阅读说明：本技术 一种高硬高强可折叠不锈钢箔 (High-hardness high-strength foldable stainless steel foil ) 是由 孟利 张宁 杨勇 于 2019-10-28 设计创作，主要内容包括：一种高硬高强可折叠不锈钢箔,属于不锈钢箔技术领域。以奥氏体不锈钢薄板为原料,合金成分范围质量百分比：0.1％≤C+N≤0.2％,6％≤Ni+Cu≤8％,0.5％≤Mn≤1.5％,16％≤Cr≤18％,0.01％≤Mo≤0.03％,0.3％≤Si≤1％,余量为Fe；基于M<Sub>D30/50</Sub>和层错能γ<Sub>SF</Sub>公式,在以上的成分范围内调整,通过经3-7道次轧制与退火得到马氏体占比50％-80％的不锈钢箔产品。钢箔厚度为15μm以上50μm以下,硬度≥580HV,抗拉强度≥1800MPa；折弯角度可达到≥170°,承受弯折半径R达到1.5mm-8mm,折叠次数≥200000不断裂。(A high-hardness high-strength foldable stainless steel foil belongs to the technical field of stainless steel foils. The austenitic stainless steel sheet is used as a raw material, and the alloy comprises the following components in percentage by mass: c and N are more than or equal to 0.1 percent and less than or equal to 0.2 percent, Ni and Cu are more than or equal to 6 percent and less than or equal to 8 percent, Mn is more than or equal to 0.5 percent and less than or equal to 1.5 percent, Cr is more than or equal to 16 percent and less than or equal to 18 percent, Mo is more than or equal to 0.01 percent and less than or equal to 0.03 percent, Si is more than or equal to 0.3 percent and less than or; based on M D30/50 And stacking fault energy gamma SF The formula is adjusted in the above composition range, and martensite accounts for 50% by rolling and annealing for 3-7 times80% stainless steel foil product. The thickness of the steel foil is more than 15 mu m and less than 50 mu m, the hardness is more than or equal to 580HV, and the tensile strength is more than or equal to 1800 MPa; the bending angle can reach more than or equal to 170 degrees, the bearing bending radius R reaches 1.5mm-8mm, and the bending frequency is more than or equal to 200000 without fracture.)

1. The high-hardness high-strength foldable stainless steel foil is characterized in that an austenitic stainless steel sheet is used as a raw material, and the alloy components are as follows by mass percent: c and N are more than or equal to 0.1 percent and less than or equal to 0.2 percent, Ni and Cu are more than or equal to 6 percent and less than or equal to 8 percent, Mn is more than or equal to 0.5 percent and less than or equal to 1.5 percent, Cr is more than or equal to 16 percent and less than or equal to 18 percent, Mo is more than or equal to 0.01 percent and less than or equal to 0.03 percent, Si is more than or equal to 0.3 percent and less than or; based on M _D30/50And stacking fault energy gamma _SFAdjusting the formula within the above component range, and obtaining a stainless steel foil product with the martensite accounting for 50% -80% by rolling and annealing for 3-7 times;

M _D30/50is the temperature of 50% martensite formation under 30% cold deformation, gamma _SFIs room temperature stacking fault energy mJ/m ²；

M _D30/50＝551-462(C+N)-29(Ni+Cu)-8.1(Mn)-13.7(Cr)-18.5(Mo) -9.2(Si) -1.42(G-8) DEG C, the alloy components are mass fraction, and G is grain size grade number;

γ _SF＝γ _0SF+1.59Ni-1.34Mn+0.06Mn ²-1.75Cr+0.01Cr ²+15.21Mo-5.59Si-60.69(C+1.2N) ^1/2+26.27(C+1.2N)×(Cr+Mn+Mo) ^1/2+0.61[Ni×(Cr+Mn)] ^1/2(mJ/m ²) Wherein γ is _0SF＝38mJ/m ²。

2. The high-hardness high-strength foldable stainless steel foil as claimed in claim 1, wherein a steel plate with a raw material thickness of 0.2mm-2.5mm is selected, the steel foil with a thickness of 15 μm-50 μm is rolled through 3-7 passes, the single-pass deformation amount is 15% -60%, and the sandwich structure with coexistent austenite and martensite in the thickness direction of the steel foil is obtained through softening annealing among the passes and final stress relief annealing.

