High-nitrogen austenitic stainless steel

Inactive Publication Date: 2006-02-16

DAIDO STEEL CO LTD

2 Cites 258 Cited by

AI-Extracted Technical Summary

Problems solved by technology

The above-described austenitic stainless steels, generally believed as highly corrosion resistant, can however show only a limited resistance against local corrosion, and th...

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Benefits of technology

[0068] The high-nitrogen austenitic stainless steel of this invention can be worked so as to produce wire product or sheet product. In this case, a more distinct level of strengthening is available by carrying out the area-reducing process at the final stage of the wire making or sheet making by cold wire drawing or cold rolling. After such process, Cr-base nitride having a diameter of 2 μm or larger is observed neither in the section of a wire product 100, shown in FIG. 1, normal to the axis thereof, nor in the section of a sheet product 150, shown in FIG. 2, normal to the drawing direction thereof, and it is made possible to obtain the wire product or sheet product as having a mean grain size (in circle-converted diameter) of the austenitic matrix phase of 100 μm or smaller. The refinement of the mean grain size of the austenitic matrix phase makes it possible to obtain the wire product or sheet product having an extremely high strength and an excellent corrosion resistance. A specific attainable level of strength may be 1,500 MPa or more, or may be even 2,000 MPa or more (strengthening up to 2,500 MPa or around, for example, is attainable, with the upper limit value not specifically limited).

[0069] The finally-obtained grain size of the austenitic matrix phase of the wire product or sheet produ...

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Abstract

This invention provides a high-nitrogen austenitic stainless steel superior to the conventional one both in the corrosion resistance and strength, despite a low Ni content, characterized in having a Fe content of 50% by mass or more; containing Cr: 15.0% by mass to 35.0% by mass, Mo: 0.05% by mass to 8.0% by mass %, Mn: 0.2% by mass to 10.0% by mass, Cu: 0.01% by mass to 4.0% by mass and N: 0.8% by mass to 1.5% by mass, both ends inclusive, having a C content of 0.20% by mass or less, a Si content of 2.0% by mass or less, a P content of 0.03% by mass or less, a S content of 0.05% by mass or less, a Ni content of 0.5% by mass or less, an Al content of 0.03% by mass or less, and an 0 content of 0.020% by mass or less; wherein the contents of Cr, Mo, N and Mn are adjusted so that a compositional parameter η expressed by the equation:

η≡(W_Cr+3.3W_Mo+16W_N)/W_Mn

- where W_Cris Cr content (% by mass), W_Mois Mo content (% by mass) W_Nis N content (% by mass) and W_Mnis Mn content (% by mass) has a value of 5 or above. and optionally further containing either one of, or both of: W: 0.01% by mass to 1.0% by mass; and Co: 0.01% by mass to 5.0% by mass, both ends inclusive; and optionally further containing at least one of: Ti: 0.01% by mass to 0.5% by mass; Nb: 0.01% by mass to 0.5% by mass; V: 0.01% by mass to 1.0% by mass; and Ta: 0.01% by mass to 0.5% by mass, both ends inclusive; and optionally further containing at least one of: B: 0.001% by mass to 0.01% by mass; Zr: 0.01% by mass to 0.50% by mass; Ca: 0.001% by mass to 0.01% by mass; and Mg: 0.001% by mass to 0.01% by mass, both ends inclusive; and optionally further containing either one of, or both of: Te: 0.005% by mass to 0.05% by mass; and Se: 0.01% by mass to 0.20% by mass, both ends inclusive.

Technology Topic

Austenitic stainless steelAl content +3

Image

Examples

Experimental program(1)

Example

[0085] In each of Examples 5, 6 and 13, the 50-kg steel ingot was homogenized under heating, then hot-forged, and hot-rolled so as to obtain a 12.5-mm-diameter wire product, subjected to solution heat treatment under the condition determined in the above, and cold-drawn with reductions of area of 50% and 70% so as to obtain wire products of 8.8 mm in diameter and 6.8 mm in diameter, respectively. These wire products were also subjected to measurements of tensile strength and mean grain size, similarly to as described in the above. Again in each of Examples 5, 6 and 13, the 50-kg steel ingot was homogenized under heating, then hot-forged, and hot-rolled so as to obtain a 5-mm-thick sheet product, subjected to solution heat treatment under the condition determined in the above, and cold-rolling with drafts of 50% and 70% so as to obtain sheet products of 2.5 mm thick and 1.5 mm thick, respectively. These sheet products were also subjected to measurements of tensile strength and mean grain size, similarly to as described in the above. Results are shown in Table 3 and Table 4.

[0086] It was found from the results shown in Table 3 that the steels of Examples 1 to 13 were very excellent in both of the tensile strength after the solution heat treatment and corrosion resistance indicated by the pitting corrosion potential, and were successful in attaining higher levels of strength and corrosion resistance as compared with those of ever-known austenitic stainless steels SUS836L, SUS329J4L and SUS316, shown in Comparative Examples 12 to 14, respectively. It was also found from the results shown in Table 4 that the steels of this invention, cold-processed into forms of wire product and sheet product, successfully achieved a super-high strength of as high as 2,000 MPa or above.

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PUM

Property	Measurement	Unit
Temperature	1100.0	°C
Temperature	1250.0	°C
Percent by mass	0.01	mass fraction
tensile		MPa
Particle size		Pa
strength	10

Description & Claims & Application Information

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Self-leveling cementitious composition with controlled rate of strength development and ultra-high compressive strength upon hardening and articles made from same

ActiveUS20090239977A1High strengthImprove the immunitySolid waste managementTriethanolamineFiber reinforcement

Owner:UNITED STATES GYPSUM CO +1

Classification and recommendation of technical efficacy words

High strength
Excellent corrosion resistance

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Improved strength Materials science Ultimate tensile strength

High-nitrogen austenitic stainless steel

AI-Extracted Technical Summary

Problems solved by technology

Benefits of technology

Abstract

Image

Examples

Example

PUM

Description & Claims & Application Information

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