Problem with bearing structure
Problem with bearing structure
(OP)
A bearing is sold to a customer and works good for 1-2 weeks, then it breaks.
When it came back, he has a different structure than it should have. A good structure is quenched(martensite) and it came back with an annealing structure(speroidised, fine globular cementite).
I want to know what would be the different causes of this(how did it happen).
When it came back, he has a different structure than it should have. A good structure is quenched(martensite) and it came back with an annealing structure(speroidised, fine globular cementite).
I want to know what would be the different causes of this(how did it happen).





RE: Problem with bearing structure
Aaron Tanzer
www.lehightesting.com
RE: Problem with bearing structure
RE: Problem with bearing structure
RE: Problem with bearing structure
RE: Problem with bearing structure
Aaron Tanzer
www.lehightesting.com
RE: Problem with bearing structure
What kind of wear do you see?
RE: Problem with bearing structure
RE: Problem with bearing structure
RE: Problem with bearing structure
I work in the metallographic laboratory so I must know also how they fail and how to resolve problems that arise.
Thanks anyway for your response.
RE: Problem with bearing structure
Next bearings you supply, keep a control sample in your desk until such time as this customer returns a destroyed unit. Better yet, do some random sampling for hardness testing and metallography, a.k.a. QC.
RE: Problem with bearing structure
RE: Problem with bearing structure
From your limited description of the observed microstructure, I wonder if what you are seeing is a microstructure resulting from either too low of an austenitizing temperature or excessively high tempering temperature. While a metallogropher may not be the best failure analysist, a good metallographer should be able to recognize what thermo-mechanical history is needed to produce a given microstructure, given the steel chemistry and standard processing. There is a lot you can learn from from the microstructure, you should try to find out more from the manufacturing side what could have happened during processing as well as from the customer support side as far as what the application was. Correlate these with the clues seen in the microstructre and you will have a better understanding of what has happened.
rp
RE: Problem with bearing structure
RE: Problem with bearing structure
Design for RELIABILITY, manufacturability, and maintainability
RE: Problem with bearing structure
The half with annealed structure has 25-30 HRC, the other half has 40-45 HRC.
Here is the etched sample.
Annealed structure
Normalized structure
RE: Problem with bearing structure
RE: Problem with bearing structure
Annealed structure http://img109.imageshack.us/img109/4097/dscn5277h....
Normalized structure http://img803.imageshack.us/img803/6963/dscn5280co...
RE: Problem with bearing structure
RE: Problem with bearing structure
With the photomicrographs, it would help if you would identify the magnificaiton. I am also guessing, what you are calling "annealed structure" is taken from the right side of the "etched sample" and the "normalized structure" is from the right? The hardness of these two regions would also be enlightening.
What is the chemical composition of the steel? 52100 has been suggested, but my guess is that is only based that that is a common grade used in beraings. Do you know what the grade of steel is? Also, what is the overall size of the bearing? Is the bearing produced from bar stock? a forging? Do you know the perscribed heat treatment?
The left side of the "etched sample" appears to have multiple zones, much like what you would see with weld repair. As 52100 is not readialbe weldable, this does not make much sense, but that is the impression I get from looking at it.
We really need more information to provide much insight.
rp
RE: Problem with bearing structure
rp
RE: Problem with bearing structure
Magnification of microscope pictures is x500 .
My guess is that it didn't go to the second heat treatment.
The half with annealed structure has 25-30 HRC, the other half(normalized) has 40-45 HRC.
The size of the bearing is 150 mm i think. The ring is forged, rolled, annealed and after this he must be quenched and tempered for hardening.
I put again the pictures for dbooker630.
sample Link
annealed Link
normalized Link
RE: Problem with bearing structure
RE: Problem with bearing structure
So i guess the second heat treatment was not done.
But what did happen to the ring that it has a half annealed structure and a half normalized?
It is possible that the ring was annealed and by working it reached high temperatures and normalized?
RE: Problem with bearing structure
rp
RE: Problem with bearing structure
There is nothing we have seen at this point to suggest this bearing ever received a proper heat treatment, but as redpicker suggests, one side of the improperly heat treated bearing may have been heated for installation.
If in fact this part missed quench and temper you will need to review your lot traceability procedures, process flows, and control plans (if you have them). Something is wrong with material flow if green parts get to the customer.
RE: Problem with bearing structure
http://files.engineering.com/getfile.aspx?folder=8...
http://files.engineering.com/getfile.aspx?folder=8...
http://files.engineering.com/getfile.aspx?folder=c...
http://files.engineering.com/getfile.aspx?folder=f...
http://files.engineering.com/getfile.aspx?folder=a...
My colleague that has 25+ years of experience in metallurgy said that this ring was properly heat treated, but for some reason(maybe in service), it overheated, thus the annealed and normalized structure. Maybe it did behave like it was annealed in furnace, this is what I have to believe.
RE: Problem with bearing structure
RE: Problem with bearing structure
And some FAILURE ANALYSTS in metallography labs should never have gotten in the business. Too many engineering overlords assume that because an appointed underling one has a degree or a PE they can excel at this kind of masochistic reverse engineering. Even within the field of 'metallurgical failure analysis' I find myself working within a surprisingly narrow range of industries.
"If you don't have time to do the job right the first time, when are you going to find time to repair it?"