Alloy steel pipes are tubes made from carbon steel or alloy structural steel with added alloying elements such as chromium (Cr), molybdenum (Mo), vanadium (V), and nickel (Ni). They possess excellent mechanical properties and environmental adaptability.
I. Main Characteristics of Alloy Steel Pipes
– High Strength and High Toughness: Through alloying element strengthening, the tensile strength and yield strength at room temperature and high temperatures are significantly superior to ordinary carbon steel pipes. For example, the room temperature tensile strength of 15CrMo alloy pipe reaches 440–640 MPa, and the yield strength is ≥295 MPa.
– Outstanding High Temperature Resistance: They can operate continuously at 500–650℃. For example, 12Cr1MoVG can operate at temperatures up to 550℃ when used in boiler superheaters; GH90 nickel-based high-temperature alloys are even suitable for extreme environments above 600℃.
– Good Corrosion Resistance and Oxidation Resistance: Chromium forms a dense oxide film, improving resistance to atmospheric, steam, and some acid and alkali corrosion; molybdenum and vanadium enhance resistance to sulfides and hydrogen corrosion.
– Strong creep resistance: Deforms slowly under high-temperature stress, suitable for pressure vessels, steam pipelines, and other long-term pressure-bearing components.
– Recyclable: 100% recyclable, in line with national energy conservation and environmental protection policies.
– Flexible processing: Can be manufactured into different specifications and shapes (round tubes, shaped tubes, etc.) through hot rolling, cold drawing, welding, etc.
>Note: Some high-alloy steel pipes (such as 15CrMo, 12Cr1MoV) have poor weldability and require preheating (200–300℃) and post-weld heat treatment to avoid cracking.
II. Main Application Areas and Typical Uses of Alloy Steel Tubes
Alloy steel pipes are widely used in industrial fields with high requirements for safety and reliability, specifically including:
– Power industry
– Main steam pipelines, superheaters, and headers of supercritical/ultra-supercritical power plant boilers, commonly using materials such as 12Cr1MoVG, 15Cr1MoVG, and T91/P91.
– High-temperature components such as high-pressure cylinders and reheaters in steam turbines. – Petrochemical Industry
– High-temperature and high-pressure reactors, heat exchangers, cracking furnace tubes, and hydrogenation units commonly use 1Cr5Mo, 12Cr2Mo, and 15CrMo.
– Seamless steel pipes for petroleum cracking (GB9948 standard).
– Machinery Manufacturing
– Hydraulic cylinders, shafts, gears, bearing sleeves, and other structural components commonly use 42CrMo, 40Cr, and GCr15.
– Aerospace and Energy
– Aircraft engine combustion chambers and fuel lines (e.g., GH90 nickel-based alloy pipes).
– Titanium alloy steel pipes are used in engine compressors, missile casings, etc.
– Other Fields
– Shipbuilding: Pressure-resistant pipes for boilers and superheaters (GB5312).
– Automotive: Axle sleeves and drive axle tubes (YB/T5035).
– Military Industry: Gun barrels, cannon barrels, etc.
