How to estimate the maximum hardenability of a steel?
How to estimate the maximum hardenability of a steel?
(OP)
I am currently working with some AISI 51B60 grade steel. Engineering has asked that we make 1/4" hex bit stock using this steel grade. The bit is to be used as part of an impact bit socket.
The internal specification requires heat treating to a hardness range of 52-55 HRC. How would I determine if this hardness range is acceptable for 51B60 steel? In other words, is it safe to harden this particular grade to this range and have it attain the required properties (impact resistance, toughness without being too brittle) as it relates to being used in an impact environment?
Would there possibly be a better steel grade to achieve this hardness range and desired properties?
The internal specification requires heat treating to a hardness range of 52-55 HRC. How would I determine if this hardness range is acceptable for 51B60 steel? In other words, is it safe to harden this particular grade to this range and have it attain the required properties (impact resistance, toughness without being too brittle) as it relates to being used in an impact environment?
Would there possibly be a better steel grade to achieve this hardness range and desired properties?





RE: How to estimate the maximum hardenability of a steel?
RE: How to estimate the maximum hardenability of a steel?
Take a look at one of the S series tool steels instead.
RE: How to estimate the maximum hardenability of a steel?
Chemical analysis will tell you the grade, and metallographic examination with show you what surface treatment was done. Rockwell hardness testing will tell you the core hardness. Your local heat treater will be able to reproduce all of that pretty easily. Total cost of testing should not exceed $500.
And no, 51B60 is not a good candidate for good toughness properties.
RE: How to estimate the maximum hardenability of a steel?
ductile. I would also recommend case hardening instead of thru hardening. The harder the steel, the more brittle it becomes. A soft core will help. You can afford to experiment with both. How do you intend to harden the steel?
RE: How to estimate the maximum hardenability of a steel?
You may have other issues to deal with if what you are making is 'part' of an impact socket.
Ted
RE: How to estimate the maximum hardenability of a steel?
As we had an impact repair shop we did make a lot of replacement parts from Bearcat (S-7).
If this item is exposed to personnel there are standards, both EU and American. At the time only the sockets were covered.
RE: How to estimate the maximum hardenability of a steel?
In theory, is there anything that could be done during heat treatment of this 51B60 material to make it better suited for impact loading?
Just out of curiosity, S tool steel doesn't specify Ni but it was suggested twice as being an element that really contributes to increased material ductility. Why would S tool steel be recommended then?
RE: How to estimate the maximum hardenability of a steel?
Ted
RE: How to estimate the maximum hardenability of a steel?
As tool steels go, S7 is on the low side of C content, and uses vanadium to promote fine grain size--both of which aid toughness.
Keep in mind that while ductility is a component of toughness they measure two different things. Also, the "hardenability" in the thread title is a measure of how thick a piece of steel will harden (transform to martensite/bainite), it does not indicate how hard the steel will be.
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