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CN-119980071-B - Low-density stainless steel, fuel cell interconnection body and preparation method

CN119980071BCN 119980071 BCN119980071 BCN 119980071BCN-119980071-B

Abstract

The application provides a low-density stainless steel, a fuel cell interconnection body and a preparation method thereof, belonging to the field of alloys. The stainless steel includes the following chemical components ：Cr：13%～30%,Al：8%～12%,V：0.25%～0.5%,B：0.01%～0.5%,Zr：0.4%～1.0%,C<0.008%,T.O≤0.002%,N≤0.001%,Si：0.15%～0.3%,Mn：0.1%～0.8% and Fe. The chemical components of stainless steel are reasonably designed. Al is introduced to reduce the alloy density, and the low-density FeAl intermetallic compound separated out in the aging process has the advantage of improving the mechanical property at medium and high temperatures. The comprehensive effect of B and Zr can improve the medium-temperature comprehensive performance of the alloy at 600-900 ℃. Meanwhile, the Al position of the V occupying intermetallic compound is introduced, so that the stability of the Fe-Al intermetallic compound is improved. Therefore, the density of the fuel cell interconnection body is reduced on the basis of meeting the requirements that the fuel cell interconnection body has high strength, high toughness and oxidation resistance.

Inventors

  • JIA YANAN
  • LI ZHENRUI
  • ZHANG ZHIWEI

Assignees

  • 北京北冶功能材料有限公司

Dates

Publication Date
20260512
Application Date
20250214

Claims (8)

  1. 1. A low-density stainless steel, which comprises the following chemical components ：Cr：13%～30%,Al：8%～12%,V：0.25%～0.5%,B：0.01%～0.5%,Zr：0.4%～1.0%,C<0.008%,T.O≤0.002%,N≤0.001%,Si：0.15%～0.3%,Mn：0.1%～0.8% and Fe in mass fraction; The chemical components satisfy the following relation: 24≤[Al]/[V]≤32 Wherein [ V ] represents the mass fraction of V and [ Al ] represents the mass fraction of Al; The chemical components satisfy the following relation: 0.01≤([Zr]+1.1[B])/([Al]+[V])≤0.2 Wherein [ Zr ] represents the mass fraction of Zr, [ B ] represents the mass fraction of B, [ V ] represents the mass fraction of V, and [ Al ] represents the mass fraction of Al.
  2. 2. A method of making the stainless steel of claim 1, the method comprising: vacuum refining is carried out on molten steel, and when the T.O of the molten steel is less than or equal to 0.002%, alloy containing Al, V, B and Zr is added into the molten steel to obtain alloyed molten steel; Pouring the alloyed molten steel to obtain the stainless steel.
  3. 3. The method of claim 2, wherein the time of the vacuum refining and the pressure of the vacuum refining satisfy the following relationship: When T is less than 0.2T, P is 1 Pa-5 Pa; When 0.2T < t <0.6T, P is 0.1Pa to 0.5Pa; When t is more than 0.6T, P is 1 Pa-2 Pa; wherein T represents the time of vacuum refining, P represents the pressure of vacuum refining, T represents the total time of vacuum refining, and T is 0.5-0.7 h.
  4. 4. A fuel cell interconnect made from the stainless steel of claim 1.
  5. 5. The fuel cell interconnect of claim 4, wherein the fuel cell interconnect meets at least one of the following properties: alloy density is 7.0g/cm 3 ～7.2g/cm 3 ; Oxidizing the total thickness of the oxide film for 30000h at 900 ℃ in an O 2 -H 2 O atmosphere to be less than 15 mu m; The tensile strength Rm is more than or equal to 250MPa at 900 ℃; the yield strength Rp0.2 is more than or equal to 210MPa at 900 ℃; the thermal expansion coefficient at 600 ℃ to 900 ℃ is 11 multiplied by 10 -6 /K～13×10 -6 /K.
  6. 6. A method of making the fuel cell interconnect of claim 4 or 5, the method comprising: heating, forging and tempering the stainless steel according to claim 1 in sequence for multiple times to obtain a flat blank; carrying out multi-pass hot rolling and annealing softening on the flat blank to obtain a hot rolled strip blank; performing intermediate heat treatment, multi-pass cold rolling and solution treatment on the hot rolled strip blank to obtain a strip; and (5) carrying out stamping forming and time-efficient treatment on the strip to obtain the fuel cell interconnection body.
  7. 7. The method of claim 6, wherein the stamping forming comprises the following parameters of heating temperature of 200-400 ℃, heat preservation time of 20-120 min and hydrogen spraying amount of more than or equal to 5m 3 /h.
  8. 8. The method according to claim 6, wherein the aging treatment comprises the following parameters of 400-500 ℃, a heat preservation time of 60-90 min and a hydrogen spraying amount of 20m 3 /h or more.

