| GH742alloy is a kind of Nickel-based superalloy which is precipitation strengthening by γ’phase. The content of Ti, Al, Nb which are the forming elements of γ’ is higher (The total content of Ti, Al, Nb is7.8%). It belongs to hard-deformation type superalloy. When GH742is under complete heat treatment, the content of its strengthening phase γ’ can reach35%. Moreover, due to the solution strengthening effect of Mo, Co and the grain strengthening effect of micro alloying elements like La、B、Ce, GH742has good high temperature properties. And it is widely applied to manufacture turbine disk, compressor disk, shaft, fasteners and other components.The process flow of this trial-produce of GH742forging piece is as follows: double vacuum melting (VIM+VAR), forging cogging and hot die forging forming. During the development, detailed researches as GH742alloy composition control, double vacuum smelting process, steel ingot uniformity technology, forging cogging process, die forging process and heat treatment were made and all got satisfied results. For the die forging of superalloy which is hard to distort, based on the conception of isothermal forging, we adopted hot die forging process and developed aviation use GH742die forging turbine disk piece for the first time, which fills in a gap of forging piece trituration of this kind of alloy at domestic. The process technology is of lead position in domestic level. The performance of forging piece complys with the requirement of subject standard, and is equivalent to foreign material level. In the process of development, we have carried on beneficial exploration about above mentioned processes.The successful development of superalloy which is hard to distort such as GH742supplies support for the localization of aviation and spaceflight engines as well as gas turbine engine for naval vessel. The technology such as smelting, processing and die forging laid a firm foundation for the development of other superalloy which is hard to distort. |
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