153 MA Forgings (EN 1.4818 / UNS S30415): Rolled Rings, Flanges, Bars and Discs

Equivalent designations

Buyers often move to 153 MA from 309S / 1.4833 when creep deformation is the failure mode rather than scaling. Outokumpu records a bell furnace inner cover running at 770 to 850 °C in 92 percent nitrogen with 8 percent hydrogen, where 309S was replaced by 153 MA to obtain the creep strength required and an oxide layer that stays adherent through temperature cycling.

Chemical composition

The cerium, nitrogen and silicon additions are what separate this grade from a plain 18/9 austenitic. They give oxide scale stability, resistance to sigma phase precipitation and strength at temperature, while the austenitic matrix keeps its toughness down to cryogenic temperatures.

Mechanical properties at 20 °C

Physical properties at 20 °C

Service temperature and behaviour at temperature

Published figures are close but not identical, so both are given here. The Outokumpu Therma comparison table lists a maximum service temperature in dry air of 1050 °C, 1920 °F, to EN 10095, and the same brochure recommends the grade for use up to 1000 °C, 1830 °F. Metalcor states resistance to scaling up to 1000 °C. AZoM puts optimal performance at 600 to 950 °C. For quotation purposes we work to 1000 °C as the practical continuous ceiling in air, and we ask for the atmosphere, the thermal cycle and the working stress before recommending a section thickness.

In the Outokumpu ranking of the Therma range, 153 MA takes four stars out of five for creep rupture strength and four for structural stability, the latter above 253 MA, because 153 MA has excellent resistance to the embrittlement that affects several austenitic heat resistant grades during continuous operation at 600 to 850 °C. On the 100000 hour relative creep rupture curve it sits below 253 MA and above 321H / 1.4878, 309S and 310S / 1.4845 over most of the range.

Atmosphere limit The Metalcor datasheet for 1.4818 records low resistance to oxidizing sulphurous gases. Outokumpu notes more generally that low nickel grades resist sulphur induced high temperature corrosion better than higher nickel grades, and that ferritic grades such as 1.4742 are preferred for sulphur bearing atmospheres at low tensile load. If your process gas carries sulphur, state it on the enquiry and we will review the grade with you before quoting.

Applications for 153 MA forgings

This is a heat resistant grade, so the duty is furnace, heat treatment and high temperature process equipment rather than seawater or acid service. Outokumpu lists recuperators, conveyor belts, expansion bellows, power generation components, cyclone dip tubes, bell and muffle furnaces, automotive components, tube shields, valves and flanges, heat treatment trays and dampers. AZoM adds cement plant equipment, hot air dryers, superheater tubes, fluidised beds, waste combustion and exhaust gas preheating.

In the shapes we forge, that means seamless rolled rings for furnace rolls, kiln and recuperator assemblies; forged flanges and valve bodies for hot gas and radiant tube duty; forged tube sheets for high temperature heat exchangers and recuperators; forged discs, blanks and bushings for heat treatment fixtures and dampers; forged shafts, spindles and round bars for furnace and conveyor mechanisms; and forged nozzles and sleeves for burners and hot gas ducting. Where a part runs continuously above 1000 °C we normally offer 253 MA / 1.4835 / S30815 instead.

Forging and heat treatment

Melting route is electric arc furnace with VOD refining, with ESR available where a tighter inclusion rating or better transverse ductility is called for. Hot working is carried out in the 900 to 1150 °C window published for this grade and followed by rapid cooling. The finished forging is solution annealed at 1020 to 1100 °C and quenched, which restores the austenitic structure and returns the nitrogen and cerium contributions to solution. Rings are produced on a radial axial ring rolling mill to give circumferential grain flow. Shafts, blocks and discs are open die forged with the forging ratio recorded on the route card.

For fabrication on your side, 153 MA solidifies in a ferritic mode, so weldability is comparable with the standard chromium nickel austenitics. Outokumpu recommends 21 10 N wire for MAG welding and notes that a pulsed power source may be needed for good weldability. Metalcor lists 1.4835 as a suitable filler. Submerged arc, plasma arc, flux cored and shielded metal arc welding are all reported as usable, with argon plus 2 to 3 percent hydrogen as the shielding gas base for penetration. Welds in high temperature construction should be full penetration, free of notches and placed in low stress areas, since thermal fatigue rather than static load usually governs.

Standards, testing and certification

One point worth checking on older drawings. EN 10228 part 3 covers ferritic and martensitic forgings, and BS EN 10228-3:2016 refers austenitic and austenitic ferritic stainless forgings to part 4. Since 153 MA is austenitic, EN 10228-4 is the correct ultrasonic acceptance standard, and enquiries that quote 10228-3 for this grade are usually carrying it over from a carbon or alloy steel drawing.

References

Outokumpu, Stainless steels for high service temperatures, Therma range brochure, for grade positioning, EN 10095 maximum service temperature, creep rupture and structural stability ranking, applications, welding guidance, the bell furnace case and trademark ownership. Outokumpu, high temperature stainless steel grades, for weldability and sulphur behaviour. Metalcor datasheet 1.4818 Alloy 153 MA, for EN composition limits, room temperature mechanical and physical properties, the scaling limit, the sulphurous gas caution and filler metal. AZoM, Stainless Steel Grade 153 MA UNS S30415, for typical analysis, hot forming and solution annealing temperatures, welding processes and applications. MakeItFrom, UNS S30415 153 MA Stainless Steel, for hardness, elongation and fatigue strength. Scope statements of BS EN 10228-3:2016, BS EN 10228-4:2016, EN 10095 and EN 10250-4. Where published values differ, both are shown above. Contract values are those on the mill certificate.