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CN-116732418-B - Tempered-brittleness-free alloy structural steel and preparation method thereof

CN116732418BCN 116732418 BCN116732418 BCN 116732418BCN-116732418-B

Abstract

The application provides a tempering-free brittle alloy structural steel and a preparation method thereof. The preparation method comprises the technological processes of blast furnace molten iron smelting, desulfurization, converter smelting, LF refining, RH degassing, continuous casting, slab heating, rough rolling, finish rolling, coiling, air cooling, leveling, heating, quenching and tempering, wherein in the continuous casting process, the ladle molten steel comprises the following components ：C：0.03％～0.75％;S≤0.0004％;Ca：0.0006％～0.0016％;P≤0.0040％;Sb≤0.0005％;Sn≤0.0030％;As≤0.0015％;Pb≤0.0005％;N：0.0030％～0.0050％;Ti：0.0108％～0.0200％;H≤0.00015％;Als：0.04％～0.06％; in percentage by mass, wherein the mass percentage relation of the components satisfies that Ca/S is more than or equal to 2, ti/N=3.6-5.0, si+Mn+Cr+Ni+Mo+V+Nb=0.5-12.0%. According to the preparation method of the alloy structural steel without tempering brittleness, provided by the application, the first type tempering brittleness and the second type tempering brittleness of the alloy structural steel are avoided by adjusting the chemical components and the content of the chemical components in the steel plate, so that the problem that the quenched steel plate of the alloy structural steel is embrittled in the tempering brittleness temperature range during service is solved.

Inventors

  • Wu Kangmian
  • LI CHUNHUI
  • WANG JING
  • LIU PENG
  • QI JIANGHUA
  • DENG ZHIXUN

Assignees

  • 湖南华菱涟源钢铁有限公司

Dates

Publication Date
20260505
Application Date
20230529

Claims (9)

  1. 1. The preparation method of the non-tempering brittle alloy structural steel is characterized by comprising the process flows of blast furnace molten iron smelting, desulfurization, converter smelting, LF refining, RH degassing, continuous casting, slab heating, rough rolling, finish rolling, coiling, air cooling, flattening, heating, quenching and tempering; In the continuous casting process, the ladle molten steel comprises components ：C：0.03%~0.75%;S≤0.0004%; Ca：0.0006%~0.0016%; P≤0.0040%;Sb≤0.0005%;Sn≤0.0030%;As≤0.0015%;Pb≤0.0005%;N：0.0030%~0.0050%;Ti：0.0108%~0.0200%;H≤0.00015%;Si≤0.70%;Als：0.04%~0.06%; in percentage by mass, wherein the percentage by mass of the components is more than or equal to 2 percent of Ca/S, 3.6-5.0 percent of Ti/N=Si+Mn+Cr+Ni+Mo+V+Nb=0.5-12.0 percent, and the balance of Fe and other unavoidable residual elements or impurity elements in smelting.
  2. 2. The method for preparing the alloy structural steel according to claim 1, wherein in the continuous casting-slab process, the mass percentage relation of Ca and S in molten steel in a tundish is as follows, ca/S=2-4, S is less than or equal to 0.0004%, and Ca is 0.0006% -0.0016%.
  3. 3. The method for producing an alloy structural steel according to claim 1, wherein in the blast furnace molten iron smelting process, sn is 0.0020% or less, as is 0.0010% or less, and P is 0.10% or less.
  4. 4. The method for producing alloy structural steel according to claim 1, wherein after the desulfurization process, the content of S in the molten iron satisfies s≤0.0005%.
  5. 5. The method for producing an alloy structural steel according to claim 1, wherein the content of S in the molten steel after the LF refining process satisfies s≤0.0002%.
  6. 6. The method for preparing alloy structural steel according to claim 1, wherein in the converter smelting process, double slag smelting is adopted and iron oxide scale is added, and the end point P mass percent is less than or equal to 0.0030%.
  7. 7. The method for preparing the alloy structural steel according to claim 1, wherein after the RH degassing technology, the ladle molten steel in continuous casting is prepared from the following components, by mass, 0.0030% -0.0050% of N, 0.0120% -0.0200% of Ti, less than or equal to 0.00015% of H, less than or equal to 0.0004% of S, and 0.0006% -0.0016% of Ca, wherein the mass percentage of the components is more than or equal to 2.
  8. 8. The tempering-free brittle alloy structural steel is characterized by comprising the following components in percentage by mass: C：0.03%~0.75%;S≤0.0004%; Ca：0.0006%~0.0016%; P≤0.0040%;Sb≤0.0005%;Sn≤0.0030%;As≤0.0015%;Pb≤0.0005%;N：0.0030%~0.0050%; Ti：0.0108%~0.0200%;H≤0.00015%;Si≤0.70%;Als：0.04%~0.06%; The mass percentage content of the components is more than or equal to 2 percent of Ca/S, ti/N=3.6-5.0 percent, si+Mn+Cr+Ni+Mo+V+Nb=0.5-12.0 percent, and the balance of Fe and other unavoidable residual elements or impurity elements in smelting.
  9. 9. The temper-free brittle alloy structural steel according to claim 8, wherein the temper-free brittle alloy structural steel has a tensile strength of 975 mpa-805 mpa, a yield strength of 930 mpa-7515 mpa, an elongation of 27% -38%, and an impact energy of-60 ℃ of 198j-254 j.

