Purification and melting method of nickel-based directional solidification columnar and single crystal superalloy master alloys

Abstract

The invention belongs to the technical field of high temperature alloy preparation and particularly relates to a purification smelting method for nickel-based directional solidification column crystaland single crystal high temperature alloy mother alloy. According to the purification smelting method, comprehensive control is conducted from three aspects, namely raw materials, the crucible material and purification smelting process control; the alloy refining temperature in the smelting process is lowered, furthermore, element losses are reduced, and crucible reactions are alleviated; and alloy ingredients can be controlled more precisely, and the contents of impurity elements can be lowered. Meanwhile, after an alloying period is ended, a deoxidation and desulfurizing agent is added, andthe impurity elements such as O and S in the alloy are further reduced. By means of the method, the total quantity of the impurity elements such as O, N and S in the nickel-based directional solidification column crystal and single crystal high temperature alloy mother alloy can be controlled within 5 ppm; meanwhile, the total quantity of the trace impurity elements such as As, Bi, Pb, Sn and Sbis controlled within 5 ppm; and the purity degree of the nickel-based directional solidification column crystal and single crystal high temperature alloy mother alloy is greatly raised.

Description

technical field [0001] The invention belongs to the technical field of superalloy preparation, and in particular relates to a method for purifying and smelting nickel-based directionally solidified columnar crystals and single crystal superalloy master alloys. Background technique [0002] With the continuous development of the aero-engine and gas turbine industry, more and more superalloys are used, and it is required to continuously increase the intake air temperature in front of the turbine to increase thrust, improve efficiency, and reduce fuel consumption. put forward higher requirements. Compared with ordinary equiaxed superalloys, directionally solidified columnar and single crystal superalloys have greatly improved their service temperature, service life, structural stability and comprehensive mechanical properties due to their unique chemical composition and structural properties. . Directional solidification columnar crystals and single crystal superalloys have a...

AI Technical Summary

Problems solved by technology

Most of the published patents on superalloy purification and smelting process adopt high-temperature refining at 1600°C and above. For example, the patent publication number CN106319255A adopts ultra-high temperature refining at 1614°C~1624°C, and the patent publication number is CN1360071A patent medium-high temperature refining The temperature is 1650°C, and the publication number is CN1552928A patent. The high-temperature refining temperature is 1600°C~1650°C. High-temperature refining has certain effects on deoxidation, denitrification and other low-melting point volatile impurity elements. However, high-temperature refining also has the following disadvantages: (1) Accelerate the reaction of the crucible: the alloy liquid reacts violently with the refractory material on the inner surface of the crucible at a higher temperature, and the common crucible contains MgO, Al 2 o 3 , SiO 2 , ZrO, Fe 2 o 3 Such compounds, under high temperature and high vacuum conditions, aggravate the reaction between the above materials and [C] in the alloy liquid, causing pollution of the crucible material to the alloy liquid; at the same time, the crucible material is more eroded, reducing the service life of the crucible

(2) Under high temperature and high vacuum conditions, alloy elements with high saturated vapor pressure such as Cr and Al volatilize more seriously, resulting in a large loss of such alloy elements

Although crucibles made of these materials can remove O and S to a certain extent, it is difficult to realize industrialization because of problems such as high cost and difficult storage.