The influence of carbon addition on carbide characteristics and mechanical properties of CM-681LC superalloy using fine-grain process

Abstract

This study investigates how carbon addition affects the carbide characteristics and mechanical properties of CM-681LC nickel-base superalloy with grain size of 80 mu m prepared using the fine-grain process. Experimental results indicate that carbon addition from 0.11 wt% to 0.15 wt% greatly increases the amount of carbides, but the shape and size of carbides are similar due to the short solidification time of the fine-grain process, which limits the growth of carbides. The increase of carbides by proper carbon addition effectively improves the tensile strength by about 5% and the tensile elongation by over 30% at room and moderate temperatures (21-760 degrees C). The fracture analyses reveal that the carbon addition in fine-grain CM-681LC superalloy can changes the fracture modes from typical intergranular fracture modes to transgranular and intergranular mixed modes. The better carbon content of CM-681LC superalloy applied in the fine-grain process is 0.15 wt%, which has better mechanical properties. (C) 2011 Elsevier B.V. All rights reserved.