Method for preventing monocrystal blades from having mixed crystal defects

Abstract

The invention relates to the field of directional solidification of alloys, particularly relates to a method for preventing monocrystal blades from having mixed crystal defects. The method is characterized in that in the process of preparing an investment casting mould case for monocrystal blade production, a ceramic fiber insulation block is implanted into the position on a mould case at a blademargin plate at which is easy to have mixed crystal defects, the ceramic fiber insulation block is prefabricated into a U-shaped block according to the shape of the mould case at the blade margin plate, and a U-shaped cavity of the ceramic fiber insulation block contains all mould cases at the blade margin plate. The method disclosed by the invention has the advantages that through using the characteristics that the thermal conductivity of the ceramic fiber insulation block is extremely low, the liquidus temperature TL-isotherm form (see Figure 2) generated when a solidification front reachesthe monocrystal blade margin plate in the process of alloy solidification at the monocrystal blade margin plate is controlled reasonably, so that when the margin plate is close to a directional solidification thermal baffle plate area, the heats are mainly outputted by a monocrystal blade body, and the spontaneous nucleation at the margin plate is avoided, thereby ensuring the smooth growth of monocrystals.

Description

technical field [0001] The invention relates to the field of directional solidification of alloys, in particular to a method for preventing miscellaneous crystal defects in single crystal blades. Background technique [0002] With its unique characteristics of small size, light weight, high power, quick start, and less auxiliary equipment, gas turbines have first been widely used in the field of aero-engines. In order to improve the functions and efficiency of aero-engines, people have successfully used high-temperature alloys to direct The solidification technology makes the turbine blades into a single crystal form, which increases the high-temperature working life of the blades dozens of times. With the continuous advancement of gas turbine technology, gas turbines that were originally only used in the aviation field have been used in electric power, transportation, ships, and tanks. Petroleum, chemical, municipal, textile and many other fields have been widely used. In t...

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Problems solved by technology

[0002] With its unique characteristics of small size, light weight, high power, quick start, and less auxiliary equipment, gas turbines have first been widely used in the field of aero-engines. In order to improve the functions and efficiency of aero-engines, people have successfully used high-temperature alloys to direct The solidification technology makes the turbine blades into a single crystal form, which increases the high-temperature working life of the blades dozens of times. With the continuous advancement of gas turbine technology, gas turbines that were originally only used in the aviation field have been used in electric power, transportation, ships, and tanks. Petroleum, chemical, municipal, textile and many other fields have been widely used. In the past 30 years, the efficiency of industrial gas turbines has been greatly improved by applying the single crystal blade technology of aero-engines to the blade manufacturing of large-scale industrial gas turbines; due to the industrial The size of gas turbine blades is much larger than that of aviation blades, making the production of single crystal castings extremely difficult. Currently, one of the main problems encountered in the production of single crystal turbine blades with complex shapes by directional solidification technology is the formation of miscellaneous crystals. Due to the sudden change in the cross-sectional area of ​​the casting in the direction of vertical heat flow, the blade edge plate is prone to nucleation and growth of new grains

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