Description

Tempered-brittleness-free alloy structural steel and preparation method thereof Technical Field The application relates to the technical field of steel preparation, in particular to a tempering-brittleness-free alloy structural steel and a preparation method thereof. Background The phenomenon that the quenched martensite of steel decreases in impact toughness with an increase in tempering temperature is called tempering brittleness of steel. The temper brittleness of steel is classified into a first type of temper brittleness and a second type of temper brittleness. The carbon structural steel is tempered at a temperature range of 200-400 ℃ after quenching, and low grains appear in impact toughness, which is called first-class tempering brittleness and also called low-temperature tempering brittleness. In alloy steels, the first type of temper embrittlement occurs at a temperature slightly higher than that of carbon steel, typically between 250-450 ℃. The first type of temper brittleness is irreversible, i.e. the temper brittleness cannot be eliminated after the occurrence of the temper brittleness, i.e. the tempering at a temperature range of non-temper brittleness (e.g. 150-180 ℃) and the tempering at a temperature range of non-temper brittleness after the re-heating quenching is needed. The second type of temper brittleness, also called high temperature temper brittleness of quenched martensite, is above the first type of temper brittleness temperature, and can be eliminated by only tempering at a temperature higher than the temper brittleness temperature and rapidly cooling after tempering, so that the type of temper brittleness is also called reversible temper brittleness. The alloy structural steel which is quenched and tempered at low temperature in the first tempering brittleness temperature range still has first tempering brittleness when being insulated in the first tempering brittleness temperature range, and still has second tempering brittleness when being insulated in the second tempering brittleness temperature range. This means that the heat treated high strength steel subjected to the quenching and low temperature tempering treatment will still be embrittled by the first or second type of temper embrittlement if it is in service in the temperature range where the temper embrittlement occurs. In recent years, high temperature resistant NM400, NM450, NM500 have been under development due to the push of market demand. The service temperature of the high-temperature wear-resistant steel plate is generally required to be in the range of 200-500 ℃, and the service temperature is in the range of the tempering brittleness of the first class and the second class, so that the development of the high-temperature wear-resistant steel plate aims to solve the tempering brittleness problem of the steel, and the heat strength is improved by adding Mo, V and other elements on the basis of common NM400, NM450 and NM500 components, and the oxidation resistance is improved by adding Cr and other elements. Disclosure of Invention Aiming at the technical problems, the embodiment of the application provides a structural alloy steel without tempering brittleness and a preparation method thereof, and aims to provide heat treatment high-strength alloy structural steel without tempering brittleness of a first type and tempering brittleness of a second type, improve the production efficiency and widen the application range. In a first aspect, the embodiment of the application provides a preparation method of a tempering-free brittle alloy structural steel, which comprises the process flows of blast furnace molten iron smelting, desulfurization, converter smelting, LF refining, RH degassing, continuous casting, slab-slab heating, rough rolling, finish rolling, coiling, steel coil air cooling, flat opening, steel plate heating, quenching and tempering, wherein in the continuous casting process, ladle molten steel comprises the following components ：C：0.03％～0.75％;S≤0.0004％;Ca：0.0006％～0.0016％;P≤0.0040％;Sb≤0.0005％;Sn≤0.0030％;As≤0.0015％;Pb≤0.0005％;N：0.0030％～0.0050％;Ti：0.0108％～0.0200％;H≤0.00015％;Si≤0.70％;Als：0.04％～0.06％; in percentage by mass, wherein the mass percentage relation of the components satisfies that Ca/S is more than or equal to 2, ti/N=3.6-5.0, si+Mn+Cr+Ni+Mo+V+Nb=0.5-12.0%. According to the embodiment of the first aspect of the application, after the blast furnace molten iron-desulfurization-converter smelting-LF refining-RH degassing process, in the continuous casting process, ladle molten steel comprises the following components ：C：0.03％～0.75％;S≤0.0004％,Ca：0.0006％～0.0016％;P≤0.0040％;Sb≤0.0005％,Sn≤0.0030％,As≤0.0015％,Pb≤0.0005％;N：0.0030％～0.0050％,Ti：0.0108％～0.0200％;H≤0.00015％;Si≤0.70％;Als：0.04％～0.06％; in percentage by mass, wherein the mass percentage relation of the components is satisfied that Ca/S is more than or equal to 2, ti/N=3.6-5.0, si+Mn+Cr+Ni+Mo+V+Nb=0.5-12.0, and the balance is Fe and other unavoidab