Study of Chromium-Free and Chromium-Reduced Steels

摘要

Goal was to develop an iron-based alloy, similar to Type 316 stainless steel in mechanical and corrosion properties but with a reduced Cr content or, ideally, no Cr. A total of twenty-six 225-g ingots and ten 2.5 to 12 kg ingots of various compositions in the Fe-Si-Mn-Ni-C system were prepared. All ingots contained from 5 to 11 w/o silicon and drew their corrosion resistance primarily from this component. The composition ranges of the remaining major alloying elements were (in w/o) 0-24 Mn, 0-35 Ni, and 0.08 to 0.95 C. Most of the alloys were reduced to sheet, demonstrating the hot fabricability of these high-silicon alloys. The mechanical and corrosion properties of these alloys are attractive. Tensile tests showed yield strengths of 303 to 379 Mpa (44 to 55 ksi), ultimate tensile strengths of 731 to 882 MPa (106 to 128 ksi), and elongations of 34 to 77%. Air oxidation rates were lower than those of 300-series stainless steels at 1000 exp 0 C. Salt water corrosion rates for these alloys fall between those of stainless steels and plain carbon steels and are 5 to 10 times lower than the rates for plain carbon steels. (ERA citation 08:049466)