Preparation process of stainless steel-TiB2 gradient rolled composite plate based on heterogeneous interface cooperative regulation and control

Abstract

The invention discloses a preparation process of a stainless steel-TiB2 gradient rolled composite plate based on heterogeneous interface cooperative regulation and control, relates to the technical field of metal matrix composite material preparation, and aims to solve the technical barriers of uneven interface performance caused by interface thermal stress concentration, high rolling breakage rate and process parameter mismatch in the preparation of the existing stainless steel-TiB2 composite plate. The invention provides a high-precision composite plate preparation method based on gradient temperature field collaborative multi-pass rolling, a collaborative technology combining argon arc welding sealed packaging and dynamic reduction rate regulation and control is adopted, and by inhibiting generation of a high-temperature oxide layer, reducing interdiffusion resistance of a metal-ceramic heterogeneous interface, optimizing plastic flowing of TiB2 particles and achieving directional diffusion of interface elements, the high-precision composite plate is prepared. The thickness of a diffusion layer is 50 + / -5 microns, the limitation of a traditional explosive cladding and single rolling process is replaced, and the composite manufacturing process which is stable in interface strength, larger than or equal to 220 MPa in shear strength, larger than 90% in production qualification rate and suitable for large-scale industrial requirements is provided for the high-performance metal-based composite material.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation of metal matrix composites, and particularly to a preparation process of a stainless steel-TiB2 gradient rolling composite plate based on cooperative regulation of heterogeneous interfaces. Background Art

[0002] As the core material for hot-end components of aero-engines and shielding structures of nuclear reactors, the domestic production process of stainless steel-TiB2 composite plates has long been restricted by bottlenecks in interface performance and preparation technology: Although the imported products have an interfacial shear strength of ≥200 MPa, they are subject to export control and high costs; Due to the problem of severe thermal shock in the domestic traditional explosive cladding process (such as CN87102426.8), the reinforcing phase is excessively broken, the material loss is serious, and the environmental protection and safety hazards are prominent, which has been listed as a technology direction restricted by the state; The existing vacuum rolling process (such as CN201910940487.4) has technical defects such as insufficient processing accuracy and difficulty in large-scale production due to the dual constraints of equipment precision and energy consumption level, and there has been no effective breakthrough in the combined application of composite metal ceramics and stainless steel.

[0003] In view of this, the present application is specifically proposed. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation process of a stainless steel-TiB2 gradient rolling composite plate based on cooperative regulation of heterogeneous interfaces to solve the problems mentioned in the above background art.

[0005] To solve the above technical problems, a preparation process of a stainless steel-TiB2 gradient rolling composite plate based on cooperative regulation of heterogeneous interfaces provided by the present invention includes the following steps: Step 1, matrix pretreatment: Select a 304 stainless steel tubular matrix (outer diameter 24 mm, inner diameter 16 mm, length 30 mm), and a 304 stainless steel plug (diameter M16, length 12 mm) of the same material; This provides a standardized basic component for the subsequent preparation of the composite plate, which can ensure the matching accuracy of each component in the subsequent process and reduce the process error caused by size differences.

[0006] Step 2. Powder pretreatment and filling: Mix TiB2 powder (particle size 0.5 - 2μm, purity ≥99.9%) with 200 - 400 mesh Fe powder (Fe content ≥99.5%) at a mass ratio of 1:1.2. After mechanical ball milling (rotation speed 300 rpm - 400 rpm, time 2 - 4 h, ball-to-material ratio 10:1, grinding balls made of cemented carbide with a diameter of 5 - 10 mm, absolute ethanol as the wet milling medium), then fill it into the matrix cavity with a filling density ≥95%. Before mixing, vacuum dry the powder to ensure that the powder system is pure and has sufficient fluidity. By strictly controlling the particle size, purity, mixing ratio of the powder, as well as the ball milling and drying conditions, the TiB2 powder and Fe powder can be evenly mixed, ensuring the filling density and good fluidity of the powder in subsequent processing, providing guarantee for the formation of a uniform and excellent composite plate.

