Patent Application
20140090753
This disclosure relates to alloy components that are solution heat treated and, more particularly, relates to selecting a solution heat treatment temperature for the components.
Alloy components may be solution heat treated at a pre-selected temperature. The heat treatment is used to control the microstructure of the alloy and obtain desired mechanical properties within the components.
A method for adjusting properties of components made of an alloy according to an exemplary aspect of the present disclosure includes providing historical data for one or more properties of a plurality of components made of an alloy and that are produced at different times over a time period, wherein the plurality of components are solution heat treated at a pre-established solution heat treatment condition. A trending change in the one or more properties over the time period is then identified and test specimens made of the alloy and that differ in shape from the plurality of components are provided. The test specimens are divided into a plurality of groups and each of the plurality of groups is solution heat treated and precipitation heat treated at a different one of a plurality of heat treatment conditions. Each of the plurality of heat treatment conditions includes a set of at least a solution heat treatment temperature, a heating rate and a cooling rate. The test specimens are mechanically tested after the solution heat treating and precipitation heat treating to provide empirical data. The empirical data is compared to predetermined performance criteria. A solution heat treatment condition is identified from the plurality of heat treatment conditions over which the empirical data meets the predetermined performance criteria. A pre-established solution heat treatment condition is adjusted for future ones of the plurality of components according to the identified solution heat treatment condition.
In a further non-limiting embodiment, the alloy is a nickel-based alloy.
In a further non-limiting embodiment of any of the foregoing examples, the alloy is a nickel-based alloy that has gamma double prime phase, gamma prime phase and a delta phase present after the solution heat treating and precipitation heat treatment.
In a further non-limiting embodiment of any of the foregoing examples, the alloy is a nickel-based alloy that has a gamma prime phase and a delta phase present after the solution heat treating and precipitation heat treatment.
In a further non-limiting embodiment of any of the foregoing examples, the alloy is a nickel-based alloy that has gamma prime phase present after the solution heat treating and precipitation heat treatment.
In a further non-limiting embodiment of any of the foregoing examples, the empirical data and performance criteria include ultimate tensile strength, 0.2% yield strength, tensile percent elongation and tensile reduction in area.
In a further non-limiting embodiment of any of the foregoing examples, the empirical data and performance criteria include tensile stress rupture life, tensile percent elongation and tensile reduction in area.
A further non-limiting embodiment of any of the foregoing examples includes solution heat treating the future ones of the plurality of components at the identified heat treatment condition to non-destructively qualify that the future ones of the plurality of components meet the predetermined performance criteria.
A further non-limiting embodiment of any of the foregoing examples includes adjusting the pre-established solution heat treatment condition for each of a plurality of batches of the alloy, the plurality of batches of the alloy varying from each other in chemical composition.
A method of estimating an unknown solvus for a phase of a given alloy according to an exemplary aspect of the present disclosure includes providing empirical data of a plurality of alloys from an alloy class, where the empirical data at least includes chemical compositions, heating rates, cooling rates and alloy solvus temperatures of the plurality of alloys. An alloy chemical composition, a selected heating rate and a selected cooling rate of another alloy from the alloy class that has an unknown solvus temperature is provided. The unknown solvus temperature is estimated based upon the empirical data to provide an estimated solvus temperature of the alloy. A solution heat treatment temperature is established corresponding to the estimated solvus temperature at which to treat a component that includes the alloy.
In a further non-limiting embodiment of any of the foregoing examples, the estimating of the unknown solvus temperature includes determining an influence of the chemical compositions on the solvus temperatures of the plurality of alloys.
In a further non-limiting embodiment of any of the foregoing examples, the estimating of the unknown solvus temperature includes determining an influence of the heating rates on the solvus temperatures of the plurality of alloys.
In a further non-limiting embodiment of any of the foregoing examples, the estimating of the unknown solvus temperature includes determining an influence of the cooling rates on the solvus temperatures of the plurality of alloys.
In a further non-limiting embodiment of any of the foregoing examples, the estimating of the unknown solvus temperature includes determining an influence of each of the chemical compositions, the heating rates and the cooling rates on the solvus temperatures of the plurality of alloys.
In a further non-limiting embodiment of any of the foregoing examples, the estimating of the unknown solvus temperature includes determining an influence of the chemical compositions, heating rates and cooling rates on the solvus temperatures of the plurality of alloys and the estimating of the unknown solvus temperature includes comparing the alloy chemical composition, the selected heating rate and the selected cooling rate of the alloy that has the unknown solvus temperature to the chemical compositions, the heating rates and the cooling rates of the plurality of alloys to provide the estimated solvus temperature of the alloy.
