An Introduction to 6% Molybdenum Stainless Sthttps://www.6moly.com/content/materials/6moly/
Brought to you by Ocean International Suppliers, Inc. For information about Ocean's products in 6% Molybdenum, Duplex, Super Duplex, and Titanium.
An Introduction to 6% Molybdenum Stainless Steels
6% Molybdenum Austenitic Alloys and their characteristics
Stainless steels are essentially iron-chromium alloys with sufficient chromium to develop a protective film. While austenitic stainless steels have many desirable properties, including strength, high modules of elasticity, good resistance to corrosion and ease of cleaning, a major drawback is its susceptibility to chloride-induced corrosion; a breakdown of the protective film when exposed to saline water, seawater or brackish water.
To offer maximum resistance to pitting, crevice corrosion and stress corrosion cracking, a number of alloyed steels were developed in the eighties when it was discovered that by increasing the molybdenum content in the stainless steel alloy, the protective film was highly strengthened. To maintain the austenitic structure, nickel is added.
The various Alloys
6Mo Grades:
B25 and B26 developed by Creusot Loire
1925hMo developed by Krupp-VDM
6X and 6XN developed by Allegheny Ludlum
25-6Mo developed by Special Metals (INCO)
254SMO developed by Avesta Sheffield
With its high levels of chromium, molybdenum, and nitrogen, 6Mo alloys have excellent resistance to a wide range of chemicals and are especially suited for high chloride environments such as brackish water, seawater, pulp mill bleach plants and other high chloride process streams.
6Moly alloys provide a chloride resistance superior to that of Alloy 904L, Alloy 20, Alloy 825 and Alloy G. 6Moly is compatible with the common austenitic stainless steels and is often used as a replacement in critical components of larger constructions where Type 316L or 317L has failed. 6Moly alloys have been found in many cases to be technically adequate and a much less costly substitute for nickel-based alloys and titanium.
6Moly alloys are substantially stronger than the common austenitic grades, but are also characterized by high ductility and impact strength. They are readily fabricated and welded.
BENEFITS
High resistance to pitting, crevice and general corrosion.
Very high resistance to chloride stress corrosion cracking.
50% stronger than 300-series austenitic stainless steels.
Excellent impact toughness.
Excellent workability and weldability.
APPLICATIONS
Seawater handling equipment; heat exchanger, cooling water pipes
Pulp mill bleach systems; drums, vats and press rolls.
Tall oil distillation columns and equipment
Chemical processing equipment
Food processing equipment
Desalination equipment
Flue gas desulphurization scrubbers
Oil and gas production equipment
Tanks and pipelines for various chemicals with high halide levels
OTHER CHARACTERISTICS
An extremely high work hardening rate combined with a total lack of sulfur make 6Moly stainless steel very tough to machine. Sharp tools, positive feeds, overpowered machine tools, ample lubrication and slow speeds generally offer the best results. Most common cold work methods will work with these alloys. While it is more difficult to work than other austenitic steels, the hardening will produce increased strength and toughness. The alloys do not respond to heat treatment. Hardening can only be achieved through cold reduction.
Brought to you by Ocean International Suppliers, Inc. For information about Ocean's products in 6% Molybdenum, Duplex, Super Duplex, and Titanium.