3. The high-hardness high-strength foldable stainless steel foil as claimed in claim 1, wherein the high-hardness high-strength stainless steel foil with hardness not less than 580HV, yield strength not less than 1800MPa and tensile strength not less than 1800MPa is obtained through the coordination of martensite phase transformation strengthening and work hardening, solid solution strengthening and structure refinement; can be folded, the bearing bending angle is more than or equal to 170 degrees, and the folding times are more than or equal to 200000 without fracture when the bending radius R is 1.5mm-8 mm.

4. The high-hardness high-strength foldable stainless steel foil as claimed in claim 1, wherein the stainless steel foil is of an austenite dual-phase structure with a body-centered cubic BCC structure martensite + face-centered cubic FCC structure, the martensite structure is induced by rolling deformation, the austenite structure is formed by annealing reverse transformation and consists of retained austenite, the martensite structure of the BCC structure presents α line texture, namely near {223} - {112} <110> component and near Taylor texture, and the austenite structure is of a typical FCC structure metallic copper type {112} <111>, Goss {011} <100> and a brass type {011} <211> rolling texture.

Technical Field

The invention belongs to the technical field of stainless steel foils, and particularly provides a high-hardness high-strength foldable stainless steel foil with the thickness of more than 15 micrometers and less than 50 micrometers.

Background

Along with the high-speed development of modern high-end manufacturing, high-end products require more precision, high integration, light weight and high performance, and foil sheets in the high-end products are required to be thinner and have more excellent performance, and the high-strength foldable and reboundable stainless steel foil has wide application requirements in various fields such as spring sheets, gasket sheets, precision parts, etching pieces, photoelectric protection cables, temperature controllers, automobile expansion valve membranes, elastic springs, precision electronics, automobile parts, camera parts, air conditioner pressure switch membranes, electronic appliances, hardware stamping parts, air compressor spring sheets, injection needle piston ring expansion rings and the like. Particularly, with the arrival of the 5G era, the wearing technology leads the foldable ultrathin display panel with the large and wide screen to adopt the high-performance supporting pad membrane, so that the requirements of maintaining the overall strength, supporting the large screen and stably bearing the core component are met, and higher requirements are provided for the performance of the metal foil of the supporting pad membrane, namely the characteristics of high hardness, high wear resistance, flexibility, foldability, corrosion resistance and ultrahigh strength.

At present, only a few reports are made on the preparation of stainless steel foil:

1) CN1109121C, discloses an ultra-thin stainless steel foil with a thickness of 25 μm or less. The number of inclusions having a major diameter of 5 μm or more is defined as 1mm per one row in the rolling direction ²The average number of the cross sections is 3 or less, which solves the technical problem in the etching process. However, the patent does not describe the structure of the steel foil such as phase and grain, and the mechanical properties such as hardness and strength.

2) CN105829567(A, B), discloses a stainless steel foil with a thickness of 60 μm or less and a method for producing the same. The stainless steel foil is obtained by controlling the recrystallization ratio to 90% or more, the recrystallized grain size not to be too large (3 or more grains in the plate thickness direction), and the surface nitrogen concentration, and the phase distribution of the stainless steel foil is controlled by adjusting the rolling reduction of the final pass and the final annealing conditions.

3) CN107923012A, CN108713067A and CN104093872A disclose austenitic, martensitic and ferritic stainless steel foils and manufacturing methods thereof, respectively. However, the patents mentioned in this section all result in stainless steel foils with a predominantly recrystallized structure, suitable for battery case applications, and not high in hardness and strength.

In conclusion, the high-hardness high-strength foldable stainless steel foil and the preparation technology thereof are only reported in public.

Disclosure of Invention

The invention aims to provide a high-hardness high-strength foldable stainless steel foil, which is 15-50 mu m thick and meets the application requirements of high-hardness high-strength foldable long-life light metal foil gaskets, spring plates and the like.

The invention takes an austenitic stainless steel sheet as a raw material, and the main alloy components are in the following ranges (mass percent): c and N are more than or equal to 0.1 percent and less than or equal to 0.2 percent, Ni and Cu are more than or equal to 6 percent and less than or equal to 8 percent, Mn is more than or equal to 0.5 percent and less than or equal to 1.5 percent, Cr is more than or equal to 16 percent and less than or equal to 18 percent, Mo is more than or equal to 0.01 percent and less than or equal to 0.03 percent, Si is more than or equal to 0.3 percent and less than or. M based on _D30/50And stacking fault energy gamma _SFAnd adjusting the formula within the above composition range, and obtaining a stainless steel foil product with the martensite accounting for 50% -80% by multi-pass rolling and annealing.

