Many metal stress-strain curves show “tiny” difference between linear approximation and real curves around yield strength. But actually it can be very large. It could produce smaller or much smaller stress when the real curves are applied in nonlinear stress analysis, comparing to linear one. The output difference is larger when product (e.g. plate) deflection is comparable to its thickness or bigger. The theoretical curves based on minimum guaranteed strength and elongation seem to be able to provide conservative design for both stress and deflection control, if they can accurately represent the real curves. Application of nonlinear analysis might have significant impact on product competitiveness. A lot more research is needed beyond this introductory report, including physical tests, to further explore the possibility and develop the methodology if possible, before any actual application for real product design can be started.