Method for improving hydrogen-induced delayed fracture resistance of Fe-Mn-Al-C light steel
Technical Field
The invention relates to the technical field of light steel, in particular to a method for improving the hydrogen-induced delayed fracture resistance of Fe-Mn-Al-C light steel.
Background
With the global energy crisis and the worsening of the environment, the energy consumption and pollution problems of automobiles are concerned by researchers as vehicles which are most widely applied and frequently used all over the world. The automobile industry becomes an important economic component in China, and the energy conservation and emission reduction of automobiles are also one of important measures for environmental protection in China.
The development direction of the automobile industry in the future is light weight, high reinforcement, high safety and greening. The future steel for the automobile must have high strength, high toughness and plasticity, good weldability, formability, collision energy absorption, good fatigue performance, corrosion resistance, dent resistance and the like, and the steel for the automobile has high cost performance on the premise of meeting performance requirements, and also has low energy consumption production and recovery of materials and parts, so that a green supply chain system of the whole life cycle is realized.
At present, Fe-Mn-Al-C light steel draws wide attention in the automobile industry by virtue of the advantages of high strength, high toughness, high elongation, low density, good corrosion resistance, good formability, creep resistance, strong impact resistance, high safety index and the like, and becomes a new generation of automobile steel with strong development potential.
Meanwhile, compared with the traditional high-strength steel, the weight reduction effect of the Fe-Al-Mn-C series light steel is more obvious, and the Fe-Al-Mn-C series light steel has obvious advantages as future automobile steel.
Although Fe-Mn-Al-C light steel becomes a new generation of automobile steel with strong development potential by virtue of unique advantages, the development still faces some key scientific problems: delayed fracture of high strength lightweight steel. The high strength is a necessary trend of the development of automobile steel, and also brings new challenges to the automobile steel, when the tensile strength exceeds 1000MPa, the phenomenon of delayed fracture caused by hydrogen is easy to occur, and the higher the strength is, the more serious the hydrogen embrittlement sensitivity is; the delayed fracture caused by hydrogen brings serious potential safety hazard to automobiles and passengers, and causes great economic and reputation loss to automobile factories. How to improve the problem of hydrogen-induced delayed fracture of the light steel is a key technical bottleneck for developing the high-strength automotive light steel.
Therefore, we have proposed a method for improving the hydrogen-induced delayed fracture resistance of Fe-Mn-Al-C lightweight steel to solve the above-mentioned problems.
Disclosure of Invention
The invention aims to solve the defects in the prior art and provides a method for improving the hydrogen-induced delayed fracture resistance of Fe-Mn-Al-C light steel.
The method for improving the hydrogen-induced delayed fracture resistance of the Fe-Mn-Al-C light steel comprises the following steps:
s1, weighing the raw materials according to a preset proportion, wherein the high-strength Fe-Mn-Al-C lightweight steel comprises the following chemical components in percentage by weight:
c: 0.9 to 1.2%, Al: 9.0-11.0%, Mn: 26.0-31.0%, Cu: 1.0-5.0%, and the balance of Fe and impurities;
s2, putting the raw materials into a vacuum medium-frequency induction furnace for smelting, casting into an ingot, and then cooling to room temperature;
s3, forging the cooled cast ingot, heating to 1000-1100 ℃ before forging, preserving heat for 1-2 hours, keeping the forging temperature at 950-1000 ℃, and air-cooling to room temperature after forging to obtain a forged piece;
s4, hot rolling the forged piece, heating to 1000-1100 ℃ before hot rolling, keeping the temperature for 0.5-1.5 hours, and then obtaining a hot rolled piece after hot rolling;
s5, cold rolling the hot rolled piece in the S4, heating to 900-1000 ℃ before cold rolling, and preserving heat for 1-2 hours to obtain a cold rolled piece;
and S6, carrying out aging treatment on the cold-rolled piece in the S5, wherein the aging treatment temperature is 450-650 ℃, the treatment time is 1-24 h, and cooling to room temperature after the aging treatment is finished.
Preferably, in the step S4, the start rolling temperature during hot rolling is 900 to 1100 ℃, and the finish rolling temperature is 800 to 900 ℃.
Preferably, in the step S4, the reduction ratio is 20% for each time in the hot rolling process, and the rolling is performed for 8 to 10 passes.
Preferably, in the step S5, the reduction ratio is 5% in each cold rolling process, and the rolling is performed for 12 to 14 passes.
Preferably, in the step S6, the cooling method after the aging treatment is any one of air cooling, furnace cooling, and water cooling.
Preferably, the impurities are Si, P and S, and the mass percentages of the impurities are respectively Si: less than or equal to 0.1 percent, P less than or equal to 0.03 percent, S: less than or equal to 0.005 percent.
Compared with the prior art, the invention has the beneficial effects that:
1. the added Cu element is low in price, and the hydrogen-induced delayed fracture resistance of the steel can be improved with small investment.
2. A proper amount of Cu element is added into Fe-Mn-Al-C light steel, and after the steel is sequentially subjected to smelting, forging, hot rolling, cold rolling and aging treatment, precipitated nano Cu-rich particles can promote the precipitation of kappa-carbide, so that the number of irreversible hydrogen traps in the steel is increased, and the aim of improving the hydrogen-induced delayed fracture resistance of the light steel is fulfilled.
3. A proper amount of Cu element is added into the Fe-Mn-Al-C light steel, and the co-precipitation of nano Cu-rich particles and kappa-carbide can be realized by regulating and controlling reasonable aging treatment temperature and aging treatment time, so that the number of irreversible hydrogen traps in the steel is increased, and the aim of improving the hydrogen-induced delayed fracture resistance of the light steel is fulfilled.
