Let's discuss your claim that the stainless steel in the chart I posted is a "low strength steel." That claim is BOGUS!
Although the 17-4 Stainless Steel on the chart is tested as a casting and its hardness at 120ksi is therefore lower than rolled or extruded form at 140-160ksi, the rating of this stainless steel makes it among the strongest of the stainless steels. In fact it is a "Precipitation-hardening martensitic stainless steel, which have corrosion resistance comparable to austenitic varieties, but can be precipitation hardened to even higher strengths than the other martensitic grades."
17-4PH, uses about 17% chromium and 4% nickel. There is a rising trend in defense budgets to opt for ultra-high-strength stainless steel such as 17-4PH when possible in new projects. So much for your claim of "allow strength steel!" The Defense Department's contracts are still in place and research and development is taking place on new weaponry using casting of liquid metal as we debate, much to your chagrin.
On the flip side, that chart on the elasticity of this material couldn't be much more confusing. This is not a measure of ductility, but in fact a measure of "springiness" the amount of deformation the material can take without deforming.
A plain carbon steel will provide 25% elongation to rupture, where as hi-tensile, high carbon steels (like rebar) can only achieve 10% elongation to rupture. This is the trade off. But it is hard for me to imagine that only .5 percent of this strain is below the yield strength, so I am scratching my head too. On the surface this chart would seem to imply that all of these metals are fairly brittle, and I just don't get that. Maybe I got up on the wrong side of the bed.