[0007] Step 3. Sealing of the encapsulation structure: Engage the stainless steel plug with the nut, and then use argon arc welding (current 80 - 120 A, Ar purity ≥99.99%, gas flow rate 15 L / min) to weld the stainless steel plug to the end face of the matrix. After welding, coat the outer surface with a silicon-aluminate-based high-temperature resistant inorganic glue (temperature resistance ≥1700℃, thickness 50 - 100μm, thermal expansion coefficient 8.2×10 -6 / ℃); This double-sealing protection measure can effectively isolate air and impurities, provide a good internal environment for the subsequent heating and rolling processes, prevent powder oxidation and contamination, and ensure the quality of the composite interface.

[0008] Step 4. Gradient heating and dynamic temperature control: Place the encapsulated body in a box-type resistance furnace, heat it at a gradient of 5℃ / min to 1200℃ ± 20℃, and hold for 1 - 1.5 h. Precisely controlling the heating rate, holding temperature, and time can fully austenitize the matrix and activate the interface atoms at the same time, creating favorable conditions for the diffusion and metallurgical bonding between atoms during the subsequent rolling process, and promoting the formation of a good bonding interface between stainless steel and TiB2 particles.

[0009] Step 5. Multi-pass rolling and microstructure control: Use a two-high hot rolling mill (roll diameter 94 - 86 mm, rolling pressure 650 kN) for longitudinal rolling, with the rolling direction parallel to the two different interfaces of the matrix. The reduction rate of the initial pass ≤30%, and the cumulative reduction rate ≥85%; After each pass of rolling, heat it in the furnace for holding (800℃ × 10 - 30 min); By controlling the rolling equipment parameters, rolling direction, reduction rate, and heat holding conditions in the furnace, the interface bonding and microstructure uniformity can be optimized, the slip system can be fully activated, the thermal stress distribution can be optimized, and at the same time, the processing stress can be eliminated by dynamic recrystallization, realizing the precise control of the microstructure and properties of the composite plate.

[0010] Further, in the first step, the composition of the 304 stainless steel substrate (mass percentage): Cr (18% - 20%), Ni (8% - 10.5%), the balance being Fe and impurities, and the trace elements comply with GB / T 20878.

[0011] Further, in the second step: TiB2 powder (0.5 - 2μm) and 200 - 400 mesh Fe powder are mixed at a mass ratio of 1:1.2. After mechanical ball milling to achieve full homogenization of the powder, adsorbed water and volatile components are effectively removed through a vacuum drying process, and the composite powder system with excellent fluidity is injected into the substrate cavity with a filling density of ≥95%.

[0012] Further, in the third step, the stainless steel plug and the stainless steel nut are mechanically engaged to reduce the relative slip between the interfaces during rolling, and the weld gap during welding is ≤0.1mm.

[0013] Further, in the fourth step, the oxygen content in the furnace during the gradient heating stage is ≤50ppm, the temperature fluctuation during the holding stage is ≤±10°C, and the austenite grain size of the substrate is ≤50μm (the proportion of γ-Fe phase is ≥95%).

[0014] Further, in the fifth step, the rolling direction is parallel to the long axis direction of the stainless steel substrate grains, the linear speed of the rolling mill is 15 - 20m / min, the final rolling temperature is ≥800°C, and the final rolling thickness of the sheet is 3 - 5mm (tolerance ±0.1mm).

[0015] Compared with the prior art, the beneficial effects of the present invention are: Through the gradient heating coupled with multi-pass rolling process, compared with the traditional explosive rolling or unidirectional hot rolling method, the metallurgical bonding strength between stainless steel and TiB2 particles is significantly improved, and the interface shear performance reaches the leading level in the industry. The material utilization rate is greatly increased, the equipment loss is significantly reduced, and at the same time, the high-temperature creep resistance performance is breakthrough optimized, showing unique technical advantages in extreme working conditions such as hot-end components of aeroengines.

[0016] Through the double protection of argon arc welding sealing and high-temperature resistant inorganic glue coating, the thickness of the matrix oxide layer is significantly reduced, and the thickness of the oxide layer at the composite interface is reduced to an extremely low level. The oxygen content at the interface is reduced to an extremely low level, effectively eliminating the atomic diffusion barrier, and enabling a leapfrog improvement in the metallurgical bonding rate between TiB2 particles and stainless steel.