Description

Low-density stainless steel, fuel cell interconnection body and preparation method Technical Field The application relates to the technical field of alloys, in particular to a low-density stainless steel, a fuel cell interconnection body and a preparation method thereof. Background The worldwide urgent need to reduce the emission of greenhouse gases and control global warming has attracted considerable attention from the industry. The weight reduction thought mainly comprises two categories, namely, the weight reduction thought is that the weight of the material is reduced by improving the strength of the material so as to achieve the aim of reducing the weight of the whole structure. The other is to develop low-density materials to achieve the purpose of light weight. Taking an electric automobile as an example, the driving range of the electric automobile can be increased by 5.5% every 10% of the whole automobile weight. The three-electricity system of the new energy automobile accounts for about 1/4 of the whole car preparation quality, and the light weight is the key point for solving the problem. The light element can expand the lattice constant of the steel while reducing its density by virtue of the low atomic weight. But brings a series of problems at the same time, and the light elements have great influence on the thermodynamic stability of the allotrope of the steel. For example, the excessive use of aluminum without carbon compensation will result in the ferrite phase being able to exist stably at different temperatures below the solidus, so that the possibility of tissue optimization by heat treatment is eliminated. In addition, precipitation of brittle phases is detrimental to the mechanical properties of the material, and in solid fuel cells, the material of the connector is 80% or more of the total weight. At present, the more careful research on the solid oxide fuel cell is that four types of ferrite stainless steel connectors are Crofer22 APU,SUS430,X10CrAl18 and ZMG 232. A comparison of representative ferritic Fe-Cr alloys was made with ZMG232 developed by HITACHI METALS and Crofer22 APU alloys published by ThyssenKrupp VDM in 2003. Later optimized ZMG232L and Crofer22H were further developed, respectively. Although all four alloys were excellent, the above alloys had densities of 7.8g/cm 3～8.0g/cm3. Therefore, how to reduce the density of the fuel cell interconnect on the basis of satisfying the requirements of high strength, high toughness and oxidation resistance of the fuel cell interconnect is a technical problem which is urgently needed to be solved at present. Disclosure of Invention The application provides a low-density stainless steel, a fuel cell interconnection body and a preparation method thereof, which are used for solving the technical problem of how to reduce the density of the fuel cell interconnection body on the basis of meeting the requirements that the fuel cell interconnection body has high strength, high toughness and oxidation resistance. In a first aspect, the present application provides a low-density stainless steel comprising the following chemical components ：Cr：13%～30%,Al：8%～12%,V：0.25%～0.5%,B：0.01%～0.5%,Zr：0.4%～1.0%,C<0.008%,T.O≤0.002%,N≤0.001%,Si：0.15%～0.3%,Mn：0.1%～0.8% and Fe in mass fraction. Optionally, the chemical composition satisfies the following relation: 24≤[Al]/[V]≤32 wherein [ V ] represents the mass fraction of V and [ Al ] represents the mass fraction of Al. Optionally, the chemical composition satisfies the following relation: 0.01≤([Zr]+1.1[B])/([Al]+[V])≤0.2 Wherein [ Zr ] represents the mass fraction of Zr, [ B ] represents the mass fraction of B, [ V ] represents the mass fraction of V, and [ Al ] represents the mass fraction of Al. In a second aspect, the present application provides a method for producing the stainless steel according to any one of the first aspects, the method comprising: vacuum refining is carried out on molten steel, and when the T.O of the molten steel is less than or equal to 0.002%, alloy containing Al, V, B and Zr is added into the molten steel to obtain alloyed molten steel; Pouring the alloyed molten steel to obtain the stainless steel. Optionally, the time of the vacuum refining and the pressure of the vacuum refining satisfy the following relationship: When T is less than 0.2T, P is 1 Pa-5 Pa; When 0.2T < t <0.6T, P is 0.1Pa to 0.5Pa; When t is more than 0.6T, P is 1 Pa-2 Pa; Wherein T represents the time of vacuum refining, P represents the pressure of vacuum refining, T represents the total time of high-temperature refining, and T is 0.5-0.7 h. In a third aspect, the present application provides a fuel cell interconnect made from the stainless steel of any one of the first aspects. Optionally, the fuel cell interconnect meets at least one of the following properties: alloy density is 7.0g/cm 3～7.2g/cm3; Oxidizing the total thickness of the oxide film for 30000h at 900 ℃ in an O 2-H2 O atmosphere to be less