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253 MA®

(English) 253 MA® was developed over 30 years ago when the need for a heat resistant stainless steel with high strength, while maintaining good oxidation resistance was present in the industry. 253 MA ®offers outstanding strength and unrivalled heat resistance.

Chemistry

(English)

CrNiSiCMnPSNCeFe
MIN20.0010.001.400.050.140.03Balance
MAX22.0012.002.000.100.800.040.030.200.08

Applications

(English)

  • Boiler Nozzles
  • Corrugated Boxes
  • Cyclones
  • Bar Baskets
  • Radiant Tubes

Fabrication

(English) RA®330 is readily welded using 253 MA® weld fillers of matching composition. 253 MA® AC/DC lime type electrodes are available from stock in popular sizes. 253 MA® bare welding wire is available as straight lengths for GTA welding or spooled for GMA welding.

For best results do not preheat, keep interpass temperature low and use reinforced bead contours.

253 MA® is formed in the same manner as the conventional austenitic stainless steels.

253 MA® and other austenitic grades are quite ductile in the annealed condition. However, when machining, these chromium-nickel alloys work harden more rapidly and require more power to cut than plain carbon steels. Chips tend to be stringy, cold worked material of relatively high ductility.

Oxidation

(English) 253 MA has exceptional oxidation resistance up to about 2000°F (1093°C). Above this temperature, its oxidation resistance drops off. A combination of rare earths and silicon is responsible for the excellent oxidation resistance of this 21% Cr alloy. The rare earths increase diffusion rate of the silicon to the scale-metal interface. This promotes the development of a continuous SiO2 subscale, which in turn slows further oxide growth. Rare earth metals also improve adhesion and elasticity of the oxide scale, even under cyclic conditions. These rare earths, primarily cerium, increase the number of nucleation sites for the oxide. This results in a fine grained chromia and silica scale.

Omlouváme se, tento je k dispozici pouze v Angličtina (Usa), Francouzština, Španělština (Evropa), Italština, Polština, Nizozemština and Němčina.) Angličtina (Usa), Francouzština, Španělština (Evropa), Italština, Polština, Nizozemština and Němčina

Technické zdroje