The discussion focuses on determining the proof stress of heat-treated tool steel, specifically the .2% proof stress. Participants clarify that proof stress is derived from a load-extension curve, where stress is calculated from load and cross-sectional area, and strain from extension. The challenge arises when participants cannot identify the stress/strain curve needed to find the proof stress. It is noted that if there is no curve indicating an increase in load with extension, the ultimate tensile strength (UTS) may be used instead. Overall, the conversation emphasizes the importance of understanding the relationship between load, stress, and strain in this context.
