Process Requirements
The wear-resistant elbow is fabricated using a bimetal wear-resistant composite. Its production mainly employs a combination of vacuum absorption casting with a lost foam mold process, supplemented by other specified manufacturing techniques. The wear-resistant layer is made from composite alloy steel, with each elbow featuring an eccentric compound design. To enhance durability, the outer section of the elbow is thickened based on operational conditions to balance the lifespan between the inner and outer surfaces.
To reduce resistance in coal powder transportation, the elbow’s inner surface must be smooth and streamlined, prohibiting the use of “shrimp waist” welding methods. This ensures the inner diameter remains consistent at 510 mm throughout, without any protrusions or platforms.
The wear-resistant lining consists of a high chromium alloy (minimum grade KMTBCr28), offering a service life exceeding two years and annual wear less than 5 mm. The outer lining thickness is 28 mm, and the inner lining thickness is 22 mm, both with hardness above HRC 55. The outer pipe dimensions for the lining section are 558×10 mm, connecting pipe 508×10 mm, and outer ring 558×22 mm, made from 10 steel. Seamless or welded pipes may be used, complying with standards GB2087 and GB8163.
The bimetal wear-resistant tube’s inner wall made of KMTBCr28 alloy has stable quality and excellent comprehensive performance. Addition of rare earth elements improves alloy quality by refining grain structure and forming a protective surface film. Molybdenum is added to provide antioxidation properties and enhance high-temperature service life. Boron carbide can also be incorporated to control hardness between HRC 45 and 65, resolving the typical hardness versus weldability tradeoff in wear-resistant steel.
