HY help you to Learn about the Stellite alloy in one article
（HY industry- Technical Center internal data）
Stellite alloy is a hard alloy that can resist various types of wear and corrosion as well as high temperature oxidation. Commonly known as cobalt-based alloy, Stellite alloy was invented by American Elwood Hayness in 1907.Stellite alloy is mainly composed of cobalt, containing a considerable amount of nickel, chromium, tungsten and a small amount of molybdenum, niobium, tantalum, titanium, lanthanum and occasionally a class of alloys containing iron.Depending on the composition of the alloy, they can be made into wire, powder used for hard surfacing, thermal spraying, spray welding and other processes, as well as cast and forged parts and powder metallurgy parts
Stellite Alloy applications:
Stellite Alloy is mainly composed of cobalt, containing a considerable amount of nickel, chromium, tungsten, a small amount of molybdenum, niobium, tantalum, titanium, lanthanum and occasionally a class of alloys containing iron.Depending on the composition of the alloy, they can be made into wire, powder (used in hardfacing surfacing, thermal spraying, spray welding and other processes), cast or forged parts and powder metallurgy parts.
Typical grades of Stellite alloy are:
Stellite1（UNS R30001），Stellite4，Stellite6（UNS R3006），Stellite12（UNS R30012），Stellite20，Stellite21（UNS R30021），Stellite31，Stellite100 etc.
Stellite Alloy Grade table
Classification by actual use:
Stellite alloy can be divided into Stellite wear-resistant alloy, Stellite high-temperature alloy, Stellite wear-resistant alloy and water-solution corrosion-resistant alloy.Generally, under the operating condition, both wear resistance and high temperature resistance or wear resistance and corrosion resistance can be achieved. Some working conditions may also require high temperature resistance, wear resistance and corrosion resistance at the same time. The more complicated the working condition, the better the advantages of Stellite alloy can be reflected.
Difference with other high temperature alloy material:
Stellite high temperature alloys are not strengthened by ordered precipitates that bind firmly to the matrix, but by a small amount of carbides in the austenite FCC matrix and matrix that have been reinforced by solid solution.Cast astrid superalloy is, however, heavily fortified by carbide.Pure cobalt crystals under 417 ℃ is close the six-party (HCP) crystal structure, into the FCC at higher temperatures.In order to avoid this transition during use, virtually all styrenic alloys are nickel alloyed to stabilize the tissues at room temperature to melting point temperature.Department too stand alloy has a flat fracture stress and temperature relations, but it shows more than any other in above 1000 ℃ high temperature alloy has more excellent thermal corrosion resistance, this may be because the alloy chromium content is higher, this is a feature of this kind of alloy.
Excellent thermal stability：
The thermal stability of carbide in Stellite alloy is good.Temperature rise, carbide agglomeration grow up faster than nickel-based alloy phase grew up in both slower, back in the temperature of the substrate is higher (up to 1100 ℃), therefore, as the temperature rose department too alloy strength drops tend to be slow.
Very strong thermal corrosion resistance
Stellite is generally believed that department too stand alloy is better than that of nickel base alloy, in this respect is cobalt sulfides melting point (such as Co – Co4S3 eutectic, 877 ℃) than nickel sulfide melting point (645 ℃) such as Ni – Ni3S2 eutectic, and sulfur in the diffusion rate of cobalt nickel in the middle and lower than.And since most of the Stellite alloy contains more chromium than nickel base alloy, alkali metal sulfate (such as the Cr2O3 protective layer of Na2SO4) can be formed on the surface of the alloy.However, the antioxidant capacity of Stellite alloy is usually much lower than that of nickel base alloy.