Enhanced Corrosion Resistance of a Transient Liquid Phase Bonded Nickel-Based Superalloy
- PDF / 1,818,847 Bytes
- 8 Pages / 593.972 x 792 pts Page_size
- 54 Downloads / 186 Views
ralloys are essential materials extensively used in the manufacture of gas turbine hot section components for various aerospace and power generation applications.[1] The materials possess excellent mechanical and corrosion properties in harsh and challenging environments, such as nuclear power and chemical processing plants and more recently in the oil and gas industry.[2] Joining is a crucial manufacturing process, as it enables the creation of single large continuous structures that are rather intricate to manufacture via casting or other manufacturing processes, and it is also used in the repair or refurbishment of service-damaged components. Conventional fusion welding is the most common joining process used in manufacturing; however, the application of conventional fusion welding to join superalloys, particularly, nickel-based superalloys that are strengthened by c¢ precipitates is severely limited.[3,4] This is due to the high susceptibility of these materials to weld-cracking during welding and postweld heat treatments.[5–7] Transient liquid phase (TLP) bonding is fast
O.J. ADEBAJO, Graduate Student, and O.A. OJO, Professor, are with the University of Manitoba, Winnipeg, MA R3T 5V6, Canada Contact e-mails: [email protected], olanrewaju.ojo@umanitoba. ca. Manuscript submitted February 18, 2016. Article published online November 2, 2016 26—VOLUME 48A, JANUARY 2017
becoming an attractive joining process for these difficult-to-weld alloys without the associated complication of cracking, and with technological and cost advantages over fusion welding and solid-state diffusion bonding. The joining technique involves the use of a low melting filler alloy (or interlayer material) which contains melting point depressant (MPD) solute(s), and is sandwiched between the base materials (substrate) to be joined. The joint formation occurs via diffusion-controlled isothermal solidification of solute-rich liquid phase that forms temporarily between the substrates on heating to the bonding temperature. The filler alloy used during TLP bonding has varied from simple binary braze alloy to composite powder mixture of superalloy base material (gap-filler alloy) and braze alloy (filler alloy).[8] Corrosion, the deterioration of a material due to chemical interactions with the environment, is a key factor in the selection and use of superalloys for engineering applications. Several studies have been performed on TLP bonding of superalloys, including evaluation of mechanical properties of bonded materials;[9–15] however, very limited work has been reported on the effects of TLP bonding on corrosion resistance of superalloys. Joining creates a microstructure that is although similar to, yet somewhat different from, the substrate material in the joint region and hence the fundamental relationship between the material and its microstructure is altered for the joint,[16] since the characteristics of any material is a function of its microstructure. Therefore, the objective of this study is to analyze the corrosion performance of a TLP-bonded IN 7
Data Loading...
