SEDL / STP / STP1327-EB / STP12143S

A New Corrosion Resistant, Martensitic Stainless Steel for Improved Performance in Miniature Bearings

Tomasello, CM
Senior Research Engineer, Manager - Research, and Research Engineer, Latrobe Steel Company - A Timken Company Subsidiary, Latrobe, Pennsylvania

Maloney, JL
Senior Research Engineer, Manager - Research, and Research Engineer, Latrobe Steel Company - A Timken Company Subsidiary, Latrobe, Pennsylvania

Ward, PC
Manager, MPB Corporation - A Timken Company Subsidiary, Keene, New Hampshire

Materkowski, JP
Senior Research Engineer, Manager - Research, and Research Engineer, Latrobe Steel Company - A Timken Company Subsidiary, Latrobe, Pennsylvania

Pages: 10    Published: Jan 1998

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Abstract

A new alloy, 440 N-DUR™^∗ has been developed which will provide the corrosion resistance of 440C with improved carbide size and distribution for noiseless miniature precision bearing operation. The alloy may be through hardened to achieve a minimum hardness of 60 HRC. Its nominal composition is 0.65 wt.% C, 14.5 wt.% Cr, 0.30 wt.% Si, 0.45 wt.% Mn and 0.10 wt.% N². The development of the alloy is a result of a factorial experimental design including 17 alloy variants. The optimum alloy provides a combination of the best carbide structure, corrosion resistance and heat treat response. The addition of nitrogen combined with this carbon and chromium content improves the alloy's hardenability and corrosion resistance. The alloy successfully withstands copper sulfate exposure and is currently being tested in several bearing applications. It also has great potential to outperform 440C and other corrosion resistant alloys for other ambient and low temperature applications because of its improved microstructure and heat treat response.