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US 11,952,647 B2Granted
Method for manufacturing ferritic lightweight steel and ferritic lightweight steel using same
AssigneeIndustry-Academic Cooperation Foundation Gyeongsang National University
InventorsJae Bok Seol, Hyo Ju Bae, Kwang Gyu Koh, Jung Gi Kim, Hyo Kyung Sung, Young Kook Lee
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Abstract
There is provided a ferritic lightweight steel which contains 2.0 to 3.0 wt % manganese (Mn), 5.0 to 6.0 wt % aluminum (Al) and 0.1 to 0.3 wt % carbon (C) and has a tensile strength of 900 MPa to 1,108 MPa. The lightweight steel includes ferrite-austenite dual grains as a result of performing low-temperature tempering-induced partitioning (LTP) at 300° C. for 10 minutes after isothermal annealing.
Claims8
A method for producing a ferritic steel, the method comprising steps of:
- (1) subjecting an alloy to solution treatment at 1,200° C. for 90 minutes;
- (2) hot-rolling the alloy, subjected to solution treatment, at 900° C. to 1,100° C.;
- (3) air-cooling the hot-rolled alloy to room temperature at a cooling rate of 10° C./s;
- (4) cold-rolling the air-cooled alloy at room temperature until a thickness of the alloy is reduced by 70%;
- (5) subjecting the cold-rolled alloy to intercritical annealing at 850° C. to 950° C. for 90 seconds;
- (6) cooling the alloy, subjected to intercritical annealing, at a cooling rate of 10° C./s;
- (7) isothermally annealing the cooled alloy at 430° C. for 50 seconds;
- (8) air-cooling the isothermally annealed alloy;
- and
- (9) subjecting the air-cooled alloy to low-temperature tempering-induced partitioning (LTP) at 300° C. for 10 minutes,
- wherein a steel resulting from step (9) contains 2.0 to 3.0 wt % manganese (Mn), 5.0 to 6.0 wt % aluminum (Al) and 0.1 to 0.3 wt % carbon (C).
8 more elements
Dependencies are inferred from the claim text.