High-chrome austenitic stainless steel

A technology of austenitic stainless steel and high-chromium austenite, applied in the field of stainless steel, can solve the problems of poor thermal stability, high cost, reduced thermal processing performance and welding performance, and achieve excellent localized corrosion resistance and excellent uniform resistance Corrosion performance, effect of good thermal heating performance

Inactive Publication Date: 2017-05-10
CENT IRON & STEEL RES INST
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Due to the high content of molybdenum, the thermal stability of the existing high-performance austenitic stainless steel is not good. The slab contains low-melting point phases due to segregation, and it is easy to precipitate intermetallic phases during hot working and welding, which leads to its hot workability. and reduced solderability
Subsequently, nitrogen-containing 6Mo (such as 254SMO and AL-6XN) and 7Mo (such as 654SMO) super austenitic stainless steels were developed, although their ingot segregation and hot-working precipitation tendencies are lower than those of nitrogen-free 8Mo high-performance austenitic stainless steels. Reduced, but still can not completely avoid the above problems
Moreover, Mo is a very expensive element, which leads to an increase in the cost of the alloy, which limits the application of the above-mentioned high-performance austenitic stainless steel and super austenitic stainless steel

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0043] Example 1 Solidification structure and hot workability of high chromium austenitic stainless steel

[0044] attached figure 1 The hot workability curves of 4# ingot (29.6Cr-5.2Mo) and 13# ingot (24.3Cr-7.4Mo) are shown. In the hot working temperature range of 1100~1250 ℃, the hot working performance of 4# ingot is higher than that of 13# ingot; the hot working performance of 4# ingot drops obviously at 1250 ℃, and its section shrinkage rate is 8%, which is much lower than that of 13# ingot. 35% in 4# ingot. The results show that too high Mo content and too low Cr content have adverse effects on hot workability in high temperature zone of high chromium austenitic stainless steel ingot.

[0045] attached figure 2 and image 3 The high-magnification structures of 4# ingot (29.6Cr-5.2Mo) and 13# ingot (24.3Cr-7.4Mo) are shown respectively. It can be seen that the segregation degree of 13# ingot (24.3Cr-7.4Mo) is obviously higher than that of 4# ingot due to the low ch...

Embodiment 2

[0048] Example 2 Mechanical properties of high chromium austenitic stainless steel

[0049] attached Figure 7 The mechanical properties of N on high chromium austenitic stainless steel are shown. It can be seen that the strength of high chromium austenitic stainless steel increases with the increase of nitrogen. When the N content reaches above 0.6, the yield strength of the plate can reach above 600MPa. When the N content is higher than 0.9, the impact toughness value at -40°C is lower than 27J, which has no practical engineering application value. The nitrogen content is controlled between 0.60 and 0.90, and high-chromium austenitic stainless steel can obtain good mechanical properties.

Embodiment 3

[0050] Example 3 Localized corrosion resistance of high chromium austenitic stainless steel

[0051] Figure 8 The relationship between the critical crevice corrosion temperature of high-chromium austenitic stainless steel and the value of pitting resistance index PREN is shown. It can be seen that as the PREN value of high-chromium austenitic stainless steel increases, the critical crevice corrosion resistance of stainless steel increases, indicating that its Improved resistance to localized corrosion. When the PREN value is greater than 68, its critical crevice corrosion temperature reaches 60°C and above, which is already higher than the existing 7Mo super austenitic stainless steel 654SMO.

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Abstract

The invention discloses high-chrome austenitic stainless steel and belongs to the technical field of stainless steel. The stainless steel comprises the following ingredients in percentage by weight: less than or equal to 0.035 of C, less than or equal to 1.0 of Si, more than or equal to 3.0 and less than or equal to 6.5 of Mn, less than or equal to 0.035 of P, less than or equal to 0.030 of S, more than or equal to 28.0 and less than or equal to 31.5 of Cr, more than or equal to 18.0 and less than or equal to 25.0 of of Ni, more than or equal to 3.0 and less than or equal to 6.0 of Mo, more than or equal to 0.01 and less than or equal to 3.0 of Cu, more than or equal to 0.60 and less than or equal to 0.90 of N, and the balance of Fe. The alloy also comprises other residual elements and elements for improving the hot working property, like O, Ca, Ti, Nb, B, La, Ce, Al, Zr, V and Mg. Furthermore, the pitting corrosion resistant index [PREN=[Cr(wt.%)+3.3*Mo(wt.%)+30*N(wt.%)] is not less than 68, and the content of Cu is further controlled to be 1.2-3.0. The high-chrome austenitic stainless steel has a high hot working property, a high mechanical property, local corrosion resistance and uniform corrosion resistance.

Description

technical field [0001] The invention belongs to the technical field of stainless steel, in particular to a high-chromium austenitic stainless steel with excellent performance. Background technique [0002] Austenitic stainless steel has been widely used due to its good mechanical properties, corrosion resistance and cold and hot workability. In order to meet the needs of corrosion resistance to harsh media in modern industrial development, the molybdenum content in steel is increased on the basis of 304, 316 and other stainless steels, and high-performance austenitic stainless steels have been developed, such as 317LM and 904L containing 4.5% Mo, containing 6% Al-6X of Mo, followed by high-performance austenitic stainless steel containing 8Mo. Due to the high content of molybdenum, the thermal stability of the existing high-performance austenitic stainless steel is not good. The slab contains low-melting point phases due to segregation, and it is easy to precipitate interme...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C30/02
CPCC22C30/02C22C38/001C22C38/02C22C38/42C22C38/44C22C38/58
Inventor 陈海涛郎宇平屈华鹏
Owner CENT IRON & STEEL RES INST
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