Duplex stainless steel and manufacturing method thereof

A technology of duplex stainless steel and its manufacturing method, which is applied in the field of economical duplex stainless steel and its manufacturing, can solve the problems of high cost and reduced material weldability, and achieve the effects of good weldability, excellent impact toughness, and excellent corrosion resistance

Active Publication Date: 2012-07-25
BAOSTEEL DESHENG STAINLESS STEEL
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

On the one hand, the cost of the alloy is high, on the other hand, the addition of solid-solution Nb, Ti, and V makes the solid-solution C and N less, and the precipitation of carbides caused by high C content will reduce the weldability of the material.

Method used

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  • Duplex stainless steel and manufacturing method thereof
  • Duplex stainless steel and manufacturing method thereof
  • Duplex stainless steel and manufacturing method thereof

Examples

Experimental program
Comparison scheme
Effect test

experiment example 1

[0075] Experimental example 1: Metallographic structure of alloy

[0076] After grinding and polishing the sample, electrolytic corrosion is carried out. The corrosive agent is 40gKOH+100mlH 2 O, the corrosion current is 0.3-0.8A / cm 2 Finally, the austenite ratio is analyzed by quantitative metallography under a metallographic microscope. The metallographic structure of Example 1 alloy is as figure 1 As shown in the figure, the black structure is ferrite, the white structure is austenite, and the austenite phase accounts for about 53%.

experiment example 2

[0077] Experimental example 2: X-ray diffraction analysis

[0078] The tensile test specimens are manufactured according to JIS-13B standard and stretched to break according to GB / T228-2002 on the MTS-810 tensile machine. 1# is the sample near the fracture, 2# is the sample at the middle of the clamping part and the fracture, and 3# is the sample before stretching. Such as image 3 Shown are the X-ray diffraction analysis of different parts of the material after stretching of the alloy of Example 3. It can be seen from the figure that the austenite peak is higher before stretching, and the closer to the fracture, the austenite peak weakens. This shows that in the process of tensile deformation, part of the austenite undergoes phase transformation and deformed martensite is formed, which makes the amount of austenite less and weakens the diffraction peak of austenite.

experiment example 3

[0079] Experimental example 3: EBSD (electron backscatter diffraction) analysis

[0080] After the alloy was cold deformed by 10%, it was ground, polished and analyzed by EBSD (electron backscatter diffraction). The results of Example 2 are as follows Figure 2a with 2b Shown. among them Figure 2a The image quality (ImageQuality) map. Because the imaging quality reflects the stress distribution and lattice distortion in the tissue, the position with poor imaging quality, that is, the position with darker color, has greater lattice distortion and residual stress. 2b is a phase image (Phase Image), and different colors represent different phases. The blue in the figure is the austenite phase; and because the crystal structure is close to the lattice constant, it is difficult to distinguish between ferrite and martensite, so the red in the figure is ferrite or martensite. Examining the positions A, B, and C in the figure, on the one hand, there are large lattice distortion and...

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Abstract

The invention relates to duplex stainless steel. The duplex stainless steel comprises the following chemical components in percent by weight: 0.01-0.08% of C, 0.2-1.0% of Si, 1.5-3.5% of Mn, 19.0-21.0% of Cr, 1.2-2.8% of Ni, 0.08-0.18% of N, less than or equal to 0.5% of Mo, less than or equal to 1.0% of W, less than or equal to 1.0% of Cu and the balance of Fe and inevitable impurities; PREN (Pitting Resistance Equivalent Number) is 20-24, the martensitic temperature Md formed by strain induction is 60-130 DEG C. A manufacturing method comprises the following steps of: selecting vacuum induction smelting in an electric furnace, argon oxygen decarburization (AOD) or electric furnace, argon oxygen decarburization (AOD), external refining and LF (Ladle Furnace) smelting; carrying out die casting or continuous casting on molten steel, controlling the superheat degree to be 20-50 DEG C in die casting, matching with fast cooling, preventing nitrogen from escaping, and controlling the overheat degree to be 20-50 DEG C and the plate blank casting speed to be 0.8-2m/min; and putting a die-casting blank or a continuous casting blank into a heating furnace for heating to 1100-1250 DEG C, preserving the heat for 0.5-1.5 hours, processing the die-casting blank or the continuous casting blank on a forging production line or a hot-rolling mill group to the needed thickness, then carrying out annealing at the speed of 0.5-2.5min/mm and the temperature of 1030-1150 DEG C. The obtained duplex stainless steel has excellent corrosion resistance and TRIP effect.

Description

Technical field [0001] The invention relates to a duplex stainless steel and a manufacturing method thereof, in particular to an economical duplex stainless steel with excellent corrosion resistance and TRIP (phase transformation induced plasticity) effect and a manufacturing method thereof. Background technique [0002] Duplex stainless steel is composed of ferrite and austenite at room temperature, and each phase ratio is not less than 30%. Due to the existence of the two-phase structure, the duplex stainless steel has the characteristics of ferritic stainless steel and austenitic stainless steel. It is a kind of stainless steel with the best matching of high strength and high corrosion resistance. Compared with ferritic stainless steel, it has high toughness, low brittle transition temperature, intergranular corrosion resistance and weldability, while retaining the advantages of high thermal conductivity and low expansion coefficient of ferritic steel. Compared with austeniti...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/58C22C33/04C21D8/00
Inventor 胡锦程宋红梅张伟江来珠王治宇
Owner BAOSTEEL DESHENG STAINLESS STEEL
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