A method for controlling the grain size of equiaxed superalloy turbine blades

Abstract

The invention is a method for controlling the grain size of an equiaxed crystal superalloy turbine blade. The invention aims at the slender and large-sized thin-walled turbine blade. By controlling the temperature field of the turbine blade during solidification, the parts of the turbine blade with different thicknesses The formation of uniform equiaxed crystals solves the problem of columnar crystals and chilled crystals in the thin-walled area of ​​the exhaust side of this type of casting; at the same time, the looseness of the blade body is significantly improved through the sequential solidification of the turbine blades, and the qualified rate of the turbine blades is improved. Reduce the cost of blade development.

Description

technical field [0001] The invention relates to a method for controlling the grain size of an equiaxed superalloy turbine blade, belonging to the technical field of precision casting. Background technique [0002] In modern advanced aero-engines, the amount of high-temperature alloy materials accounts for 40% to 60% of the total amount of the engine. Every increase in engine thrust-to-weight ratio is strongly dependent on the progress of superalloys. As the thrust-to-weight ratio of the engine continues to increase, the turbine inlet temperature increases significantly, and the turbine blade material gradually develops from equiaxed crystal alloys to directional, single crystal alloys, and its temperature bearing capacity continues to increase. At present, directional and single-crystal alloys have become the dominant materials for aeroengine turbine blades, but equiaxed superalloys are still widely used in turbine blades with lower temperature bearings, integral blisks, la...

AI Technical Summary

Problems solved by technology

In order to obtain finer grains, this method requires a lower pouring temperature. Too low temperature will bring serious loose defects and cannot completely solve the problem of columnar grains at the exhaust side, resulting in extremely low casting pass rate and high cost

In addition, by adding process ribs or implanting insulation materials inside the shell, changing the local temperature field when the blade is solidified, to solve the problem of controlling the columnar crystals and chilled crystals at the exhaust side of the casting, but this method can only be used in a certain range. To a certain extent, the problem of columnar crystals and chilled crystals on the exhaust side can be alleviated, but it cannot be completely solved

[0004] When the ordinary precision casting method is used for the production of slender and large-sized turbine blades, columnar crystals and chilled crystals are easily formed in the thin-walled areas such as the blade exhaust edge, and the alloy solution solidifies in an instant, making it difficult to feed and easily produce porosity and pores. At the same time, non-metallic oxide inclusions cannot be removed by floating, and metallurgical defects such as inclusions are easy to form inside the blade body, which is difficult to meet the metallurgical quality requirements of castings

Therefore, for slender and large-sized thin-walled turbine blades, it is a great challenge to the casting process to ensure the metallurgical quality of the blade while controlling the grain size.

Images