Stress-Strain Curves

Stress-strain curves are extremely valuable for comparing different steel types and even different grades within a single type of steel. Engineering stress–engineering strain curves are developed using initial gage length and initial cross-sectional area of the specimen. These curves highlight yield point elongation, ultimate tensile strength, uniform elongation, total elongation, and other strain events. In contrast, the true stress–true strain curves are based on instantaneous gage length and instantaneous cross-sectional area of the specimen. Therefore, the area under the curve up to a specific strain is proportional to the energy required to create that level of strain or the energy absorbed (crash management) when that level of strain is imparted to a part.

One of the key additions to the Advanced High-Strength Steel Application Guidelines (AHSS Guidelines) is a collection of typical stress-strain curves – both engineering and true – for different grades of HSLA, DP, TRIP, CP, MS and HF steels. The collection includes typical stress-strain curve for Mild steel in each graph for reference purposes. This will permit one to compare potential forming parameters, press loads, press energy requirements, and other parameters when switching among different steel types and grades.

You can find this important data in Section 2C of the AHSS Guidelines.  Follow the link in this article to find the AHSS Guidelines.  Also, we have attached the images for download here for your quick use.