Metallic material having ultra-fine grain structure and method for its manufacture
AssigneeSumitomo Metal Industries, Ltd.
InventorsKenji Aihara, Chihiro Hayashi, Takashi Tsukamoto, Nobuhiro Murai, Hyoji Hagita
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Abstract
A method for producing a metallic material having an ultra-fine microstructure, the metallic material exhibiting a phase transformation of a low-temperature phase into a high-temperature phase is disclosed, the method comprising the steps of: preparing a metallic material which comprises at least a low-temperature phase; applying plastic deformation to the metallic material; and increasing the temperature of the metallic material to a point beyond a transformation point while applying the plastic deformation to effect reverse transformation of the low-temperature phase into a high-temperature phase.
Claims30
A method for producing a metallic material having an ultra-fine microstructure, the metallic material exhibiting a phase transformation of a low-temperature phase into a high-temperature phase, the method comprising the steps of:
- preparing a metallic material which comprises at least a low-temperature phase;
- applying plastic deformation to the metallic material;
- and
- increasing the temperature of the metallic material to a point beyond a transformation point while applying the plastic deformation to effect reverse transformation of the low-temperature phase into a high-temperature phase.
A method for producing a steel material having an ultra-fine microstructure comprising the steps of:
- preparing a steel material which comprises at least ferrite;
- applying plastic deformation to the steel with strains of 20% or more;
- increasing the temperature of the steel to a point beyond the Ac.sub.1 point while applying the plastic deformation to effect reverse transformation of at least part of the ferrite into austenite;
- and
- cooling the steel to room temperature.
A method for producing a titanium or titanium alloy material having an ultra-fine microstructure comprising the steps of:
- preparing a titanium or titanium alloy material which comprises at least .alpha.-phase;
- applying plastic deformation to the material with strains of 20% or more;
- increasing the temperature of the material to a temperature beyond the transformation point into .beta.-phase while applying the plastic deformation;
- retaining the material at the attained temperature for no longer than 100 seconds to transform at least a portion of the .alpha.-phase into .beta.-phase;
- and
- cooling the material to room temperature.
Dependencies are inferred from the claim text.