Cobalt-chromium Alloy is a kind of ability to withstand […]
Cobalt-chromium Alloy is a kind of ability to withstand various types of wear and corrosion and high temperature oxidation of cemented carbide. Which is commonly referred to as the cobalt-based alloy, the Cobalt-chromium Alloy alloy by the American Elwood Hayness in 1907 invention. Cobalt-chromium Alloy alloy is cobalt as a main component, containing a considerable amount of nickel, chromium, tungsten and a small amount of molybdenum, niobium, tantalum, titanium, lanthanum and other alloying elements, and occasionally also contains a class of iron alloy. According to the different composition of the alloy, they can be made of wire, powder for hard surfacing, thermal spraying, spray welding and other processes, can also be made of castings and powder metallurgy pieces.
Unlike other superalloys, the Cobalt-chromium Alloy superalloy is not reinforced by an ordered precipitated phase that is firmly bonded to the substrate, but consists of austenite fcc matrix that has been solidified and has a small amount of carbide present in the matrix. Casting Division is too high-temperature alloy is to a large extent rely on carbide strengthening. Pure cobalt crystals below 417 ° C are closely packed hexagonal (hcp) crystal structures and are converted to fcc at higher temperatures. In order to avoid such a change in the use of superstructures, it is practically all alloyed by nickel to stabilize the structure at room temperature to the melting point. Cobalt-chromium Alloy alloy has a flat fracture stress-temperature relationship, but at 1000 ℃ above but show higher than other high temperature has excellent thermal corrosion resistance, which may be because the alloy contains a higher chromium content.
The early Cobalt-chromium Alloy of the legislation with non-vacuum smelting and casting process to produce. Later developed into alloys, such as Mar-M509 alloy, containing more active elements such as zirconium, boron, etc., with vacuum smelting and vacuum casting production. The size and distribution of carbide particles in the Cobalt-chromium Alloy alloy and the grain size are very sensitive to the casting process. The casting process parameters must be controlled in order to achieve the desired lasting strength and thermal fatigue properties of the casting division.
Cobalt-chromium Alloy alloy need heat treatment, mainly to control the precipitation of carbides. For the Casting Division Tai Li alloy, the first high-temperature solution treatment, the temperature is usually about 1150 ℃, so that all the primary carbide, including some MC-type carbide dissolved in solid solution and then at 870-980 ℃ aging treatment, so that the carbide (the most common for the M23C6) re-precipitation.