As an indispensable basic material in modern industry and people's livelihood, stainless steel plates have penetrated into all aspects of production and life with their excellent corrosion resistance, mechanical properties and processing adaptability. From food processing equipment to marine engineering structures, from medical equipment to architectural decoration, the performance differences and reasonable selection of stainless steel plates directly affect product quality and service life. This article will systematically sort out the classification system, core characteristics, purchase points and typical applications of stainless steel plates, providing a reference for industry selection and daily cognition.
1. Classification system of stainless steel plates

The classification dimensions of stainless steel plates are diverse. The core can be divided according to organizational structure, processing technology and material series. Different classifications correspond to differentiated performance and uses, forming a complete product matrix.

(1) Classification by organizational structure

The organizational structure is determined by the alloy composition ratio and is the core source of performance differences of stainless steel plates. It is mainly divided into five categories:

1. Austenitic stainless steel plate: contains about 18% chromium and 8%-10% nickel. The typical representative is 304 stainless steel plate (18%-20% chromium, 8%-10.5% nickel). It has good plasticity, toughness and corrosion resistance, is non-magnetic or weakly magnetic, and easily forms a dense passivation film on the surface to resist corrosion. It is widely used in food processing, medical equipment, building decoration and other fields.

2. Martensitic stainless steel plate: chromium is the main alloy element, with a carbon content of 0.1%-1.0% and a chromium content of 11.5%-18%, such as model 410. It has high strength and hardness, but weak toughness and corrosion resistance. Its mechanical properties can be significantly improved after heat treatment. It is often used in scenes with high hardness requirements such as cutting tools, mechanical parts, and valves.

3. Ferritic stainless steel plate: chromium content 11%-30%, basically no nickel, typical such as 430 stainless steel plate (chromium 16%-18%). It has good oxidation corrosion resistance and excellent thermal conductivity, but its strength and processing performance are slightly inferior to austenitic stainless steel. It is suitable for building decorative strips, automobile exhaust pipes, microwave oven casings, etc.

4. Duplex stainless steel plate: It has a two-phase structure of austenite and ferrite, with a chromium content of 20%-30% and a nickel content of 3%-8%, such as model 2205. It combines the advantages of two types of steel, with good toughness, high strength, and outstanding resistance to stress corrosion cracking. It is mainly used in high-end fields such as chemical industry, petroleum, and ocean engineering.

5. Precipitation hardening stainless steel plate: Add copper, niobium, titanium and other elements, and form a precipitation hardening phase after heat treatment, such as 17-4PH (630 model). High strength and hardness can be obtained through heat treatment while maintaining a certain degree of corrosion resistance. It is used in aerospace, high-performance mechanical shaft parts and other scenarios.

(2) Classification by processing technology

The processing technology directly affects the surface quality, dimensional accuracy and mechanical properties of stainless steel plates, and is mainly divided into two categories: cold rolling and hot rolling:

1. Cold-rolled stainless steel plate: hot-rolled slab is rolled at room temperature, and the thickness is usually less than 3mm. It has a smooth surface, high dimensional accuracy, good flatness, and excellent ductility. It can be used for high-precision processing such as stamping and bending. However, it requires annealing to restore plasticity after work hardening. It is suitable for scenes such as electronic equipment casings, elevator car interiors, and automotive interior parts that require high appearance and precision.

2. Hot-rolled stainless steel plate: The steel billet is heated at high temperature and then rolled. The thickness is usually more than 3mm. The surface is relatively rough, the price is lower, the structure is uniform, the comprehensive mechanical properties are good, and the strength and toughness are excellent. It is often used in load-bearing structural parts such as steel structure frames, pressure vessels, and bridges.

(3) Classification by material series

The material series is divided according to alloy ratio rules and is a common reference for market selection. The core includes three series:

1. 200 series: Using manganese instead of nickel to reduce costs and have poor anti-corrosion performance, such as 201 and 202 models, suitable for indoor decoration, low-end kitchenware and other scenes that require low corrosion resistance.

2. 300 series: Chromium-nickel austenitic stainless steel with the best comprehensive performance, such as 304 and 316 models, which are used in many fields such as food processing, chemical equipment, and medical equipment. They are currently the most widely used series.

3. 400 series: Containing ferritic and martensitic stainless steel, without manganese components, such as 409, 410, and 430 models, which can partially replace 304 and are used in automobile exhaust systems, architectural decoration, etc.

2. Comparison of core model features and purchasing tips

There are many types of stainless steel plates on the market, and the quality varies. Mastering the characteristics and identification methods of core models is the key to avoiding procurement traps.

(1) Comparison of core features of mainstream models

304, 316, and 310S are the most representative models, and their performance differences determine the application boundaries:

1. 304 stainless steel plate: The king of cost performance, with up to standard chromium and nickel content (chromium 18%-20%, nickel 8%-10.5%), excellent corrosion resistance, and suitable for most normal temperature environments, such as kitchen utensils, home appliance casings, building water pipes, etc. You need to be wary of low-priced and low-quality products that are passed off as inferior by reducing the nickel content (6%-7%), making them prone to rust.

