Is it possible to use a Charpy V-nottch Impact value to de-rate yield stress of material @low temp?

[blue1074]

We have a Material Testing Report for a few parts that were manufactured that give 3 impact values at 20 degrees Celsius and 1 impact value at -20 degrees Fahrenheit. All values are longitudinal and transverse values are not given.

The material is a CroMolloy Steel (P110 tubular 4130 steel) with yield and tensile of 135 and 150 ksi respectively.

Is there any way to correlate impact values to yield strengths? We use SolidWorks simulation/FEA to verify Factor of Safety our designs, but because some of our products are used in extreme temperature (-20 degrees Celsius) environments, we would like to make sure we are using the "correct"/conservative yield strength value for our materials. Everything I can find in the literature about impact energy values always points back to crack propagation mechanics/theory which is not something we investigate or verify using SolidWorks.

One thought I had was if there was some way to use the traditionally qualitative property of impact value to correspond to a de-rated yield strength by means of a publication or equation I haven't been able to find yet, we could add an additional layer of safety to our designs.

In summary, I am looking for a way to use a longtiudinal or transverse impact value to accurately de-rate yield stress of materials.

 

[btrueblood]

No. In fact, for typical HSLA steel, the yield strength increases at low temperatures. The charpy test is showing that the ductility (post-yield behavior) of the steel is diminishing, completely different mechanics than yield strength.

 

[Metalero]

You need to have to include the microstructural condition, as well as the grain size of the material, to compare it with some empirical relationships. I do not have a specific for 4130, but many of HSLA, which have similar resistances and behavior, are in the PAPER.