Characteristics of cobalt-based alloy coating on tool steel prepared by powder feeding laser cladding

• Published in: Optics and laser technology 2007-11, Vol.39 (8), p.1544-1550
• Main Authors: Cui, Chengyun, Guo, Zuoxing, Liu, Yuhua, Xie, Qiongqiong, Wang, Zheng, Hu, Jiandong, Yao, Yuan
• Format: Article
• Language: English
• Subjects: Biological and medical applications; Eutectic; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Industrial applications; Optics; Physics; Tool steel; White layer
• ISSN: 0030-3992; 1879-2545
• DOI: 10.1016/j.optlastec.2006.12.005

Co-based alloy coating was deposited on tool steel by powder feeding laser cladding. Sections of such coatings were examined to reveal their microstructures and phases using scanning electron microscope (SEM) and X-ray diffractometer (XRD). The results showed that the prime phase ( γ-Co dendrite) and other phases, including Cr 23C 6, Co 7W 6, and CrNi existed in the coatings. Some different solidification morphologies, such as planar (at the interface), cellular and dendrite formed, varying from the interface to the surface. Fine microstructures of γ-Co dendrite and lamellar eutectic in dendritical regions strengthened the coatings. Besides, the effects of aged treatment on the microstructure and microhardness of the surface coating were studied. Aged treatment led to the precipitations of some carbide particles (Cr 7C 3 and Co 3C) and boride particles (Co 4B) from the cladded coating, causing an increase in microhardness in the laser-cladded coating.