Mechanical properties: experimental temperature tensile strength BMPA specified non-proportional elongation stress p02MPa, elongation, δ5%, room temperature, 665, 450, 8
Physical properties: density: about 84 grams of cubic centimeters.
Melting Point: about 1,300 degrees Celsius.
Coefficient of Thermal Expansion: The coefficient of linear thermal expansion is low, which can maintain good dimensional stability at high temperatures.
Hardness: Typically has a high hardness, up to 40-50 HRC (Rockwell hardness).
Corrosion resistance: Stellite 21 alloy exhibits excellent corrosion resistance and is resistant to a wide range of corrosive media, including acids, alkalis, and brine.
Oxidation resistance: At high temperatures, Stellite 21 alloy resists the effects of oxidation and hot corrosion, maintaining its performance and stability.
Magnetic: Stellite 21 alloys are generally non-magnetic and have low permeability.
Sealing is one of the important performance indicators of valves, abrasion and erosion are the main forms of valve sealing surface failure, and drilling-based alloy is one of the commonly used materials for surfacing valve sealing surface. Cobalt-based alloy has good high-temperature performance, excellent thermal strength, corrosion resistance and thermal fatigue resistance, especially at high temperature, it has excellent scratch resistance, and the valve sealing surface with high wear resistance and corrosion resistance is often used for drill-based alloy surfacing sealing surface.
Overlay the sealing surface of the carbon steel valve body with Stellite 21 electrode to avoid metal welding cracks in the overlay layer and control the Fe element content (5%) is the key to the welding process control. The surfacing process is confirmed by the welding process qualification test and used in production practice to ensure the quality of valve products.
1. Analysis of valve body material and surfacing material.
The valve body ASTM A216 WCB is a carbon steel casting, normalized and tempered, and the structure is pearlite P ferrite F, and its chemical composition is shown in Table 1.
ASTM A216 WCB standard": Maximum specified cross-sectional thickness 25 mm, CE 043;: Maximum specified cross-sectional thickness 25 mm, CE 045。Calculate specimen CE(IIW): about 039. There is a certain tendency to harden.