Nano-composite martensitic steels
AssigneeMMFX Technologies Corporation
InventorsGrzegorz J. Kusinski, David Pollack, Gareth Thomas
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Abstract
Carbon steels of high performance are disclosed that contain dislocated lath structures in which laths of martensite alternate with thin films of austenite, but in which each grain of the dislocated lath structure is limited to a single microstructure variant by orienting all austenite thin films in the same direction. This is achieved by careful control of the grain size to less than ten microns. Further improvement in the performance of the steel is achieved by processing the steel in such a way that the formation of bainite, pearlite, and interphase precipitation is avoided.
Claims12
A process for manufacturing a high-strength, corrosion-resistant tough alloy carbon steel, said process comprising:
- (a) forming a carbon steel alloy composition having a martensite start temperature of at least about 350° C.;
- (b) heating said carbon steel alloy composition to a temperature sufficient to cause said alloy composition to assume a homogeneous austenite phase with all alloying elements in solution;
- (c) treating said homogeneous austenite phase while said austenite phase is above its austenite recrystallization temperature to achieve a grain size of about 5 to 9 microns;
- and
- (d) cooling said austenite phase through said martensite transition range to convert said austenite phase to a microstructure of fused grains, each grain having a diameter of about 5 to 9 microns, and containing laths of martensite alternating with films of retained austenite in a uniform orientation throughout said grain and any carbides present in said alloy carbon steel are precipitates of less than 500 Å in diameter.
Dependencies are inferred from the claim text.