Max. Limit to Harden a steel

[Channo]

Hello all,

Is there any specified max. value upto which a particular steel grade could be hardened?

 

[EdStainless]

Generally you want your temper temperature to be at least 450F.
There are plenty of HT guides (like the one from Timken) that give you an idea of the hardenability of different grades of steel.
Just be cautioned that at this high hardness the toughness will be very low.
If you are looking for a balance between strength and toughness the temper temperature should be at least 1000F.

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P.E. Metallurgy, consulting work welcomed

 

[btrueblood]

Ed, in your first line did you mean temper temperature?

 

[mfgenggear]

Channo

different steel type have different requirements, there is a hand book published by ASM on heat treating of steels.
or look at the prospective steels and search on line for material data sheets for a specific product.
the design requirements will dictate the requirements of the steel used at what hardness or other metallurgical requirements.

what are you trying to design?

 

[EdStainless]

Yes, temper temperature. Ill fix it

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P.E. Metallurgy, consulting work welcomed

 

[bobjustbob]

What do you mean by specified? If you mean per a material specification then sometimes. Some specifications have max hardness values that directly limit hardness. More often the hardness is limited by the ductility requirements of the particular grade.

Is there a theoretical maximum hardness that a given grade can achieve, yes. In a standard carbon or alloy steel grade that maximum hardness would be achieved in the as quenched condition. We do not typically use steel in the as quenched condition however. In my case we use high carbon steel near the max hardness so the temper is very low. So usable hardness is about 2HRc below the as quenched hardness.

Bob

 

[Dhurjati Sen]

Entirely theoritical answer to the question, stay below the eutectic transformation temperature for steels with carbon content greater than 0.02% and those with less than 0.02% carbon, stay below the peritectic start line.

DHURJATI SEN
Kolkata, India

 

[Channo]

Thanks for all the replies.

mfgenggear
I am trying to design a steel bush with a hardness of 60-65 HRC to be used in a hydraulic cylinder.

bobjustbob
I was looking for a specification provided in some standards of ASME/ASTM.

 

[EdStainless]

First look for wire available for use in brushes.
The compare the properties.
There are only a few ASTM steel sire specs, it should be easy to look them all up and buy copies to work from.

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P.E. Metallurgy, consulting work welcomed

 

[mfgenggear]

channo

steel bush ? as a bearing or steel brush

 

[Channo]

mfgenggear
Steel bush as a bearing

 

[mfgenggear]

channo

investigated bronze bushing, and is it lubed

 

[swall]

Back to the original query--the max hardness a steel can be hardened to is entirely dependent on carbon content. The max hardness at depth below the surface is dependendent on section size, alloy content and quench media.

 

[FacEngrPE]

Hardness depends on all sorts of things, this marketing picture shows one possibility with AISI1055. "deep case hardened"

My first choice for a hydraulic cylinder bushing would not be hardened steel, as the cylinder rod is usually steel, and steel on steel bushings are usually not long life solutions.