In a further non-limiting embodiment of any of the foregoing examples, the alloy class is a nickel-based alloy.
In a further non-limiting embodiment of any of the foregoing examples, the nickel-based alloy has gamma double prime phase, gamma prime phase and a delta phase present after a solution heat treatment and a precipitation heat treatment.
In a further non-limiting embodiment of any of the foregoing examples, the nickel-based alloy has a gamma prime phase and a delta phase present after a solution heat treatment and a precipitation heat treatment.
In a further non-limiting embodiment of any of the foregoing examples, the nickel-based alloy has gamma prime phase present after a solution heat treatment and a precipitation heat treatment.
A method for selecting a solution heat treatment condition of an alloy on a per-batch basis according to an exemplary aspect of the present disclosure includes, for each batch of an alloy, providing test specimens made of the alloy and that differ in shape from the plurality of components. The test specimens are divided into a plurality of groups and each of the plurality of groups is solution heat treated at a different one of a plurality of heat treatment conditions and precipitation heat treated. Each of the plurality of heat treatment conditions includes a set of at least a solution heat treatment temperature, a heating rate and a cooling rate. The test specimens are mechanically tested after the solution heat treating and precipitation heat treating to provide empirical data. The empirical data is compared to predetermined performance criteria to identify a solution heat treatment condition from the plurality of heat treatment conditions over which the empirical data meets the predetermined performance criteria. A pre-established solution heat treatment condition is established to treat a plurality of components according to the identified heat treatment condition.
The various features and advantages of the present disclosure will become apparent to those skilled in the art from the following detailed description. The drawings that accompany the detailed description can be briefly described as follows.
As shown in
Once the trending change in one or more of the properties is identified, a series of steps as follows can be used to adjust the pre-established solution heat treatment condition and thereby improve the one or more properties that have trended in an undesired direction over the time period. Step 26 includes providing test specimens made of the alloy and that differ in shape from the plurality of locations and components. That is, the components have a shape that is designed for the intended end use, while the test specimens have a standardized shape that is appropriate for mechanical testing, such as a “dog-bone” or “dumb-bell” shape. The test specimens are untreated, at least with regard to the solution heat treatment.
The test specimens are then divided at step 28 into a plurality of groups. The groups are solution heat treated and precipitation heat treated at a different one of a plurality of heat treatment conditions. Each of the plurality of heat treatment conditions includes a set of at least a solution heat treatment temperature, a heating rate and a cooling rate. After the solution heat treatment and precipitation heat treatment, the test specimens are mechanically tested at step 30 to provide empirical data. As discussed above, the one or more properties can include certain mechanical properties of the plurality of components. In this regard, the empirical data that is collected in step 30 by mechanically testing the test specimens and the performance criteria include the same properties. The empirical data is then compared at step 32 to pre-determined performance criteria. For example, the pre-determined performance criteria can correspond to minimum or desired mechanical properties of the components for proper operation of the components in the intended end use.
Step 34 then includes identifying a solution heat treatment condition from the plurality of heat treatment conditions over which the empirical data meets the predetermined performance criteria. Once the solution heat treatment condition is identified, step 36 then includes adjusting the pre-established solution heat treatment condition for future ones of the plurality of components according to the identified solution heat treatment condition. The adjustment to the pre-established solution heat treatment condition can include changing the solution heat treatment temperature, the heating rate, the cooling rate or any combination thereof. The testing and verification of the properties of the test specimens and then adjusting the pre-established solution heat treatment condition ensures that the one or more properties of the components meet the pre-determined performance criteria.
Although the method 20 can be applied to many different types or classes of alloys, an alloy of interest for diffuser cases and other gas turbine engine components is nickel-based alloy, one example of which can be found in U.S. Pat. No. 4,888,253, incorporated herein by reference, which has gamma double prime phase, gamma prime phase and delta phase. In another example, the alloy is a nickel-based alloy that has gamma prime phase and delta phase, examples of which can include alloys found in U.S. Pat. No. 6,730,264, incorporated herein by reference, and Alloy 718Plus). In another example, the alloy is a nickel-based alloy that has gamma prime phase, one example of which includes Waspaloy.
Additionally, the method 20 can be used to non-destructively qualify that the components meet the pre-determined performance criteria. For example, by mechanically testing the test specimens and comparing the empirical data to the pre-determined performance criteria, a user can conclude that the plurality of components that are solution heat treated at the adjusted pre-established solution heat treatment condition also meet the pre-determined performance criteria.
