Stainless steel has become an ideal material for modern industry and life with its excellent corrosion resistance, strength and aesthetics. It resists corrosion by forming a dense chromium oxide protective film on the surface, making it durable for everything from kitchenware to chemical equipment. It can achieve different strength characteristics by adjusting its composition, meeting diverse needs from construction to medical treatment. It also has a metallic texture and modern aesthetics, and is a model of the perfect combination of function and design.

1、Definition of Stainless Steel

Iron-based alloys containing more than 10.5% chromium are called stainless steel. The term "stainless steel" is a general designation for both rust-resistant and acid-resistant steels. In the fields of metallurgy and materials science, a series of iron-based alloys with a chromium content exceeding 10.5%, primarily characterized by corrosion and rust resistance, are referred to as stainless steel.

Generally speaking, steels that are stainless and corrosion-resistant in less corrosive environments such as the atmosphere, water vapor, and fresh water are called stainless steels; and steels that are corrosion-resistant in highly corrosive media such as acids, alkalis, and salts are called acid-resistant steels. These two types of steel have different corrosion resistance due to their different compositions - the former has a lower degree of alloying and is usually not acid-resistant; the latter has a higher degree of alloying and has both acid resistance and stainless properties.

The most basic characteristics of stainless steel are its rust resistance in the atmosphere and its corrosion resistance in various liquid media. This characteristic is directly related to the chromium content in the steel: the presence of chromium forms an invisible oxide film on the surface of the steel, which can prevent oxidation and "passivate" the material, thereby making it corrosion-resistant. Adding other elements such as nickel and molybdenum can further improve corrosion resistance, strength, and high temperature resistance.

Corrosion resistance increases with the increase of chromium content. When the chromium content reaches more than 10.5%, the performance of the steel will undergo a qualitative change - from easy to rust to stainless, and from non-corrosion-resistant to corrosion-resistant. After exceeding this critical value, as the chromium content continues to increase, its anti-rust ability and corrosion resistance will continue to improve.

Steels that resist rust and corrosion in weakly corrosive environments such as air, water vapor, and freshwater are generally called "stainless steel," while those resistant to highly corrosive environments such as acids, alkalis, and salts are termed "acid-resistant steel." Differences in composition between these two categories result in varying corrosion resistance—the former has lower alloy content and typically lacks acid resistance, while the latter, with higher alloy content, exhibits both acid and rust resistance.

2、Composition of Stainless Steel

The core alloying element of stainless steel is chromium (Cr), and its content directly affects the corrosion resistance of the material. Experiments have shown that the chromium content in steel reaches more than 10.5% to have basic corrosion resistance, so this is the minimum standard requirement for the chromium content of stainless steel.

In addition to chromium, various alloying elements are added to stainless steel to optimize its performance, including nickel (Ni), titanium (Ti), manganese (Mn), nitrogen (N), niobium (Nb), molybdenum (Mo), silicon (Si) and copper (Cu). In particular, carbon can significantly reduce the corrosion resistance of stainless steel, so the carbon content in industrial stainless steel is usually strictly controlled, generally below 1.2%. Some ultra-low carbon steel grades (such as 00Cr12) have a carbon content of less than 0.03%.

The effect of chromium on the performance of stainless steel is mainly reflected in three aspects:

Passivation: Chromium is the main element in austenitic stainless steel. It can promote the formation of a stable passivation film on the surface of the material and improve corrosion resistance.

Effect on microstructure: Chromium, as a strong ferrite forming element, can reduce the austenite phase field. Too high chromium content will lead to the precipitation of delta ferrite.

Composition balance: When the carbon content of chromium-nickel austenitic stainless steel is 0.1%, the chromium content is 18%, and the nickel content is 8%, the most stable single-phase austenite structure can be obtained. The research results lay a theoretical foundation for 18Cr-8Ni stainless steel as a classic formula.

3、Types of Stainless Steel

Stainless Steel Plate

By surface finish: Mirror-finish plates, brushed plates, embossed plates, 2B/BA finish plates

By process: Cold-rolled plates, hot-rolled plates, precision strips

Stainless Steel Pipe/Tube

By manufacturing process: Seamless tubes, welded tubes (longitudinal welded, spiral welded)

By application: Structural pipes, fluid transport pipes, sanitary pipes, heat exchanger tubes

Stainless Steel Coil

By surface finish: 2B finish coils, BA (Bright Annealed) coils, No.4 brushed coils

By thickness: Thin gauge coils (0.3-3.0mm), thick gauge coils (3.0-12.7mm)

By application: Kitchenware coils, decorative coils, industrial coils

Stainless Steel Profiles

By shape: Angle steel, channel steel, I-beams, flat bars

By hollow sections: Square tubes, rectangular tubes, round tubes

Stainless Steel Bar & Wire

Bar types: Round bars, square bars, hexagon bars, bright bars

Wire types: Spring wire, welding wire, weaving wire, rope wire

 Stainless Steel Fittings & Components

Pipe fittings: Flanges, elbows, tees, reducers

Fasteners: Bolts, nuts, screws, washers

Special Stainless Steel Products

Precision products: Foils, ultra-thin strips, precision tubes

Composite materials: Clad plates, bimetal sheets

Custom parts: Stamped components, machined parts, castings