Medium-chromium molybdenum-free ferritic stainless steel extremely low in brittle transition temperature and preparation method thereof

A technology of brittle transition temperature and stainless steel, applied in the field of metallurgy, can solve the problems of thick plate brittle transition temperature control and improvement, high brittle transition temperature, low brittle transition temperature, etc., to promote sustainable development, reduce life cycle cost, improve Effects on service life and safety

Active Publication Date: 2017-02-15
NORTHEASTERN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, from the examples of the above-mentioned patents, it can be found that the impact toughness of the invented ferritic stainless steel at 20°C is 32-130J / cm 2 , the impact energy is 25.6~104J; the impact toughness at -20°C is 15~50J / cm 2 , the impact energy is 12~40J, less than 50% of that at 20°C
However, it can be found from the examples of the above-mentioned patent that for ferritic stainless steel with a chromium content of 20.1%, although the contents of other alloying elements are within the scope specified in this patent, its impact toughness at 0°C is less than 10J / cm 2 , indicating that this patent does not control and improve the brittle transition temperature of ferritic stainless steel plates with a chromium content of more than 18%
However, the above-mentioned patents do not control and improve the mechanical properties of ferritic stainless steel, especially the brittle transition temperature of ferritic stainless steel plates with a thickness of more than 5 mm.
[0009] Through the analysis of the above patents, it can be seen that the brittle transition temperature of medium-chromium-molybdenum-free ferritic stainless steel still needs to be improved. Fully meet the current manufacturing and use requirements, there are still some shortcomings and deficiencies such as high brittle transition temperature and small allowable maximum thickness. It is necessary to develop a medium-chromium-molybdenum-free ferritic stainless steel plate with an extremely low brittle transition temperature

Method used

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  • Medium-chromium molybdenum-free ferritic stainless steel extremely low in brittle transition temperature and preparation method thereof
  • Medium-chromium molybdenum-free ferritic stainless steel extremely low in brittle transition temperature and preparation method thereof
  • Medium-chromium molybdenum-free ferritic stainless steel extremely low in brittle transition temperature and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0036] Smelt in a vacuum induction melting furnace according to the set composition, and cast into a slab; the composition of the slab contains C0.005%, N 0.015%, Si 0%, Mn 0%, P 0.03%, S 0.007% by mass percentage, O 0.005%, Cr 18%, Nb 0.18%, Ti0.05%, Ni 0.4%, Al 0.2%, Cu 0.3%, the balance is iron and unavoidable impurities;

[0037] Heat the slab to 1000°C, keep it warm for 150min, and then hot-roll in multiple passes, the rolling start temperature is 950°C, the reduction in each pass is 30-50%, the final rolling temperature is 650°C, and the cumulative reduction is 96% , to obtain hot-rolled plate;

[0038] Heat the hot-rolled plate to 850°C and hold it for 8 minutes to make it fully recrystallized to complete the hot-rolled annealing, and obtain a medium-chromium-molybdenum-free ferritic stainless steel with a thickness of 8mm and a microstructure such as figure 2 shown. After the Charpy impact test, the impact absorbed energy-temperature curve of the medium-chromium-mol...

Embodiment 2

[0040] Smelted in a vacuum induction melting furnace according to the set composition, and poured into a slab; the composition of the slab contains C0.009%, N 0.011%, Si 0.3%, Mn 0.1%, P 0.02%, S 0.005% by mass percentage, O 0.003%, Cr 20%, Nb 0.13%, Ti0.08%, Ni 0.3%, Al 0.18%, Cu 0.4%, the balance is iron and unavoidable impurities;

[0041] Heat the slab to 1100°C, keep it warm for 90 minutes, and then hot-roll for multiple passes. The rolling start temperature is 1050°C, the reduction in each pass is 30-50%, the final rolling temperature is 700°C, and the cumulative reduction is 97%. , to obtain hot-rolled plate;

[0042] Heat the hot-rolled plate to 900°C and hold it for 7 minutes to make it fully recrystallized to complete the hot-rolled annealing, and obtain a medium-chromium-molybdenum-free ferritic stainless steel with a thickness of 6mm. The impact absorption energy-temperature curve is as follows Figure 4 As shown, the brittle transition temperature is -115°C, the ...

