Laser processing of high chromium white iron

Mechanical properties, such as wear-resistance and hardness, of laser welded and cladded high chromium white iron were investigated. The study involves the laser welding, cladding, and laser surface melt treatment by 3-kW Nd:YAG continuous wave high power laser. The laser welding of 2-mm thick high chromium white iron samples was laser welded in two combinations: iron-to-iron and iron-to-steel. Strong metallurgical bonding was witnessed between not only the iron samples but also iron and steel samples by laser welding. Three types of powder materials were used to laser clad the samples: metal-ceramic (compositionally close to INCO-702), stellite-21, and stellite-1 in order to estimate mechanical property changes and process ability of high chromium white iron. Even though the microstructure of metal-ceramic coating shows worse than stellite powder coatings it has more hardness and wear resistant property which were comparable to base iron. Hardness of metal-ceramic coating was slightly lower than base iron, yet the wear resistance was increased twofold.

DELORO STELLITE 21

Deloro Stellite 21 (UNS R30021), previously known as Stellite 8, is similar to the medical implant alloy ASTM F75. It is a Co-Cr- Mo-Ni alloy that was developed in the mid-1930s as a corrosion resistant alloy, and rapidly found application as a biocompatible hip implant and denture alloy. This alloy consists of a CoCrMo alloy matrix containing dispersed hard carbides that strengthen the alloy and increase its hardness, but that also decrease its ductility. The type, shape, size, and distribution of the carbides are strongly influenced by the processing history of the alloy, and for this reason, the mechanical properties of Deloro Stellite 21 depend greatly on the manufacturing route and any subsequent heat treatments. This datasheet provides information on composition, physical properties, microstructure, hardness, and tensile properties. It also includes information on corrosion resistance as well as machining. Filing Code: Co-139. Producer or source: Deloro Wear Solutions GmbH.

The Effect of Heat Treatment on the Oxidation Resistance of Cobalt-Based Superalloys

Degradation of the mechanical integrity of cobalt-based superalloys can occur as the carbide network is progressively oxidised during high temperature service. In this study, a heat-treatment aimed at redistributing the carbides was tested on two similar commercial Co-based superalloys, one with high C content (Co-101) and one with low C content (Stellite-21), to determine its influence on oxidation resistance. It was found that the carbide phases in the lower C-containing alloy could be solutioned more readily than the higher C-containing alloy, enabling the continuity of the carbide network to be reduced. This resulted in a reduced attack of the carbides down the interdendritic channels during oxidation testing, but increased thickness of the oxide overscale.