Method for fabricating vehicle components and new use of a precipitation hardenable martensitic stainless steel
AssigneeSandvik AB
InventorsAnna-Lena Nyström, Anna Hultin Stigenberg
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Abstract
A composition and method for the manufacture of products of a precipitation hardenable martensitic stainless steel, the composition of which comprises at least 0.5% by weight of Cr and at least 0.5% by weight of Mo wherein the sum of Cr, Ni and Fe exceeds 50%. The method steps include smelting the material into a casting, hot extrusion followed by a number of cold deforming steps so as to obtain at least 50% martensite and finally an ageing treatment at 425-525° C. to obtain precipitation of quasicrystalline particles. Such material can be used in vehicle components where demands for corrosion resistance, high strength and good toughness are to be satisfied.
Claims11
An automotive component having corrosion resistance, high strength and toughness, the automotive component formed as a tubular member having a composition comprising at least 0.5% by weight chromium, at least 0.5% by weight molybdenum, and the sum of Cr, Ni and Fe exceeds 50% by weight;
- the automotive component having a microstructure comprising at least 70% martensite with quasicrystalline particles of intermetallic compounds dispersed in the martensite.
A method of manufacturing comprising:
- smelting an alloy having a composition comprising at least 0.5% by weight chromium, at least 0.5% by weight molybdenum, and the sum of Cr, Ni and Fe exceeds 50% by weight;
- casting the alloy;
- subjecting the casting to hot extrusion and then to a plurality of cold rolling steps;
- thereafter cold deforming the alloy to obtain of at least 50% martensite throughout its microstructure;
- and
- subjecting the alloy to an ageing treatment at 425-525° C. that is sufficient to obtain precipitation of quasicrystalline particles in the martensitic microstrucure,
- wherein the total amount of deformation occurs without an intermediate annealing step between each and every deformation step.
Dependencies are inferred from the claim text.