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Fred Rowe
05-28-2011, 06:10 PM
As you raise the set temperature for tempering 01, from 500fh.=Hrc57
800fh.=HRC50 1000fh.=HRC42; what happens to the abrasion resistance as the hardness goes down?
If 01 is in the normalized state how much abrasion resistance does it possess compared to hardened 01?

I would appreciate your insight, Fred

Doug Lester
05-29-2011, 11:55 AM
This is something that gets complicated. Normalization allows the carbon to migrate out of the iron crystal as it converts from a face centered cube to a body centered cube thus allowing the formation of pearlitic steel with some of the cementite linked with alloying elements to form harder carbides than the plain cementite. It is doubtful that this would be anywhere enough to offset the loss of wear resistance from preventing martensite formation.

You could also temper at around 1000 degrees and form native carbides, but again, I would doubt that there are enough alloying elements to form native carbides to offset the reduction of hardness and accompanying wear resistance that occures from the amount of carbon disolved in the body centered crystals. It takes a higher allow steel than O1 to demonstrate secondary hardening during tempering.

Doug

Fred Rowe
05-29-2011, 03:04 PM
This is something that gets complicated. Normalization allows the carbon to migrate out of the iron crystal as it converts from a face centered cube to a body centered cube thus allowing the formation of pearlitic steel with some of the cementite linked with alloying elements to form harder carbides than the plain cementite. It is doubtful that this would be anywhere enough to offset the loss of wear resistance from preventing martensite formation.

You could also temper at around 1000 degrees and form native carbides, but again, I would doubt that there are enough alloying elements to form native carbides to offset the reduction of hardness and accompanying wear resistance that occures from the amount of carbon disolved in the body centered crystals. It takes a higher allow steel than O1 to demonstrate secondary hardening during tempering.,
Doug

Hi Doug.

I figured that the abrasion resistance would be closely related to the level of hardness and the carbides produced during the hardening process.
I am tempted to experiment with the higher tempering temperature.
At present I am tempering at 500fh which by the book is around 57hrc.
The clamp in the pic is what I am working with. I want it hard enough to withstand the abrasion as it rides along the side of the belt, but flexible enough so the clamp will not break as the bolt is tightened down. I have had maybe 15 out of 400 break. Of course the idea is to have none.;)https://lh5.googleusercontent.com/-n-tclby_iDU/TNgzTGMMlnI/AAAAAAAAA_s/UvrcINwuzG8/s512/DSC00812.JPG

Thanks for the post, Fred

Doug Lester
05-29-2011, 03:40 PM
Fred, could differential heat treating be the answere to you're problem, or at least a partial answere? Hard temper the jaws of of your clamps but draw the spring portion to a softer temper. Maybe make the clamps in three parts, the spring which is then screwed to the two jaws with the jaws extending past the sides of the spring to protect it. That might also allow you to use a higher alloy tool steel that does have a secondary hardening range for the jaws. Maybe you could even dispense with the spring part and use two set screws to tighten the clamp. Now that we see the problem you're working with some of the metallurgists will chime in.

Doug Lester

Fred Rowe
05-29-2011, 08:41 PM
Fred, could differential heat treating be the answere to you're problem, or at least a partial answere? Hard temper the jaws of of your clamps but draw the spring portion to a softer temper. Maybe make the clamps in three parts, the spring which is then screwed to the two jaws with the jaws extending past the sides of the spring to protect it. That might also allow you to use a higher alloy tool steel that does have a secondary hardening range for the jaws. Maybe you could even dispense with the spring part and use two set screws to tighten the clamp. Now that we see the problem you're working with some of the metallurgists will chime in.

Doug Lester

The whole clamp goes through two normalizing runs before its hardened. The clamps are then soaked for 30 minutes at 1475 before hardening. The first three inches of the clamp is all that goes into the oil quench; the loop of the clamp along with the adjacent 2 1/2 inches, is left normalized. I want to get the most out of the steel I'm using. I would switch to 5160H if I could get it in this size. No luck though.

Regards and thanks for your post, Fred