Stellite 12 is a cobalt-based alloy known for its remarkable resistance to wear, corrosion, and even high-temperature oxidation. The alloy is utilized in various critical applications that demand high performance and durability, such as cutting tools, saw blades, hot shears, pumps and valves, and more. This blog will provide a comprehensive guide on Stellite 12, covering its composition, physical and mechanical properties, hardness, heat treatment, welding, and corrosion resistance. So, let’s dive into the world of Stellite 12 and explore its amazing properties.
Stellite 12 Composition
Stellite 12 is a cobalt-chromium-tungsten-carbon alloy with a small content of silicon and molybdenum. The alloy’s cobalt content ranges from 67% to 73%, while the main component of its matrix is chromium carbide. The tungsten content ranges from 8% to 10%, and it plays a crucial role in enhancing the alloy’s hardness, strength, and wear resistance. The high carbon content (up to 3.5%) adds to the alloy’s hardness and wear resistance, while small amounts of silicon and molybdenum improve its high-temperature properties.
| Element | Amount |
|---|---|
| Cobalt (Co) | 59% |
| Chromium (Cr) | 29% |
| Tungsten (W) | 9% |
| Nickel (Ni) | 3% |
| Iron (Fe) | 2% |
| Carbon (C) | 1.8% |
Stellite 12 Physical Properties
Stellite 12’s remarkable physical properties make it an attractive choice for wear-resistant applications. It has a density of about 8.4 g/cm3, which is relatively high for an alloy. The melting point of Stellite 12 is around 1305°C, making it capable of withstanding high-temperature environments. The alloy’s thermal conductivity is about 23 W/mK, which is lower than copper but higher than many other alloys. This property suggests that the alloy can handle moderate heat dissipation effectively.
Stellite 12 Mechanical Properties
The mechanical properties of Stellite 12 include its tensile strength, yield strength, elongation, and hardness. Its tensile strength ranges from 1000 to 1200 MPa, while its yield strength is around 800 MPa. The elongation of Stellite 12 ranges from 1% to 15%, depending on the heat treatment process. The alloy’s hardness ranges from 45 HRC to 55 HRC, making it one of the hardest cobalt-based alloys available.
Stellite 12 Hardness
Stellite 12 is known for its remarkable hardness and wear resistance due to its unique composition. It can withstand extreme abrasion and erosion, making it ideal for cutting, grinding, drilling, or sawing applications. The hardness of Stellite 12 is mainly dependent on its tungsten carbide content, which ranges from 8% to 10%. The higher the tungsten content, the higher the alloy’s hardness.
Stellite 12 Heat Treatment
Stellite 12 can be heat-treated to improve its mechanical and physical properties, especially its hardness, strength, and toughness. The most common heat treatment process for Stellite 12 is solution treatment followed by age hardening. Solution treatment involves heating the alloy to 1150°C to 1200°C for about 1 to 2 hours and then quenching it in water. The age-hardening process involves heating the alloy between 650°C to 750°C for several hours. The heat treatment process enhances the alloy’s microstructure and improves its properties.
Stellite 12 Welding
Stellite 12 is weldable using various welding techniques, such as manual metal arc welding, gas tungsten arc welding, and plasma arc welding. However, due to its significant tungsten content, welding can pose challenges, such as cracking and porosity. Therefore, it is crucial to use appropriate welding procedures, filler metals, and preheating techniques to minimize these challenges.
Stellite 12 Corrosion Resistance
Stellite 12 is highly corrosion-resistant in harsh environments, such as acids, alkalis, saltwater, and even high-temperature oxidizing atmospheres. The alloy’s corrosion resistance is mainly due to its high chromium content, which forms a passive film that protects the underlying matrix from corrosion. This property makes Stellite 12 ideal for applications requiring excellent wear and corrosion resistance.
Conclusion
Stellite 12 is a unique cobalt-based alloy with remarkable wear resistance, hardness, strength, and corrosion resistance properties. Its unique composition and microstructure make it an attractive choice for various demanding applications, such as cutting tools, saw blades, hot shears, and pumps and valves. In this blog post, we covered the essential aspects of Stellite 12, including its composition, physical and mechanical properties, hardness, heat treatment, welding, and corrosion resistance. We hope this guide has provided valuable insights into Stellite 12 and its unique properties.
