Hardness and Mechanical Properties

[ScottishMet]

A quenched and tempered low alloy steel with a minimum hardness specification of 341-BHN would be generally expected to achieve a yield strength of 130,000-psi and an ultimate tensile strength of 160,000-psi.
What percentage of samples tested could fall below the expected yield and ulimate values?

 

[redpicker]

There are too many variables to give any significant answer. How large is the section? For example, is this a 6 inch diameter bar with 341 on the surface, but tensile tests are performed at mid-radius? If that is the case, depending on the alloy content and heat treating specifics, anywhere from 0% to 100% could fail to meet these requirements.

However, I'd expect nearly 100% compliance if the hardness met both on the surface and at mid-radius, at least on the yield. I wouldn't be surprised to see some ultimate tensile strengths in the 155-160 KSI range at 341 HBW.

rp