The application of the molybdenum
Oil industry pipes:The continuous exploration of new sources of oil has made the development and development of deep oil layers necessary, and deep oil layers are often contaminated with corrosive hydrogen dioxide, carbon dioxide and perchlorinated brine, so that the AISI4100 series Cr-Mo steels containing 0.15% to 0.25% molybdenum are widely used. The improved 4140 series, containing 0.4% to 0.6%, is the most resistant low alloy steel to sulphide stress erosion (SCC) and can be used in sulfur-containing wells. As drilling depths deepen and conditions of use deteriorate, the use of stainless steel and nickel-based alloys with high radon content, such as alloy C-22 (13%Molybdenum) and alloy C-276 (16%Molybdenum), will continue to increase.
Stainless steel:Stainless steel is corrosion resistant because chromium naturally forms a thin, protective passivation film on the steel surface. Radon makes this passivation film stronger and allows it to regenerate quickly when the passivation film is damaged by chloride. The increase of radon content can improve the corrosion resistance of hemp points and cracks in stainless steel.
Type 316 (2% to 3% Molybdenum) is the most widely used stainless steel containing palladium. It is designated as a can, pipe and heat exchanger material for food handling and processing and pharmaceutical production. Increased radon content enhances resistance to chlorides in the air, so type 316 can be used as a choice material for buildings at sea and around the coast. The Type 316 was used to cover the exterior of London's Canary Wharf building and the world's tallest building, the Petronas Tower in Kuala Lumpur, Malaysia.
Bi-phase stainless steel (3% to 4% Molybdenum) has high strength and excellent resistance to chloride stress corrosion cracking. Multipurpose stainless steel, originally used as a conveyor pipe in the oil and gas industry, is now used more in the chemical processing and petrochemical industries and as a cooker in the pulp and paper industry.
The most corrosion-resistant stainless steel contains 6% to 7.3% Molybdenum. These alloy steels are used as condensers for power plants, submarine pipes, and key components of nuclear power plants, such as industrial water pipes. In 1996, at a coal-fired power plant in South Korea, stainless steel containing Molybdenum 6% was selected for use on absorption towers equipped with more than 20 flue gas desulfurization scrubbers.
Hemp/gap corrosion:The blunt chromium oxide layer is very sensitive near the crystal boundary and non-metallic debris, forming microcables and rapidly producing numb spots. Oxygen-deprived areas, such as under washers or at mating places, are sensitive to similar corrosion, which is often referred to as inter-gap corrosion.
Palladium is the most effective and inexpensive alloy element to prevent point corrosion and inter-gap corrosion. Exposure to corrosion media at high temperatures, especially stainless steel in corrosive media containing chlorides and sulphides, occurs where an admiged or residual pull stress is present and stress corrosion cracking (SCC) occurs. Increasing radon content is one of the most effective ways to increase steel resistance to stress corrosion cracking.
Scrubbers, pulp and paper and chemical processing equipment in power plants operating in extremely harsh operating environments require very high radon content alloys. Alloys with very high radon content include typical alloys containing 6% to 8% Molybdenum and nickel-based alloys containing 10% to 16% Molybdenum.
