Stainless Steel Grade 310

Chemical Composition

(AS1449 / ASTM A240 - Flat Products)

Mechanical Properties

(AS1449 / ASTM A240 - Flat Products)

Description

These grades contain 25% chromium and 20% nickel, making them highly resistant to oxidation and corrosion. Grade 310S is a lower carbon version, less prone to embrittlement and sensitisation in service.

The high chromium and medium nickel content make these steels capable for applications in reducing sulphur atmospheres containing H2S. They are widely used in moderately carburising atmospheres, as encountered in petrochemical environments. For more severe carburising atmospheres other heat resisting alloys should be selected. Grade 310 is not recommended for frequent liquid quenching as it suffers from thermal shock. The grade is often used in cryogenic applications, due to its toughness and low magnetic permeability.

In common with other austenitic stainless steels, these grades cannot be hardened by heat treatment. They can be hardened by cold work, but this is rarely practiced.

Availability

Austral Wright Metals can supply these grades as plate, sheet and strip, bar and rod, seamless tube and pipe, welded tube and pipe, forgings and forging billet, tube and pipe fittings, wire.

Corrosion Resistance

Grade 310/310S is generally not used for corrosive liquid service, although the high chromium and nickel content give corrosion resistance superior to grade 304. The alloy does not contain molybdenum, so pitting resistance is quite poor. Grade 310/310S will be sensitised to intergranular corrosion after service at temperatures in range 550 - 800°C. Chloride stress corrosion cracking may take place in corrosive liquids containing chlorides at temperatures exceeding 100°C.

Physical Properties

(Typical, annealed)

Heat Resistance

Grades 310/310S have good resistance to oxidation in intermittent service in air up to 1035°C and 1050°C in continuous service. The grades are resistant to oxidation, sulphidation and carburisation.

Pressure Vessels

AS1210, Pressure Vessels, allows the use of grade 310 up to 800°C.

Fabrication

Grades 310/310S are forged in the temperature range 975 - 1175°C. Heavy work is carried out down to 1050°C and a light finish is applied to the bottom of the range. After forging annealing is recommended to relieve all stresses from the forging process. The alloys can be readily cold formed by standard methods and equipment.

Machinability

Grades 310/310S are similar in machinability to type 304. Work hardening can be a problem and it is normal to remove the work hardened layer by using slow speeds and heavy cuts, with sharp tools and good lubrication. Powerful machines and heavy, rigid tools are used.

Weldability

Grades 310/310S are welded with matching electrodes and filler metals. The alloys are readily welded by SMAW (manual), GMAW (MIG), GTAW (TIG) and SAW. Electrodes to AWS A5.4 E310-XX and A 5.22 E310T-X, and filler metal AWS A5.9 ER310 are used. Argon is shielding gas.

Preheat and post heat are not required, but for corrosion service in liquids full post weld solution annealing treatment is essential.

Pickling and passivation of the surface to remove high temperature oxides are essential to restore full aqueous corrosion resistance after welding. This treatment is not required for high temperature service, but welding slag should be thoroughly removed.

Heat Treatment

Type 310/310S are solution annealed by heating to temperature range 1040 - 1065°C, holding at temperature until thoroughly soaked, then water quenching.

Effect of Exposure at 480 - 650º on Room Temperature Toughness and Hardness

Mechanical Properties at Cryogenic Temperatures