Alloy 33 (UNS R20033 / W.Nr. 1.4591)

Alloy 33 (UNS R20033, N08033 / W.Nr. 1.4591)

Alloy 33 (UNS R20033, N08033 / W.Nr. 1.4591) is a high-chromium austenitic alloy which combines ease of fabrication with outstanding resistance to highly oxidizing media such as concentrated sulphuric acid. Despite its low molybdenum content, it shows excellent resistance to localized corrosion in halide media. The nitrogen content ensures high mechanical properties with good ductility. Alloy 33 is a material that can be used for many applications in the chemical processing industry.

Equivalent Grades

Trademark	GB	GOST	ASTM	UNS	DIN	W.Nr.	NF	BS	JIS	SS
Nicrofer 3033	NS1405	–	Alloy 33	R20033 N08033	X1NiCrMoCuN 33-32-1	1.4591	–	–	–	–

Chemical Composition, %

Alloy	C	Si	Mn	P	S	Cr	Ni	Mo	Cu	N	Fe
Alloy 33	≤0.015	≤0.50	≤2.00	≤0.020	≤0.010	31.0-35.0	30.0-33.0	0.5-2.0	0.3-1.2	0.35-0.60	Bal

Typical Physical and Mechanical Properties (RT, Annealed)

Density, g/cm3	Melting Point, ℃	Tensile Strength, MPa	Yield Strength, MPa	ELongation, %	Hardness, HBW
7.90	1330-1370	720-920	≥380	≥40	≤240

Available Products and Specifications

Rod, Bar, Wire and Forgings	ASTM B649, ASME SB649
Plate, Sheet and Strip	ASTM B625, ASME SB625
Pipe and Tube	–
Welding Product	–
Others	–

Features

Excellent resistance against pitting corrosion in media containing chloride and against general corrosion in hot mineral acids, mixed acids and alkalis as well as seawater and brackish water
High strength and high ductility even in high temperatures
Good workability and welding characteristics
ASME approval for pressure vessels in the temperature range from -196℃ to 450℃

Applications

Heat recovery and distribution systems in the sulfuric acid production
Pipes and heat exchangers for sulfuric acids contaminated with chlorides
Vessels for storage and transport of nitric acid/hydrofluoric acid mixtures
Seawater conducting pipes, condensers, coolers, etc. with excellent resistance against pitting corrosion
Production and use of NaOH and KOH up to 70 wt.-% and max. 170℃
Urea solutions in the concentration range from 5 to 90 wt.-%
Components for the pulp and paper industry
Vessels and pipes in purified terephthalic acid (PTA) plants