There are three differences between 304 stainless steel and 202 stainless steel:

First, the physical properties of the two are different:

1. The physical properties of 202 stainless steel: tensile strength is 520MPa, yield strength is 275MPa, elongation is 55~60%, elastic modulus is 203000MPa, hardness requirement (Brinnell hardness) HRB<183N/mm2 (MPa).

2. Physical properties of 304 stainless steel plate: tensile strength ≥515~1035MPa, conditional yield strength ≥205MPa, elongation ≥40%, hardness ≤201HBW, density 7.93g/cm3, melting point 1398~1454℃, longitudinal elasticity The modulus is 193KN/mm2.

Outlook for the month: The logic of resonance is still there, with equal emphasis on opportunities and risks. The excellent performance of the steel industry in April was due to the large decline in the previous period and the continuation of the boom. The rebound in steel prices and the recovery of gross profits have further consolidated the foundation for the industry's rebound. There is no need to worry too much. The recovery of industry fundamentals has not been reflected in the stock price performance in the same proportion. In May

Heat resistance refers to the ability of stainless steel to maintain its excellent physical and mechanical properties under high temperatures. Effect of Carbon: Carbon is strongly formed and stable in austenitic stainless steels.

Second, the two have different uses:

1. Use of 202 stainless steel: producing high-quality materials for various watch cases, watch strap bottom covers, etc. Mainly used to make decorative pipes, industrial pipes, and some shallow drawn products.

2. Uses of 304 stainless steel: It is widely used in the industrial and furniture decoration industries and the food and medical industries. It is also used to make equipment and parts that require good comprehensive performance (corrosion resistance and formability).

In austenitic stainless steel, carbon is often regarded as a harmful element. This is mainly because under some conditions in the corrosion resistance of stainless steel, carbon can form high-chromium Cr23C6 carbon compounds with chromium in the steel, resulting in local chromium loss. Dilution reduces the corrosion resistance of steel, especially intergranular corrosion resistance.

Third, the characteristics of the two are different:

1. Characteristics of 202 stainless steel: It has certain acid and alkali resistance, high density, no bubbles and no pinholes when polished.

2. Characteristics of 304 stainless steel plate: high temperature resistance of 800°C, good processing performance and high toughness. Most of the newly developed chromium-nickel austenitic stainless steels since the 1960s have carbon content less than or ultra-low carbon. It can be known that as the carbon content decreases, the intergranular corrosion sensitivity of steel decreases. When the carbon content is lower than that, it will have obvious corrosion resistance. Some experiments also pointed out that carbon will also increase the pitting corrosion tendency of chromium austenitic stainless steel.