2. 316 stainless steel plate: Adding 2.5% molybdenum element to 304, its resistance to chloride ion corrosion is greatly improved. It is suitable for coastal areas, chemical equipment, marine engineering and other scenarios. The price is 30%-50% higher than 304. The low-carbon version 316L (carbon content ≤0.03%) has stronger resistance to intergranular corrosion and is suitable for welding and high-temperature environments.

3. 310S stainless steel plate: high-alloy austenitic stainless steel, chromium 24%-26%, nickel 19%-22%, excellent high temperature resistance, continuous use temperature up to 1150°C, resistant to sulfide and chloride corrosion, suitable for petrochemical reactors, heat treatment furnaces, aircraft engine tail nozzles and other extreme environments.

(2) Key points for purchasing quality control

1. Composition and certification verification: Suppliers are required to provide third-party spectral analysis reports and material certificates (MTC) to check the content of core elements such as chromium, nickel, and molybdenum to ensure compliance with international standards such as ASTM, JIS, and GB. Food grade applications require additional verification of FDA or GB 4806.9-2016 certification.

2. Surface and dimensional inspection: The surface of high-quality plates should be free of scratches, pits, and color differences, and the reflection should be uniform when illuminated by strong light from the side; the thickness tolerance must meet the requirements. Products with a precision tolerance of ±0.05mm should be preferred for precision machining parts, and the edges should be smooth and free of burrs.

3. Performance testing and verification: The mechanical properties must meet the tensile strength ≥515MPa, yield strength ≥205MPa, and elongation ≥40% (thin materials ≥35%); corrosion resistance can be verified through salt spray test (no red rust for 72 hours) or simulated use environment immersion.

4. Simple identification method: magnetic test (304/316 has no magnetism or weak magnetism, strong magnetism may be 200 series); potion test (201 turns red quickly, 304/316 changes color slightly or does not change color); spark observation (304 sparks have short straight lines and few bifurcations, 200 series sparks are intensive and have many bifurcations).

3. Typical application areas of stainless steel plates

The application scenarios of stainless steel plates continue to expand with performance upgrades, from people's livelihood fields to high-end industries, forming a diversified application pattern.

(1) People’s livelihood and construction fields

Relying on aesthetics and corrosion resistance, stainless steel plates are widely used in architectural decoration and daily life. Cold-rolled 304 plates are used in elevator cars, interior decorative strips, and home appliance casings; 430 plates are suitable for microwave oven casings and car accessories; building steel structure frames mostly use hot-rolled stainless steel plates, taking into account both strength and cost.

(2) Industrial manufacturing field

Different industries have significantly different performance requirements: in the chemical industry, 2205 dual-phase steel and 316L plates are used to manufacture pipelines and storage tanks to resist acid and alkali corrosion; in the heat treatment industry, 310S plates are used to make furnace transfer rollers, which can withstand high temperatures of 1050°C; in the metallurgical industry, 310S is used as the transition layer of the continuous casting machine crystallizer to extend the life of the equipment.

(3) High-end special fields

In extreme environments, the high performance of stainless steel plates can be fully utilized: in the aerospace field, 310S is used to make engine tail nozzle regulators, which remain stable under 650°C gas erosion; in marine engineering, 310S and 316 plates are used to make underwater Christmas tree parts to resist high-salt corrosion in deep sea; in the medical device field, 304/316L plates are used to make surgical instruments and sterilizer chambers, which meet health standards and corrosion resistance requirements.

(4) Emerging application areas

With the development of technology, the application of stainless steel plates in the field of new energy has gradually expanded. 310S plate has been included in the research and development of hydrogen energy storage and transportation equipment due to its excellent resistance to hydrogen embrittlement; through laser cladding technology, 310S powder can repair gas turbine blades, helping energy conservation and environmental protection.

4. Maintenance and industry development trends

Proper maintenance can extend the service life of stainless steel plates: daily cleaning with neutral detergent is required to avoid scratching with hard objects to damage the passivation film. In coastal areas, surface salts need to be wiped off in time and away from strong acid and alkali substances.

At the industry level, stainless steel plates are developing in the direction of high performance, refinement, and greenness. Through micro-alloying improvement (adding rare earth elements), the adaptability to extreme environments is improved; precision cold rolling technology is upgraded to meet the high-precision needs of electronics, medical and other fields; recycling technology is improved to reduce production energy consumption and promote sustainable development.

As a multifunctional material, the development of stainless steel plates is closely related to industrial progress and improvement of people's livelihood. In the future, as the demand in emerging fields is released, its performance and application boundaries will continue to expand, providing support for high-quality development in various industries.