M _D30/50The temperature (. degree. C.) at which 50% of martensite is formed under 30% cold deformation, γ _SFIs the room temperature stacking fault energy (mJ/m) ²). Many scholars consider M _D30/50The larger the value, the greater the tendency of cold deformation to induce martensite, and γ _SFA value of less than 20mJ/m ²The tendency of cold deformation to induce martensite is large.

M _D30/50551-cozeb 462(C + N) -29(Ni + Cu) -8.1(Mn) -13.7(Cr) -18.5(Mo) -9.2(Si) -1.42(G-8) (° C), wherein the alloy components are in mass fraction, and G is the grain size grade number (according to GB/T6394);

γ _SF＝γ _0SF+1.59Ni-1.34Mn+0.06Mn ²-1.75Cr+0.01Cr ²+15.21Mo-5.59Si-60.69(C+1.2N) ^1/2+26.27(C+1.2N)×(Cr+Mn+Mo) ^1/2+0.61[Ni×(Cr+Mn)] ^1/2(mJ/m ²) Wherein γ is _0SF＝38mJ/m ²。

Selecting a steel plate with the thickness of 0.2mm-2.5mm as a raw material, rolling the steel plate to a steel foil with the thickness of 15 μm-50 μm through 3-7 passes of rolling, wherein the single-pass deformation is 15% -60%, and performing softening annealing and final stress relief annealing between the rolling passes to obtain a sandwich structure with coexisting austenite and martensite in the thickness direction of the steel foil, namely the layered distribution of a surface structure which takes an austenite phase as a main phase and an internal structure which takes a martensite phase as a main phase is shown in figure 1.

The stainless steel foil provided by the invention is of an austenite dual-phase structure with a Body Centered Cubic (BCC) structure martensite + Face Centered Cubic (FCC) structure, rich substructures (a tangle dislocation configuration and small-angle grain boundaries) and a large amount of fine grains exist in martensite and austenite regions, a martensite structure is induced by rolling deformation, an austenite structure is formed by annealing reverse transformation and residual austenite, the proportion of the martensite structure in a final structure is 50-80%, and the balance is an austenite structure, the martensite structure of the BCC structure presents α line texture (near {223} - {112} <110> component) and near Taylor texture, and the austenite structure is a typical FCC structure metal copper type ({112} <111>), Goss ({011} <100>) and brass type ({011} <211>) rolling texture.

Work hardening occurs in the rolling process, austenite is transformed into martensite, the deformation transformed martensite structure ensures the high hardness and the high strength of the steel foil, and the deformation residual austenite structure ensures the strength and the toughness. Abundant entanglement is generated in the deformation and phase change processes, the higher dislocation density in the dislocation configuration ensures the strength and hardness of the steel foil, and the refined grain structure promotes the improvement of the strength and toughness, especially under the condition that two phases exist in a staggered manner; meanwhile, in the rolling deformation process, martensite and austenite two-phase crushing exist in a staggered mode, and the formation of a strong texture is hindered to a certain extent due to the existence of a two-phase interface, so that strong anisotropy of performance caused by excessively strong deformation texture is avoided. In addition, the appropriate contents of C and N promote the solid solution strengthening of austenite phase and martensite phase and the work hardening rate; the 'fragmentation' of the deformed structure in the rolling process promotes the generation of fine-grained strengthening.

In conclusion, the high-hardness and high-strength stainless steel foil with the hardness of more than or equal to 580HV, the yield strength of more than or equal to 1800MPa and the tensile strength of more than or equal to 1800MPa is obtained through the coordination of martensite phase transformation strengthening and work hardening, solid solution strengthening and structure refining. The folding device can be folded, the bearing bending angle is more than or equal to 170 degrees, and when the bending radius R is 1.5mm-8mm, the folding times are more than or equal to 200000 and the folding device is not broken; the stainless steel foil is of an austenite + martensite dual-phase structure.

Drawings

FIG. 1 is a microstructure view of a steel foil according to the present invention in the full thickness direction on the side thereof (the gray regions are austenite phases; the black regions are martensite phases).

Detailed Description