Features
Alloy 310 (UNS S31000) is an austenitic stainless steel developed for use in high temperature corrosion resistant applications. The alloy resists oxidation up to 2010oF (1100oC) under mildly cyclic conditions.
Because of its high chromium and moderate nickel content, Alloy 310 is resistant to sulfidation and can also be used in moderately carburizing atmospheres.
The more severe carburizing atmospheres of thermal process equipment usually require nickel alloys such as 330 (UNS N08330). Alloy 310 can be utilized in slightly oxidizing, nitriding, cementing and thermal cycling applications, albeit, the maximum service temperature must be reduced. Alloy 310 also finds usage in cryogenic applications with low magnetic permeability and toughness down to -450oF (-268oC). When heated between 1202 – 1742oF (650 – 950oC) the alloy is subject to sigma phase precipitation. A solution annealing treatment at 2012 – 2102oF (1100 – 1150oC) will restore a degree of toughness.
Chemical Composition (%)
| Element | Minimum percentage | Maximum percentage |
| C | – | 0.08 |
| Si | – | 1.5 |
| Mn | – | 2.0 |
| P | – | 0.045 |
| S | – | 0.03 |
| Cr | 24 | 26 |
| Ni | 19 | 22 |
Surface
Through different processing methods of cold rolling and surface reprocessing after rolling, the surface finish of 310S stainless steel strips can have different types. The surface processing of stainless steel strips have NO.1, 2B, NO. 4, HL, NO. 8, BA and other surface.
NO.1 surface refers to the surface obtained by heat treatment and pickling after hot rolling of the stainless steel strip. It is to remove the black oxide scale produced during hot rolling and heat treatment by pickling or similar treatment methods. This is NO.1 surface processing. The No.1 surface is silvery white and matt. Mainly used in heat-resistant and corrosion-resistant industries that do not require surface gloss, such as alcohol industry, chemical industry and large containers.
The surface of 2B is different from the 2D surface in that it is smoothed with a smooth roller, so it is brighter than the 2D surface. The surface roughness Ra value measured by the instrument is 0.1～0.5μm, which is the most common processing type. This kind of stainless steel strip surface is the most versatile, suitable for general purposes, which is widely used in the chemical, paper, petroleum, medical and other industries, and can also be used as a building curtain wall.
The surface of No. 4 is a fine polished surface finish that is brighter than the surface of NO.3. It is also obtained by polishing the stainless steel cold-rolled stainless steel strip with 2D or 2B surface as the base and polishing with abrasive belt with a grain size of 150-180# Machined surface. The surface roughness Ra value measured by the instrument is 0.2～1.5μm. NO.4 surface is widely used in restaurant and kitchen equipment, medical equipment, architectural decoration, containers, etc.
HL surface is commonly called hairline finish. Japanese JIS standard stipulates that 150-240# abrasive belt is used to polish the continuous hairline-like abrasive surface obtained. In China’s GB3280 standard, the regulations are rather vague. HL surface finish is mostly used for building decoration such as elevators, escalators, and facades.
BA is the surface obtained by bright heat treatment after cold rolling. Bright heat treatment is annealing under a protective atmosphere that guarantees that the surface is not oxidized to preserve the gloss of the cold-rolled surface, and then use a high-precision smoothing roll for light leveling to improve the surface brightness. This surface is close to a mirror finish, and the surface roughness Ra value measured by the instrument is 0.05-0.1μm. BA surface has a wide range of uses and can be used as kitchen utensils, household appliances, medical equipment, auto parts and decorations.
NO.8 is a mirror-finished surface with the highest reflectivity without abrasive grains. The stainless steel deep processing industry also calls as 8K plates. Generally, BA materials are used as raw materials for mirror finishing only through grinding and polishing. After mirror finishing, the surface is artistic, so it is mostly used in building entrance decoration and interior decoration.