[0017] Before rolling, the TiB2 / Fe mixed powder was mechanically ball milled (rotation speed 300 rpm - 400 rpm, ball milling time 3 - 5 h, ball-to-material ratio 10:1, absolute ethanol as the wet milling medium), combined with vacuum drying at 100 °C for 2 h and the design of the longitudinal rolling direction, effectively improving the surface activation energy of TiB2 particles, significantly enhancing the interfacial bonding strength between the reinforcement phase and the matrix, and at the same time improving the uniformity of the three-dimensional spatial distribution of the microparticles, and significantly reducing the difference rate of the mechanical properties between the longitudinal and transverse directions of the composite plate.

[0018] In multi-pass rolling, the intermittent furnace holding technology was introduced, combined with the pre-pressing process of a four-column hydraulic press, effectively eliminating residual stress and improving the powder density, achieving fine control of the final rolling plate thickness tolerance, and achieving a breakthrough increase in the product qualification rate.

[0019] By regulating the mass ratio of TiB2 to Fe powder to 1:1.2, the rolling temperature to 1080 - 1250 °C, and the cumulative reduction rate ≥ 80%, the core performance indicators such as the hardness, wear resistance, and corrosion resistance of the composite plate can be directionally optimized, meeting the customized requirements in fields such as aerospace and nuclear energy equipment, and significantly reducing the comprehensive production cost compared with similar processes. Description of the Drawings

[0020] Figure 1 It is a flowchart of a preparation process for a stainless steel - TiB2 gradient rolling composite plate based on the coordinated regulation of heterogeneous interfaces; Figure 2 It is a physical flowchart of the encapsulation structure in a preparation process for a stainless steel - TiB2 gradient rolling composite plate based on the coordinated regulation of heterogeneous interfaces; Figure 3 It is a physical picture of the whole after rolling in a preparation process for a stainless steel - TiB2 gradient rolling composite plate based on the coordinated regulation of heterogeneous interfaces; Figure 4 It is a physical picture of the cross-section after rolling in a preparation process for a stainless steel - TiB2 gradient rolling composite plate based on the coordinated regulation of heterogeneous interfaces; Figure 5 It is an image of the composite layer under a metallurgical microscope in a preparation process for a stainless steel - TiB2 gradient rolling composite plate based on the coordinated regulation of heterogeneous interfaces; Figure 6 It is an image of the composite layer under SEM in a preparation process for a stainless steel - TiB2 gradient rolling composite plate based on the coordinated regulation of heterogeneous interfaces. Detailed Embodiments

[0021] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0022] Please refer to Figure 1 - Figure 6 , the present invention provides a technical solution: a preparation process of a stainless steel-TiB2 gradient rolling composite plate based on heterogeneous interface synergistic regulation, including the following steps: Step 1. Matrix pretreatment: Select stainless steel nuts and plugs with specific component elements and sizes; Step 2. Powder pretreatment and filling: Ensure the purity and fluidity of the powder system through vacuum drying and mechanical ball milling mixing; Step 3. Encapsulation structure sealing: Achieve full-seal protection of the composite blank through argon arc welding and a high-temperature resistant adhesive layer; Step 4. Gradient heating and dynamic heat preservation: Precise temperature control to achieve matrix austenitization and interface atom activation.

[0023] Step 5. Multi-pass hot rolling composite: Roll along the direction parallel to the heterogeneous interface and perform intermittent furnace return to optimize interface bonding and tissue uniformity.

[0024] Specifically in Step 1, a 304 stainless steel tubular matrix (outer diameter 24 mm, inner diameter 16 mm) and a stainless steel plug of the phase diagram material (diameter M16, length 12 mm) are selected. The matrix composition (mass percentage): Cr (18% - 20%), Ni (8% - 10.5%), the balance is Fe and impurities, and the trace elements comply with GB / T20878.

[0025] Specifically in Step 2: TiB2 powder (0.5 - 2 μm) and 200 - 400 mesh Fe powder are mixed at a mass ratio of 1:1.2, filled into the matrix cavity after mechanical ball milling (filling density ≥ 95%), and vacuum dried to remove adsorbed water and volatiles to ensure fluidity.

[0026] Specifically in Step 3: The nut and the plug are mechanically engaged, and then welded. The welding parameters are: argon arc welding current 80 - 120 A, Ar purity ≥ 99.99%, weld gap ≤ 0.1 mm, weld oxygen content ≤ 0.3 wt%. The surface is coated with a high-temperature resistant inorganic adhesive (SINWE 1730℃ grade) with a coating thickness of 50 - 100 μm to prevent secondary oxidation during the rolling process.

