Cobalt Chrome Alloy superalloy is not firmly bonded wit […]
Cobalt Chrome Alloy superalloy is not firmly bonded with the substrate by the orderly precipitation phase to strengthen, but by the solution has been strengthened by the austenite fcc matrix and a small amount of carbide distribution in the matrix. Casting Division Stanley superalloy is to a large extent rely on carbide strengthening. Cobalt-Chromium Alloy will appear in the topological phase with phase such as Sigma phase and Laves is harmful, will make the alloy brittle. Cobalt-Chromium Alloywith less intermetallic compounds for strengthening, because Co3 (Ti, Al) ﹑ Co3Ta and other high temperature is not stable enough, but in recent years the use of intermetallic compounds to strengthen Cobalt-Chromium Alloy has also been developed. Pure cobalt crystals at 417 ° C are densely packed hexagonal (hcp) crystalline structures that are converted to fcc at higher temperatures. In order to avoid this conversion of cobalt chromium alloy superalloy in use, virtually all Cobalt-Chromium Alloy are nickel alloyed to stabilize the tissue from room temperature to the melting temperature.
The general cobalt-base superalloy lacks a coherent reinforcing phase. Although the mid-temperature strength is low (only 50-75% of the nickel-based alloy), it has higher strength at temperatures above 980 ° C, good thermal fatigue resistance, And abrasion resistance, and has good weldability. Suitable for making aviation jet engines, industrial gas turbines, guide vanes and nozzle guide vanes for marine gas turbines, and diesel engine nozzles.
Co-based alloy surfacing technical difficulties are prone to welding defects after welding micro-cracks, cold cracks, surfacing layer off, resulting in product repair or scrap after welding. In the actual production process, as long as the reasonable choice of surfacing process, surfacing layer weld metal to avoid chemical loss and impurities infiltration, dilution rate control under the premise of the quality and performance of the deposited can be guaranteed.