Abstract:
A component and a method of processing a component are disclosed. The method includes providing a base metal having a feature, removing the feature to form a processed region, applying a first layer to the processed region, and applying a second layer to the first layer. The base metal, the first layer, and the second layer each have predetermined thermal expansion coefficients, yield strengths, and elongations. The processed component includes the first layer applied to a processed region of the base metal and a second layer applied to the first layer.

Description:
FIELD OF THE INVENTION 
     The present invention is generally directed to methods of processing gas turbine components and gas turbine components. More specifically, the present invention is directed to methods of processing gas turbine diaphragms and processed gas turbine diaphragms. 
     BACKGROUND OF THE INVENTION 
     Gas turbine components are subjected to both thermally, mechanically and chemically hostile environments. For example, in the compressor portion of a gas turbine, atmospheric air is compressed to 10-25 times atmospheric pressure, and adiabatically heated to 800°-1250° F. (427° C.-677° C.) in the process. This heated and compressed air is directed into a combustor, where it is mixed with fuel. The fuel is ignited, and the combustion process heats the gases to very high temperatures, in excess of 3000° F. (1650° C.). These hot gases pass through the turbine, where airfoils fixed to rotating turbine disks extract energy to drive the fan and compressor of the turbine, and the exhaust system, where the gases provide sufficient energy to rotate a generator rotor to produce electricity. To improve the efficiency of operation of the turbine, combustion temperatures have been raised. 
     A processed gas turbine component and a method of processing a gas turbine component by welding without cracks inside a weld and/or an interface capable of operating with higher temperatures would be desirable in the art. 
     BRIEF DESCRIPTION OF THE INVENTION 
     According to an exemplary embodiment, a method of processing a component includes providing a base metal having a feature, the base metal having a base metal composition, a base metal thermal expansion coefficient, a base metal yield strength, and a base metal elongation, removing the feature to form a processed region, applying a first layer to the processed region, the first layer having a first filler, the first filler having a first filler composition, a first filler thermal expansion coefficient, a first filler yield strength, and a first filler elongation, and applying a second layer to the first layer, the second layer having a second filler, the second filler having a second filler composition, a second filler thermal expansion coefficient, a second filler yield strength, and a second filler elongation. The first filler thermal expansion coefficient is less than both the base metal thermal expansion coefficient and the second filler thermal expansion coefficient. The first filler yield strength is greater than the base metal yield strength and less than the second filler yield strength. The first filler elongation is greater than the base metal elongation and less than the second filler elongation. 
     According to another exemplary embodiment, a method of processing a component includes providing a base metal having a feature, the base metal having a base metal composition, a base metal thermal expansion coefficient, a base metal yield strength, and a base metal elongation, removing the feature to form a processed region, applying a first layer to the processed region, the first layer having a first filler, the first filler having a first filler composition, a first filler thermal expansion coefficient, a first filler yield strength, and a first filler elongation, and applying a second layer to the first layer, the second layer having a second filler, the second filler having a second filler composition, a second filler thermal expansion coefficient, a second filler yield strength, and a second filler elongation. The first filler composition includes by weight between about 1.0 percent and about 1.5 percent carbon, between about 42.5 percent and about 47.5 percent iron, and a balance of nickel, and wherein the second filler composition includes by weight up to about 0.1 percent carbon, about 20 percent to about 23 percent chromium, about 5.0 percent iron, about 1.0 percent cobalt, between about 8.0 percent and about 10.0 percent molybdenum, between about 20 percent and about 23 percent chromium, and a balance of nickel. 
     According to another exemplary embodiment, a processed component includes a base metal having a base metal composition, a base metal thermal expansion coefficient, a base metal yield strength, and a base metal elongation, a processed region, a first layer applied to the processed region, the first layer having a first filler, the first filler having a first filler composition, a first filler thermal expansion coefficient, a first filler yield strength, and a first filler elongation, and a second layer applied to the first layer, the second layer having a second filler, the second filler having a second filler composition, a second filler thermal expansion coefficient, a second filler yield strength, and a second filler elongation. The first filler thermal expansion coefficient is less than both the base metal thermal expansion coefficient and the second filler thermal expansion coefficient. The first filler yield strength is greater than the base metal yield strength and less than the second filler yield strength. The first filler elongation is greater than the base metal elongation and less than the second filler elongation. 
     Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  schematically shows a processed component according to an embodiment of the disclosure. 
     
    
    