[0027] Specifically in Step 4, the gradient heating and dynamic heat preservation, the specific process is as follows: 1. Heating curve: Gradually heat up at a rate of 5 °C / min to 1200 °C ± 20 °C, hold for 1 - 1.5 h, and the oxygen content in the furnace is ≤ 50 ppm; 2. Dynamic temperature control: During the holding stage, the temperature fluctuation is ≤ ±10 °C to avoid local overburning.

[0028] Specifically in Step 5: Rolling parameter setting: The reduction ratio of the first pass is ≤ 30%, the total reduction ratio is ≥ 85%, the rolling speed is 15 - 20 m / min, and the final rolling temperature is ≥ 800 °C; After each pass, heat in the furnace for holding (≥ 800 °C × 10 - 30 min), eliminate processing stress through dynamic recrystallization, roll along the direction parallel to the heterogeneous interface, fully activate the slip system and optimize the thermal stress distribution. Example

[0029] Production process of stainless steel - TiB2 composite plate (thickness 3 mm) Step 1. Substrate pretreatment: Select a 304 stainless steel tubular substrate (outer diameter 24 mm, inner diameter 16 mm, length 30 mm) and a 304 stainless steel plug (diameter M16, length 12 mm).

[0030] Step 2. Powder pretreatment and filling: Mix TiB2 powder (particle size 0.5 - 1 μm) and Fe powder (300 mesh) in a mass ratio of 1:1, and use a mechanical ball milling process (rotation speed 300 rpm - 400 rpm, ball milling time 2 - 4 h, ball - to - material ratio 10:1, wet milling with absolute ethanol) to process the mixed powder. After vacuum drying, fill it into the substrate cavity (filling density 96.3%).

[0031] Step 3. Sealing of the encapsulation structure: Mechanically engage the nut and the plug, and use argon arc welding (current 100 A, Ar purity 99.99%) to weld the stainless steel plug, with a weld gap of 0.08 mm, and coat the outer surface with aluminosilicate inorganic glue (thickness 80 μm, temperature resistance 1700 °C).

[0032] Step 4. Gradient heating: Heat up to 1200 °C at a rate of 5 °C / min in a box - type resistance furnace and hold for 1.2 h (oxygen content in the furnace ≤ 30 ppm) Step 5. Multi - pass rolling: Use a two - high hot rolling mill (roll diameter 90 mm), roll along the direction parallel to the heterogeneous interface, with an accumulated reduction ratio of 85%, heat in the furnace for holding (800 °C × 20 min) after each pass of rolling, and the final rolling thickness is 3.0 ± 0.1 mm. Example

[0033] Production process of stainless steel - TiB2 composite plate (thickness 5 mm) Step 1. Substrate pretreatment: Substrate pretreatment: Select a 304 stainless steel tubular substrate (outer diameter 24 mm, inner diameter 16 mm, length 30 mm) and a 304 stainless steel plug (diameter M16, length 12 mm).

[0034] Step 2. Powder pretreatment and filling: The TiB2 powder (particle size 1 - 2 μm) and Fe powder (200 mesh) are mixed at a mass ratio of 1:0.8, and the mixed powder is processed by mechanical ball milling. After vacuum drying, it is filled into the matrix cavity (filling density 95.8%).

[0035] Step 3. Encapsulation and sealing: The argon arc welding current is 80 A, and the thickness of the inorganic glue is 50 μm.

[0036] Gradient heating: Heat up to 1180 °C and hold for 1.5 h (oxygen content ≤ 50 ppm).

[0037] Step 4. Gradient heating: Heat up to 1180 °C and hold for 1.5 h (oxygen content ≤ 50 ppm).

[0038] Step 5. Multi-pass rolling: The cumulative reduction ratio is 82%, and the final rolling thickness is 5.0 ± 0.1 mm. Example

[0039] Production process of stainless steel - TiB2 composite plate (thickness 4 mm) Step 1. Matrix pretreatment: Select a 304 stainless steel tubular matrix (outer diameter 24 mm, inner diameter 16 mm, length 30 mm) and 304 stainless steel plugs (diameter M16, length 12 mm).