4. A proper amount of Cu element is added into Fe-Mn-Al-C light steel, and the precipitation size of nano Cu-rich particles and kappa-carbide and the appearance of the kappa-carbide can be changed by regulating and controlling the aging treatment temperature and the aging treatment time, so that the hydrogen trap binding energy of the kappa-carbide in the steel is changed, and the aim of changing the hydrogen-induced delayed fracture resistance of the light steel can be fulfilled.
Detailed Description
The present invention will be further illustrated with reference to the following specific examples.
The method for improving the hydrogen-induced delayed fracture resistance of the Fe-Mn-Al-C light steel comprises the following steps:
s1, weighing the raw materials according to a preset proportion, wherein the high-strength Fe-Mn-Al-C lightweight steel comprises the following chemical components in percentage by weight:
c: 0.9-1.2%, Al: 9.0-11.0%, Mn: 26.0-31.0%, Cu: 1.0-5.0 percent of Fe and impurities (the impurities are less than or equal to 0.1 percent of Si, less than or equal to 0.03 percent of P and less than or equal to 0.005 percent of S);
s2, putting the raw materials into a vacuum medium-frequency induction furnace for smelting, casting into an ingot, and then cooling to room temperature;
s3, forging the cooled cast ingot, heating to 1000-1100 ℃ before forging, preserving heat for 1-2 hours, keeping the forging temperature at 950-1000 ℃, and air-cooling to room temperature after forging to obtain a forged piece;
s4, hot rolling the forged piece, heating to 1000-1100 ℃ before hot rolling, preserving heat for 0.5-1.5 hours, then obtaining a hot rolled piece after hot rolling, wherein the initial rolling temperature is 900-1100 ℃, the final rolling temperature is 800-900 ℃, and in the hot rolling process, the reduction rate of each time is 20%, and the rolling is carried out for 8-10 times;
s5, cold rolling the hot rolled piece in the S4, heating to 900-1000 ℃ before cold rolling, and preserving heat for 1-2 hours to obtain a cold rolled piece, wherein the reduction rate of each time is 5% in the cold rolling process, and the cold rolled piece is rolled for 12-14 times;
and S6, performing aging treatment on the cold-rolled piece in the S5, wherein the aging treatment temperature is 450-650 ℃, the treatment time is 1-24 h, the cold room temperature is cooled after the aging treatment is finished, and the cooling mode after the aging treatment is any one of air cooling, furnace cooling and water cooling.
Example 1:
c: 0.9%, Al: 9.0%, Mn: 26.0%, Cu: 1.0 percent of Fe and inevitable impurities (wherein, Si is less than or equal to 0.1 percent, P is less than or equal to 0.03 percent, and S is less than or equal to 0.005 percent).
Weighing the raw materials according to a preset proportion, then putting the raw materials into a vacuum intermediate frequency induction furnace for smelting, casting the raw materials into an ingot, and cooling the ingot to room temperature; forging treatment: heating to 1050 ℃ before forging, preserving heat for 1.5h, forging at 950 ℃, and cooling to room temperature after forging; hot rolling treatment: heating to 1050 ℃ before hot rolling, preserving heat for 1h, rolling at the beginning temperature of 1000 ℃, rolling at the finishing temperature of 850 ℃, rolling at the reduction rate of 20% for each time, and rolling for 9 times; cold rolling treatment: heating to 950 ℃ before cold rolling, preserving heat for 1h, wherein the reduction rate is 5% each time, and rolling for 13 times; the aging treatment temperature is 450 ℃, the aging time is 3 hours, and the water is cooled to the room temperature.
Example 2:
c: 1.0%, Al: 10.0%, Mn: 28.0%, Cu: 3.0 percent of Fe and inevitable impurities (wherein, Si is less than or equal to 0.1 percent, P is less than or equal to 0.03 percent, and S is less than or equal to 0.005 percent). Weighing the raw materials according to a preset proportion, then putting the raw materials into a vacuum intermediate frequency induction furnace for smelting, casting the raw materials into an ingot, and cooling the ingot to room temperature; forging treatment: heating to 1050 ℃ before forging, preserving heat for 1.5h, forging at 950 ℃, and cooling to room temperature after forging; hot rolling treatment: heating to 1050 ℃ before hot rolling, preserving heat for 1h, rolling at the beginning temperature of 1000 ℃, rolling at the finishing temperature of 850 ℃, rolling at the reduction rate of 20% each time for 9 times; cold rolling treatment: heating to 950 ℃ before cold rolling, preserving heat for 1h, wherein the reduction rate is 5% each time, and rolling for 13 times; the aging treatment temperature is 550 ℃, the aging time is 3 hours, and the air cooling is carried out until the room temperature.
Example 3:
c: 1.2%, Al: 11.0%, Mn: 31.0%, Cu: 5.0 percent of Fe and inevitable impurities (wherein, Si is less than or equal to 0.1 percent, P is less than or equal to 0.03 percent, and S is less than or equal to 0.005 percent). Weighing the raw materials according to a preset proportion, then putting the raw materials into a vacuum intermediate frequency induction furnace for smelting, casting the raw materials into an ingot, and cooling the ingot to room temperature; forging treatment: heating to 1050 ℃ before forging, preserving heat for 1.5h, forging at 950 ℃, and cooling to room temperature after forging; hot rolling treatment: heating to 1050 ℃ before hot rolling, preserving heat for 1h, rolling at the beginning temperature of 1000 ℃, rolling at the finishing temperature of 850 ℃, rolling at the reduction rate of 20% each time for 9 times; cold rolling treatment: heating to 950 ℃ before cold rolling, preserving heat for 1h, wherein the reduction rate is 5% each time, and rolling for 13 times; the aging treatment temperature is 620 ℃, the aging time is 10 hours, and the temperature is cooled to room temperature along with the furnace.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.