The following example is based upon a nickel-based alloy that has a gamma double prime phase, a gamma prime phase and a delta phase after solution heat treating and precipitation heat treatment. Historical data were collected for one or more properties of components made of the alloy over a period of years. A trending change in one or more of the properties was identified over the time period and it was determined, as represented in
As shown in
As shown in
Similarly, the heating rate and/or the cooling rate (or ranges thereof) can be identified. Once the condition was identified, components that were made of the same alloy as the test specimens that were used to identify the condition range, were solution heat treated at the identified condition to ensure that the components met the property requirements or performance criteria.
As another example, a variation of the method 20, optionally without steps 22 and 24, can be used to adjust the pre-established solution heat treatment condition on a per-batch basis of the alloy. As used herein, a “batch” differentiates the alloy by time of production of the alloy, but does not necessarily mean that the alloy was produced using batch processing techniques. For example, each batch of the alloy may vary slightly from a nominal chemical composition. Typically, chemical compositions of alloys, such as nickel-based alloys, are defined with regard to specific ranges of each element of the chemical composition. Thus, the actual amount of any given element can vary within the specified range of that element from batch-to-batch of the alloy. These slight differences in chemical compositions between batches can change the response of a batch to a given baseline or pre-established solution heat treatment condition. In this regard, the modified method 20 can be used on each batch to adjust or tailor the pre-established solution heat treatment condition for that particular batch. That is, one batch of the alloy can have a first adjusted pre-established solution heat treatment condition and another, different batch of the alloy can have a different adjusted pre-established solution heat treatment condition that differs in at least one of solution heat treatment temperature, heating rate or cooling rate. This allows the properties of the batch of the alloy, and thus the properties of the components that are to be produced from that batch of the alloy, to be tailored to the particular batch of the alloy.
The method 50 includes, at step 52, providing empirical data of a plurality of alloys from an alloy class. For the purpose of this disclosure, an alloy class is determined according to the base metal (most abundant metal) of the alloy. For example, nickel-based alloys are considered to be an alloy class. Thus, the alloys from which the empirical data is provided all include the same base metal but may differ in the amounts and/or types of other elements. In a further example, the alloys from which the empirical data is provided can have all of the same elements, with multiple elements being present in different amounts in the alloys.
The empirical data at least includes chemical compositions, heating rates, cooling rates and alloy solvus temperatures of the plurality of alloys. At step 54, an alloy chemical composition, a selected heating rate and a selected cooling rate of another alloy from the alloy class that has an unknown solvus temperature are provided. At step 56, the unknown solvus temperature is then estimated based upon the empirical data to provide an estimated solvus temperature of the alloy. A solution heat treatment temperature corresponding to the estimated solvus temperature is then established at which to heat treat a component that includes the alloy.
For example, estimation of the unknown solvus temperature can include determining an influence of one or more of the chemical compositions, the heating rates and the cooling rates on the solvus temperatures of the plurality of the alloys. For example, by comparing the chemical compositions, the influence of chemical composition with regard to one or more of the elements on a baseline solvus temperature can be determined. Similarly, the influence of the heating rates and the cooling rates on a baseline solvus temperature can be determined. By then comparing the chemical composition, the selected heating rate and the selected cooling rate of the alloy of unknown solvus temperature to the empirical data and determined influences, the unknown solvus temperature of the alloy can be estimated. Optionally, the method 50 can further include a verification of the selected solution heat treatment temperature. The verification can include experimental testing of the alloy, components formed of the alloy or a combination thereof. The selected solution heat treatment temperature can then be modified based upon the verification results.
A component that is made of the same alloy as the alloy with the unknown solvus temperature can then be solution heat treated according to the estimated solvus temperature, selected heating rate and selected cooling rate, without actual testing or determination of the unknown solvus temperature. For example, the selected solution heat treating temperature of the alloy can be a pre-determined increment above the estimated solvus temperature.
In another application of the present disclosure, variations in composition from elemental changes, such as niobium content, can be characterized by their effect on the empirical data, which may be reflected in the respective heat treatment temperature capability curve. The empirical property versus temperature may indicate changes in the resultant best-fit curve in
Although a combination of features is shown in the illustrated examples, not all of them need to be combined to realize the benefits of various embodiments of this disclosure. In other words, a system designed according to an embodiment of this disclosure will not necessarily include all of the features shown in any one of the Figures or all of the portions schematically shown in the Figures. Moreover, selected features of one example embodiment may be combined with selected features of other example embodiments.
The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the essence of this disclosure. The scope of legal protection given to this disclosure can only be determined by studying the following claims.