[0040] Step 2. Powder pretreatment and filling: The TiB2 powder (particle size 0.8 - 1.5 μm) and Fe powder (400 mesh) are mixed at a mass ratio of 1:1.2, and the mixed powder is processed by mechanical ball milling (rotation speed 300 rpm - 400 rpm, ball milling time 3 - 5 h, ball-to-material ratio 10:1, wet milling with absolute ethanol). After vacuum drying, it is filled into the matrix cavity (filling density 97.1%).

[0041] Step 3. Encapsulation and sealing: The argon arc welding current is 120 A, and the thickness of the inorganic glue is 100 μm.

[0042] Step 4. Gradient heating: Heat up to 1220 °C and hold for 1.0 h (oxygen content ≤ 20 ppm).

[0043] Step 5. Multi-pass rolling: The cumulative reduction ratio is 88%, and the final rolling thickness is 4.0 ± 0.1 mm.

[0044] Comparative Example 1: Traditional explosive cladding process Step 1. Matrix pretreatment: 304 stainless steel plate (thickness 3 mm); Step 2. Stacking of TiB2 powder: (Particle size 1 - 5 μm) Stacked directly without vacuum drying and screening, filling density 82%.

[0045] Step 3. Explosion cladding: The energy density of the explosive is 15 kJ / g, the explosion pressure is 8 GPa, and the thickness of the oxide layer at the composite interface is 4.8 μm.

[0046] Step 4. Hot rolling treatment: The reduction per pass is 50%, the rolling temperature is 1100 °C, there is no reheating and heat preservation, and the final rolling thickness is 3.0 ± 0.3 mm.

[0047] Comparative example 2: Unidirectional hot rolling process Step 1. Matrix pretreatment: Select a 304 stainless steel tubular matrix (outer diameter 24 mm, inner diameter 16 mm, length 30 mm) and a 304 stainless steel plug (diameter M16, length 12 mm).

[0048] Step 2. Powder pretreatment and filling: The TiB2 powder (particle size 1 - 3 μm) and Fe powder (100 - 500 mesh) are mixed in a ratio of 1:1, not mechanically ball-milled, and the filling density is 87%.

[0049] Step 3. Encapsulation and sealing: Manual arc welding (current 150 A, no shielding gas), the weld gap is 0.5 mm, and no high-temperature resistant adhesive layer is coated.

[0050] Step 4. Gradient heating: Heat up to 1150 °C (oxygen content in the furnace is 200 ppm), keep warm for 0.5 h, and the matrix is incompletely austenitized (the proportion of γ-Fe phase is 70%).

[0051] Step 5. Rolling: Unidirectional rolling (cumulative reduction ratio 65%), the rolling direction is random, the final rolling temperature is 750 °C, there is no reheating and heat preservation, and the final rolling thickness is 3.5 ± 0.5 mm.

[0052] Comparative example 3: Low-parameter rolling process Step 1. Matrix pretreatment: Select a 304 stainless steel tubular matrix (outer diameter 24 mm, inner diameter 16 mm, length 30 mm) and a 304 stainless steel plug (diameter M16, length 12 mm).

[0053] Step 2. Powder pretreatment and filling: The TiB2 powder (particle size 0.5 - 2 μm) and Fe powder (200 - 400 mesh) are mixed in a ratio of 1:1, filled into the matrix cavity after mechanical ball milling (filling density 91%).

[0054] Step 3. Encapsulation and sealing: TIG welding current 60 A (Ar purity 99.5%), the weld gap is 0.3 mm, and the thickness of the inorganic glue is 20 μm.

[0055] Step 4. Gradient heating: Heat up to 1050 °C (oxygen content in the furnace is 100 ppm), keep warm for 0.8 h, and the grain size of the matrix austenitization is 30 μm.

[0056] Step 5, rolling: cumulative reduction rate 60%, rolling temperature 900℃, reduction rate of each pass 40%, final rolling thickness 4.2±0.2mm.

[0057] Index Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Interface Shear Strength (MPa) 225 218 232 130 145 160 <![CDATA[TiB2 Breakage Rate (%)]]> 10 13 8 48 55 35 Oxide Layer Thickness (m) 1.5 1.8 1.2 4.8 6.2 3.5 Grain Size (m) 8-10 9-12 7-9 25-40 30-50 20-30 Thickness Tolerance (mm) ±0.1 ±0.1 ±0.1 ±0.3 ±0.5 ±0.2 Qualified Rate (%) 96 95 97 60 55 75 Table 1: Comparison of data between examples and comparative examples The experimental data are shown in Table 1 above.

