Stainless steel is an alloy of chromium and nickel. Sometimes, it is referred as SUS, an acronym from the Japanese Industrial Standards (JIS). Generally SUS is Steel Use Stainless.
Also known as A2 steel, 304 stainless steel has excellent resistance to a wide range of atmospheric environments and many corrosive media. It is subject to pitting and crevice corrosion in warm chloride environments and to stress corrosion cracking above about 60°C. It is considered resistant to potable water with up to about 200 mg/L chlorides at ambient temperatures, reducing to about 150 mg/L at 60 °C.
304 stainless steel is also very sensitive at room temperature to the thiosulfate anions released by the oxidation of pyrite (as encountered in acid mine drainage) and can undergo severe pitting corrosion problems when in close contact with pyrite- or sulfide-rich clay materials exposed to oxidation.
For more severe corrosion conditions, when 304 stainless steel is too sensitive to pitting or stress corrosion cracking.
MATERIAL COMPOSITION
| DESCRIPTION | 304S | 304L | 304H |
| Density (kg/m3) | 8000 | ||
| Tensile Strength (Mpa) | 515~520 | 485~607 | 515~720 |
| Yield Strength (Mpa) | 205 | 170 | 205 |
| Poisson’s ratio(min) | 0.27-0.30 | ||
| Elongation A5(%) | 40 | 40 | 40 |
| Proof stress .02%(MPa) | 210 | 200 | 210 |
| Brinell Hardness (HB) | 92 | 92 | 92 |
| Chemical Composition (%age) | |||
| Carbon (C) | ≤ 0.08 | ≤ 0.03 | ≤ 0.040~0.10 |
| Silicon (Si) | ≤1.00 | ≤ 0.75 | ≤ 0.75 |
| Manganese (Mn) | ≤ 2.00 | ≤ 2.00 | ≤ 2.00 |
| Phosphorous (P) | ≤ 0.045 | ≤ 0.045 | ≤ 0.045 |
| Sulphur (S) | ≤0.030 | ≤0.030 | ≤0.030 |
| Nickel (Ni) | ≤ 8~10.50 | ≤ 8~10.50 | ≤ 8~10.50 |
| Chromium (Cr) | ≤ 18.00~20.00 | ≤ 18.00~20.00 | ≤ 18.00~20.00 |
| Typical physical properties | |||
| Density | 8.00g/cm3 | ||
| Melting Point | 1450C | ||
| Young’s Modulus (GPa) | 190 | ||
| Electrical resitivity | 0.072 x 10-6Um | ||
| Thermal conductivity | 16.2W/m.K | ||
| Thermal expansion | 17.2 x 10.6/K | ||
| Equivalent Standards | |||
| DINX5CrNi1810 | DIN | ||
| AISI 304 | AISI | ||
| X4CrNi18-10 | EN | ||
| BS304S31 | BS | ||
| 11 | ISO |