Hi Erik,

this is an interesting question! What do you exactly model ? Do you use experimental data for your stress-strain curves? You can find some data for stress-strain curves of "pure" austenite, ferrite and martensite in the SYSWELD database. If you than define your material (or better materials) from this data, the calculated residual stress will be dependent on the phase transformations and the plasticity.

Best regards,

Antoni Artinov

Hello and thanks for your reply!

I will explain a bit more what I have done.

This is from an experimental investigation where I have investigated a press-hardened component. The microstructure of the component is martensitic or autotempered martensitic with a hardness of roughly 480 HV. Certain corners of the component have an increased of 580 HV, which is a unusually high. I cannot see any plastically deformed grains but there seem to be an increased risk for brittle fracture. The corners (and the remaining geometry of the component) are believed to be plastically formed in the austenitic region.

Normally, it is assumed that the residual stresses from austenite is removed during the phase transformation to martensite, at least during simulation. This is the root of my concerns, is it viable that the residual stresses are completely removed during a displacive transformation? I would have agreed with that statement during a reconstructive transformation.

I will check on this software, I have not used this previously.

Best Regards

Erik

Speaking about residual stresses, we firstly need to define them as "positive" (tensile) and "negative" (compressive). Secondly, we should understand that since a stress is "residual", it is elastic one. A plastic stress cannot be a residual one, because it results in a plastic deformation. In the case that the yield stress of the material in higher that the stress, the last one becomes "residual".

Regarding the question, it must be noted, that usually, plastic formed austenite remains stressed. Been after plastic formic quenched, the material passes a "displasive transformation", which resulted in a formation of residual stresses of the sign opposite to that in the initial Austenite. Resulting residual stresses in the product may be measured by means of side-inclination X-rays diffraction method through measuring a representative peak shift as a function of sample tilt. Thus, if elastic properties of the analyzed material are known, a simple calculation (involving use of the measured XRD peak shift) of the residual stresses is possible.