Tensile strength 4

[mechnano]

Is there any relation between hardness and tensile strength
If there any equation please mention.

Thanks

 

[CoryPad]

http://www.efunda.com/units/hardness/convert_hardness.cfm?HD=Approx. TS&search_string=hardness

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[NickE]

Yes, the relationship is given in ASTM E140. It is only approximate and depending on material may not be valid at all.

 

[stanweld]

Here are some additional formula from Kehl:
Plain carbon steels:
Below 175 Brinell
UT = 515 x BHN Transverse to the rollin direction
UT = 504 x BHN In direction of rolling
Above 175 Brinell
UT = 489 x BHN Transverse to the rolling direction
UT = 461 x BHN In direction of rolling

For Nickel low alloy steels:
UT = (710 x BHN) - 32,000

For chromium/nickel low alloy steels:
UT = (710 x BHN) - 33,000

For Chromium /Vanadium low alloy steels:
UT = (710 x BHN)- 29,000

FYI; I have found that the strength vs hardness of P91 alloy steel compares favorably with the last formula.

 

[EdStainless]

With a contant composition, and over limited ranges, yes there are good correlations.
Stan, You did a great job.
Once you change chemistry or the method of hardening (cold working vs heat treat) then it doesn't work.
While in general 'stronger material are harder', even small changes in chemistry change the relationship a lot.
It is even more interesting when you compare different classes of materials (steel, austenitic stainless, Ni alloy).

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[stanweld]

Ed,
I agree. All the formulae have been based on carbon and low alloy steels and they only give approximates. The relationships provided in the Metals Handbook and in ASTM E-140 are not valid for high alloy steels, austenitic stainless steels, nickel base alloys etc. I find it amazing when Engineers are able to determine whether a material meets its minimum Ultimate Tensile Strength using field hardness testing methods converted to Brinell and then using the E-140 relationships.