AISI 310S Equal Angles

AISI 310S equal angle is a rolled angle section in an austenitic stainless steel made for parts that work at high temperature. The grade carries more chromium and more nickel than the common austenitic grades: the chromium forms the oxide film that resists scaling in hot air and combustion gases, and the nickel keeps the structure austenitic, so the section does not change structure as it heats and cools. AISI 309S, the grade one step below, holds less of both elements and scales at a lower temperature. AISI 310 has the same chromium and nickel range but allows carbon up to 0.25 percent, while 310S caps carbon at 0.08 percent, so less chromium carbide forms at the grain boundaries when the angle is welded.

The angle is supplied hot rolled, annealed and pickled: annealing heats the steel until the carbides return into the metal, and the acid bath takes off the scale that rolling leaves. Annealed 310S is non-magnetic and takes no hardening from heat treatment; cold work is the only route to more strength. The minima of ASTM A276, which covers hot rolled shapes as well as bars, are 515 MPa tensile and 205 MPa yield. The grade work hardens quickly, so sawing and drilling ask for sharp tools, a firm feed and lower speeds than carbon steel. It is welded with a matching 310 filler and without preheat. Equal angle in this grade is fabricated into furnace and kiln framework, hearth and tray supports, heat treatment baskets and fixtures, and brackets in flue gas ducting.

Composition limits in weight percent are carbon 0.08 maximum, manganese 2.0 maximum, sulphur 0.03 maximum, phosphorus 0.045 maximum, silicon 1.5 maximum, chromium 24.0 to 26.0 and nickel 19.0 to 22.0.