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Ferritic stainless steel

A stainless steel and system technology, applied in furnaces, heat treatment equipment, manufacturing tools, etc., can solve the problems of reduced thermal fatigue characteristics and reduced amount of solid solution Nb, and achieve excellent thermal fatigue characteristics and excellent corrosion resistance to condensed water effects.

Pending Publication Date: 2019-08-02
JFE STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, Nb is easy to combine with C and N in steel to form carbonitrides, and sometimes the amount of solid solution Nb decreases and thermal fatigue properties decrease

Method used

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  • Ferritic stainless steel
  • Ferritic stainless steel
  • Ferritic stainless steel

Examples

Experimental program
Comparison scheme
Effect test

Embodiment

[0092] Steels Nos. 1 to 40 having the component compositions shown in Table 1 were melted and cast in a vacuum melting furnace to produce 30 kg steel ingots. Next, after heating to 1170 degreeC, hot rolling was performed, and it produced the thin slab of thickness 35mm x width 150mm. The thin slab is divided into two halves. Half of it is made into a square bar with a section of 30mm×30mm by forging, annealed in the range of 950-1050°C, and then machined to produce figure 1 The thermal fatigue test piece shown. The thermal fatigue test described later was performed using this test piece. The annealing temperature is set according to the composition while confirming the structure within the temperature range of 950 to 1050°C. The same applies to subsequent annealing.

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Abstract

Provided is a ferritic stainless steel sheet which has excellent scale adhesion and thermal fatigue characteristics, while exhibiting excellent condensed water corrosion resistance. This ferritic stainless steel sheet is configured to have a composition that contains, in mass%, 0.010% or less of C, 1.0% or less of Si, 1.0% or less of Mn, 0.040% or less of P, 0.030% or less of S, from 17.0% to 18.5% (inclusive) of Cr, 0.015% or less of N, from 0.40% to 0.80% (inclusive) of Nb, from 0.10% to 0.40% (inclusive) of Ti, 0.20% or less of Al, from 0.05% to 0.40% (inclusive) of Ni, from 0.01% to 0.30%(inclusive) of Co, from 0.02% to 0.30% (inclusive) of Mo and from 0.02% to 0.40% (inclusive) of Cu, with the balance made up of Fe and unavoidable impurities, while satisfying the following formula (1). C% + N% <= 0.018% (1) In formula (1), C% and N% respectively represent the content (mass%) of C and the content (mass%) of N.

Description

technical field [0001] The present invention relates to a ferritic stainless steel excellent in scale adhesion, thermal fatigue characteristics and condensed water corrosion resistance. Background technique [0002] Among the exhaust system components of automobiles, the exhaust manifold directly connected to the upstream side, especially the engine, is used in a harsh environment with a maximum operating temperature of 800-900°C. Therefore, excellent thermal fatigue characteristics are required for the material, and Nb-added ferritic stainless steel is mainly used. [0003] The Nb added to the ferritic stainless steel improves the high-temperature strength by solid-solution in the steel, and improves the thermal fatigue characteristics. However, Nb easily combines with C and N in the steel to form carbonitrides, and the amount of solid-solution Nb decreases, resulting in a decrease in thermal fatigue properties. As a countermeasure against this, studies have also been mad...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/00C22C38/54C21D9/46C22C38/52
CPCC21D9/46C22C38/00C22C38/52C22C38/54C21D6/002C21D6/004C21D6/007C21D6/02C21D8/0205C21D8/0226C21D8/0236C22C38/02C22C38/04C22C38/004C22C38/001C22C38/002C22C38/48C22C38/50C22C38/06C22C38/44C22C38/42C22C38/46C22C38/12
Inventor 中村彻之石川伸杉原玲子
Owner JFE STEEL CORP