runout should be reduced.

 

[thejackal3]

sir quench hardness is about 60 hrc and case depth is more 8 mm on 34 mm dia axle shaft.its possible to normalize the finish axle shafts again.there wont be a problem of scaling if we normalize again.