Embodiment 3

[0044] Smelt in a vacuum induction melting furnace according to the set composition, and cast into a slab; the composition of the slab contains C0.015%, N 0.005%, Si 0.5%, Mn 0.2%, P 0.01%, S 0.006% by mass percentage, O 0.002%, Cr 22%, Nb 0.08%, Ti0.1%, Ni 0.2%, Al 0.1%, Cu 0.5%, the balance is iron and unavoidable impurities;

[0045] Heat the slab to 1200°C, keep it warm for 60 minutes, and then hot-roll for multiple passes. The rolling start temperature is 1100°C, the reduction in each pass is 30-50%, the final rolling temperature is 750°C, and the cumulative reduction is 98%. , to obtain hot-rolled plate;

[0046] Heat the hot-rolled plate to 950°C and keep it warm for 6 minutes to make it fully recrystallized to complete the hot-rolled annealing, and obtain a medium-chromium-molybdenum-free ferritic stainless steel with a thickness of 5.5mm. The impact absorption energy-temperature curve is as follows Figure 5 As shown, the brittle transition temperature is -120°C, the...

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Abstract

The invention discloses medium-chromium molybdenum-free ferritic stainless steel extremely low in brittle transition temperature and a preparation method thereof. The medium-chromium molybdenum-free ferritic stainless steel comprises, by mass percentage, 0.005-0.015% of C, 0.005-0.015% of N, less than or equal to 0.5% of Si, less than or equal to 0.2% of Mn, less than or equal to 0.03% of P, less than or equal to 0.01% of S, less than or equal to 0.005% of O, 18-22% of Cr, 0.08-0.18% of Nb, 0.05-0.1% of Ti, 0.2-0.4% of Ni, 0.1-0.2% of Al, 0.3-0.5% of Cu and the balance iron and inevitable impurities, wherein the brittle transition temperature ranges from minus 120 DEG C to minus 100 DEG C. The preparation method comprises the steps of 1, conducting smelting and pouring in a vacuum induction smelting furnace; 2, heating the materials to 1000-1200 DEG C, preserving the temperature for 60-150 minutes, and then conducting hot rolling, wherein the accumulative reduction amount is 96-98%; and 3, heating the materials to 850-950 DEG C, and preserving the temperature for 6-8 minutes. By means of the method, the service life of the medium-chromium molybdenum-free ferritic stainless steel in a severe service environment such as the low temperature environment is prolonged, and safety of the medium-chromium molybdenum-free ferritic stainless steel is improved; steel production cost is lowered; and the targets that in stainless steel production, resources are saved, energy is saved, emission is reduced, and environmental pollution is prevented are finally achieved.

Description

technical field [0001] The invention belongs to the technical field of metallurgy, in particular to a medium-chromium-molybdenum-free ferritic stainless steel with an extremely low brittle transition temperature and a preparation method thereof. Background technique [0002] Ferritic stainless steel refers to a series of iron-based alloys with a body-centered cubic crystal structure, complete ferrite or ferrite-based structure at high temperature and room temperature, and a Cr content greater than 10.5%. For some specific properties, an appropriate amount of elements such as Mo, Ni, Al, Cu, Nb, Ti or Nb+Ti are often added. According to the Cr content in steel, it can be divided into three types: low chromium, medium chromium and high chromium ferritic stainless steel. According to the composition of alloy elements in steel, it can be divided into two types: Fe-Cr series ferritic stainless steel and Fe-Cr-Mo series ferritic stainless steel. [0003] In addition to good stai...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/02C22C38/04C22C38/06C22C38/42C22C38/48C22C38/50C21D8/02C21D1/26
CPCC21D1/26C21D8/0226C21D8/0273C21D2211/005C22C38/001C22C38/004C22C38/02C22C38/04C22C38/06C22C38/42C22C38/48C22C38/50
Inventor 高飞于福晓张向军李成刚曹光明刘振宇
Owner NORTHEASTERN UNIV
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