First, what is 304 stainless steel17-4PH Stainless Steel Sheet/bar/pipe

304 stainless steel is a common material among stainless steels, with a density of 7.93 g/cm³; it is also called 18/8 stainless steel in the industry, which means it contains more than 18% chromium and more than 8% nickel; it is resistant to high temperatures of 800℃, has good processing performance and high toughness, and is widely used in the industrial and furniture decoration industries and the food and medical industries. However, it should be noted that the content index of food-grade 304 stainless steel is more stringent than that of ordinary 304 stainless steel. For example: the international definition of 304 stainless steel is that it mainly contains 18%-20% chromium and 8%-10% nickel, but food-grade 304 stainless steel contains 18% chromium and 8% nickel, allowing fluctuations within a certain range and limiting the content of various heavy metals. In other words, 304 stainless steel is not necessarily food-grade 304 stainless steel.

The common marking methods on the market include 06Cr19Ni10 and SUS304, of which 06Cr19Ni10 generally indicates national standard production, 304 generally indicates ASTM standard production, and SUS304 indicates Japanese standard production.

304 is a general-purpose stainless steel, which is widely used in the production of equipment and parts that require good comprehensive performance (corrosion resistance and formability). In order to maintain the inherent corrosion resistance of stainless steel, the steel must contain more than 18% chromium and more than 8% nickel. 304 stainless steel is a grade of stainless steel produced according to the American ASTM standard.

Second, the physical properties of 304 stainless steel410/S41000/ Stainless Steel

Tensile strength σb (MPa) ≥515-1035

Conditional yield strength σ0.2 (MPa) ≥205

Elongation δ5 (%) ≥40

Sectional shrinkage ψ (%)≥?

Hardness: ≤201HBW; ≤92HRB; ≤210HV

Density (20℃, g/cm³): 7.93

Melting point (℃): 1398~1454

Specific heat capacity (0~100℃, KJ·kg-1K-1): 0.50

Thermal conductivity (W·m-1·K-1): (100℃) 16.3, (500℃) 21.5

Linear expansion coefficient (10-6·K-1): (0~100℃) 17.2, (0~500℃) 18.4

Resistivity (20℃, 10-6Ω·m2/m): 0.73

Longitudinal elastic modulus (20℃, KN/mm2): 193

Third, the application scope of 304 stainless steel

Third, the application scope of 304 stainless steelN08800/810/NCF800

System description: 304 stainless steel is the most widely used chromium-nickel stainless steel. As a widely used steel, it has good corrosion resistance, heat resistance, low temperature strength and mechanical properties; it has good hot processing properties such as stamping and bending, and no heat treatment hardening phenomenon (use temperature -196℃～800℃). 304 stainless steel is corrosion-resistant in the atmosphere, but when used in industrial atmosphere or heavily polluted areas, it needs to be cleaned in time to avoid corrosion. It is suitable for food processing, storage and transportation, and has good processing performance and weldability. 304 stainless steel is also widely used in the manufacture of household goods (class 1 and 2 tableware, cabinets, indoor pipelines, water heaters, boilers, bathtubs), auto parts (windshield wipers, mufflers, molded products), medical equipment, building materials, chemical equipment, agricultural equipment, ship parts, etc. Among them, 304 stainless steel with strictly controlled content can also be called food-grade 304 stainless steel

Most of the use requirements are to maintain the original appearance of the building for a long time. When determining the type of stainless steel to be selected, the main considerations are the required aesthetic standards, the corrosiveness of the local atmosphere, and the cleaning system to be adopted. However, other applications increasingly seek only structural integrity or impermeability. For example, the roofs and side walls of industrial buildings. In these applications, the owner's construction cost may be more important than aesthetics, and the surface may not be very clean. 304 stainless steel works quite well in dry indoor environments. However, in rural and urban areas, it needs to be cleaned frequently to maintain its appearance outdoors. In heavily polluted industrial and coastal areas, the surface will be very dirty and even rust.

But to achieve the aesthetic effect in the outdoor environment, nickel-containing stainless steel is required. Therefore, 304 stainless steel is widely used in curtain walls, side walls, roofs and other construction purposes, but 316 stainless steel is best used in severely corrosive industrial or marine atmospheres. Stainless steel sliding doors, people have fully realized the advantages of using stainless steel in structural applications. There are several design criteria that include 304 and 316 stainless steel. Because the "duplex" stainless steel 2205 has integrated good atmospheric corrosion resistance with high tensile strength and elastic strength, this steel is also included in the European criteria. Product shape Stainless steel is actually manufactured in all standard metal shapes and sizes, and there are also many special shapes. The most commonly used products are made of thin plates and strips, and medium and thick plates are also used to produce special products, such as hot-rolled structural steel and extruded structural steel. There are also round, oval, square, rectangular and hexagonal welded or seamless steel pipes and other forms of products, including profiles, bars, wires and castings.

Fourth, the processing method of 304 stainless steelS32202/1.4062 Duplex Stainless Steel

Etching method

The etching method is to use screen printing acid-resistant protective film on the surface of stainless steel, and then etch it with ferrous chloride liquid to form an artistic pattern.

Spraying method

The spraying method is to spray colorant particles after screen printing to form a pear-like surface and an artistic pattern.

Process

The process of the spraying art processing method of stainless steel products is: stainless steel products → screen printing → etching → alkali treatment → screen printing → oxidation coloring → alkali treatment → finished product.

The process of etching art processing method of stainless steel products is: stainless steel products → screen printing → etching → alkali treatment → oxidation coloring → finished product.

The chemical coloring method of stainless steel does not use pigments and dyes, but soaks the stainless steel in a heated concentrated chromium sulfate solution for chemical coloring, which is characterized by good food resistance. The ink used in this processing method must have very strong acid resistance, and generally uses UV vulcanized ink with special properties that is compatible with the processing process.

Stamping processing

For stainless steel products, especially stainless steel strips, the most primitive processing method of the factory is often to use a punch press to stamp products. Stamping includes two methods: straight punching and stretching. Generally, for hardness less than 1/2, stretching and bending are used, and for hardness higher than 1/2, straight punching is used.

Causes of rust