[0058] To sum up: the present invention proposes a gradient temperature field-argon arc welding sealing coupling process, which achieves interface shear strength ≥ 210MPa, greatly reduces TiB2 crushing rate, reduces equipment cost, and has a qualified rate of more than 90% (explosive composite ≤ 70%). The localization rate of equipment is 100%, realizing the advancement, high efficiency and complete autonomy of the technology through ultra-low oxygen interface control, heterogeneous interface collaborative rolling (along the direction parallel to the heterogeneous interface, optimizing the plastic flow of particles) and non-vacuum multi-pass pressing (cumulative reduction rate ≥ 85%).

Claims

1. A stainless steel based on the coordinated regulation of heterogeneous interfaces The TiB2 gradient rolled composite plate preparation process is characterized by: The following steps are involved: Step 1: Substrate pretreatment: Select a 304 stainless steel tubular substrate and a 304 stainless steel plug of the same material; Step 2, powder pretreatment and filling: TiB2 powder and 200-400 mesh Fe powder are mixed in a mass ratio of 1:1-1.5, and mechanically ball milled using a planetary ball mill, using anhydrous ethanol as a wet grinding medium to prevent oxidation. After ball milling, the powder is vacuum dried and then filled into the matrix cavity; Step 3: Sealing the packaging structure: meshing the stainless steel plug with the nut, and then welding the stainless steel plug with the end face of the substrate by argon arc welding, and coating the outer surface with aluminosilicate-based high-temperature resistant inorganic glue after welding; Step 4: Gradient heating and dynamic temperature control: Place the package in a box-type resistance furnace, increase the temperature to 1200°C ± 20°C at a gradient of 5°C / min, and keep warm for 1-1.5h; Step 5, multi-pass rolling and organization control: longitudinal rolling is carried out using a two-roll hot rolling mill, the rolling direction is parallel to the heterogeneous interface, the initial pass reduction rate is ≤30%, and the cumulative reduction rate is ≥85%; after each rolling pass, the steel is returned to the furnace for insulation.

2. A process for preparing a stainless steel-TiB2 gradient rolled composite plate based on heterogeneous interface coordinated regulation as claimed in claim 1, characterized in that: In the step 1, the 304 stainless steel matrix composition is: Cr (18%-20%), Ni (8%-10.5%), and the remaining Fe and impurities.

3. A process for preparing a stainless steel-TiB2 gradient rolled composite plate based on heterogeneous interface coordinated regulation as claimed in claim 1, characterized in that: In the step 2, TiB2 powder and 200-400 mesh Fe powder are mixed in a mass ratio of 1:1.2, and mechanical ball milling is performed using a planetary ball mill at a speed of 200-300 rpm, a time of 2-4 hours, a ball-to-material ratio of 10:1, and the grinding balls are made of cemented carbide with a diameter of 5- 10mm, using anhydrous ethanol as the wet grinding medium to prevent oxidation, vacuum drying to remove adsorbed water and volatiles, and then filling density ≥95%.

4. A process for preparing a stainless steel-TiB2 gradient rolled composite plate based on coordinated regulation of heterogeneous interfaces according to claim 1, characterized in that: In step three, the stainless steel plug and the stainless steel nut are mechanically engaged, and the weld gap is ≤0.1 mm during the welding process.

5. The process for preparing a stainless steel-TiB2 gradient rolled composite plate based on heterogeneous interface coordinated regulation according to claim 1, characterized in that: In the step 4, the oxygen content in the furnace during the gradient heating stage is ≤50ppm, the temperature fluctuation during the insulation stage is ≤±10°C, and the austenitized grain size of the matrix is ​​≤50μm.

6. A process for preparing a stainless steel-TiB2 gradient rolled composite plate based on coordinated regulation of heterogeneous interfaces according to claim 1, characterized in that: In the step 5, the rolling direction is parallel to the long axis direction of the stainless steel matrix grains, and the roller linear speed is 15- 20m / min, final rolling temperature ≥800℃, final rolling thickness of plate 3-5mm.

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