     Wherever possible, the same reference numbers will be used throughout the drawings to represent the same parts. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Provided are a processed component and a method of processing a component having a weld without cracks inside the weld and/or cracks inside an interface of the weld. 
     Referring to  FIG. 1 , an exemplary processed component  100  includes a base metal  102 , a first layer  104  with a first filler, and a second layer  106  with a second filler. As used herein the term “layer” refers to a filler material deposited through welding. The processed component  100  is a metal component. In one embodiment, the processed component is a gas turbine component such as a blade, rotor, a diaphragm, a bucket, or dovetail. According to an exemplary process, the first layer  104  is applied to a surface deformity  108  (for example, a cavity, a crack, a chip, a hole, a fissure, or other suitable surface feature) in the base metal  102  of the component  100 . The second layer  106  is then applied on the first layer  104 . As will be appreciated, the second layer  106  may remain separate from the base metal  102  and/or may partially contact the base metal  102 , depending upon the complexity of the weld and the technique utilized by the welder. 
     The base metal  102  includes a base metal composition, a base metal thermal expansion coefficient, a base metal yield strength, and a base metal elongation. In an exemplary embodiment of the processed component  100 , the first layer  104  is positioned proximal to the base metal  102 . The first layer  104  has a first filler composition, a first filler thermal expansion coefficient, a first filler yield strength, and a first filler elongation. The second layer  106  is positioned proximal to the first layer  104 . The second layer  106  has a second filler composition, a second filler thermal expansion coefficient, a second filler yield strength, and a second filler elongation. 
     The first layer  104  and the second layer  106  are selected based upon one or more predetermined properties. For example, in one embodiment, the first layer  104  and the second layer  106  are selected in response to the base metal composition, the base metal thermal expansion coefficient, the base metal yield strength, the base metal elongation, and combinations thereof. For example, in one embodiment, to make the first layer  104 , a first filler metal is selected such that the first filler composition includes less carbon content, less iron content, and higher nickel content than a second filler for making the second layer  106 . In another embodiment, to make the first layer  104  and/or the second layer  106 , the first filler and/or the second filler are selected such that the first filler thermal expansion coefficient is less than both the base metal thermal expansion coefficient and the second filler thermal expansion coefficient. In another embodiment, to make the first layer  104  and/or the second layer  106 , the first filler and/or the second filler are selected such that the second filler yield strength is greater than both the base metal yield strength and the first filler yield strength. 
     The selection of the first filler to make the first layer  104  and/or the second filler to make the second layer  106  is based upon the specific identifiable and quantifiable relationships and/or differences between the base metal  102  and the first layer  104  and/or the second layer  106 . For example, in one embodiment, the first filler and/or the second filler is selected such that the difference in the thermal expansion range of the first filler and/or the second filler in comparison to the base metal  102  is a predetermined difference of thermal expansion. In this embodiment, the first filler thermal expansion coefficient is less than the base metal thermal expansion coefficient and the second filler thermal expansion coefficient is greater than the first filler thermal expansion coefficient. 
     In one embodiment, the predetermined difference of thermal expansion coefficient between the first filler to make the first layer  104  and the base metal  102  is between about 7.0 μm/m·K and about 8.0 μm/m·K (i.e., the value of the base metal thermal expansion coefficient minus the value of the first filler thermal expansion coefficient), 6.0 μm/m·K and about 9.0 μm/m·K, 5.0 μm/m·K and about 10.0 μm/m·K, at about 6.5 μm/m·K, at about 7.0 μm/m·K, at about 7.5 μm/m·K, or at about 8.0 μm/m·K. Additionally or alternatively, the first filler to make the first layer  104  has a thermal expansion coefficient between about 65 percent and about 75 percent lower than the base metal  102  (i.e., the value of the base metal thermal expansion coefficient minus the value of the first filler thermal expansion coefficient and all divided by the value of the base metal thermal expansion coefficient). 
     In one embodiment, the predetermined difference of the thermal expansion coefficient between the first filler to make the first layer  104  and the second layer  106  is between about 2.3 μm/m·K and about 3.3 μm/m·K (i.e., the value of the second filler thermal expansion coefficient minus the value of the first filler thermal expansion coefficient), between about 1.3 μm/m·K and about 4.3 μm/m·K, between about 1.8 μm/m·K and about 3.8 μm/m·K, at about 2.3 μm/m·K, at about 2.6 μm/m·K, or at about 2.9 μm/m·K. Additionally or alternatively, the first filler to make the first layer  104  has a thermal expansion coefficient between about 18 percent and about 26 percent lower than the second layer  106  (i.e., the value of the second filler thermal expansion coefficient minus the value of the first filler thermal expansion coefficient and all divided by the value of the second filler thermal expansion coefficient). 
     In one embodiment, the base metal  102  has a thermal expansion coefficient of about 17.6 μm/m·K, the first filler to make the first layer  104  has a thermal expansion coefficient of about 12.8 μm/m·K, the second filler to make the second layer  106  has a thermal expansion coefficient of about 10.2 μm/m·K, and combinations thereof. 
     In one embodiment, the first filler to make the first layer  104  and/or the second filler to make the second layer  106  is selected such that the difference in elongation of the first layer  104  and/or the second layer  106  in comparison to the base metal  102  is a predetermined difference of elongation. As used herein, the term “elongation” refers to the material extension during the tensile strength testing at a constant temperature. For example, elongation is measured extending a metal and comparing a length of the metal prior to being extended to an extended length of the metal at the point the metal fractures. In this embodiment, the first filler elongation is slightly above or below the base metal elongation and the second filler elongation is greater than the first filler elongation. 
     In one embodiment, the predetermined difference of elongation between the first layer  104  and the base metal  102  is between a value of about 32 percent and a value of about 36 percent (i.e., the value of the first filler elongation minus the value of the base metal elongation), at a value of about 34.5 percent (i.e., the value of the first filler elongation minus the value of the base metal elongation), between a comparative range of about 75 percent and about 85 percent (i.e., the value of the first filler elongation minus the value of the base metal elongation and all divided by the value of the first filler elongation), and/or at about 81 percent (i.e., the value of the first filler elongation minus the value of the base metal elongation and all divided by the value of the first filler elongation). 
     In one embodiment, the predetermined difference of elongation between the second filler to make the second layer  106  and the first filler to make the first layer  104  is between a value of about 29.5 percent and a value of about 36.5 percent (i.e., the value of the second filler elongation minus the value of the first filler elongation), at a value of about 33 percent (i.e., the value of the second filler elongation minus the value of the first filler elongation), or between a comparative range of about 69.5 percent and about 86 percent (i.e., the value of the second filler elongation minus the value of the first filler elongation and all divided by the value of the second filler elongation). 
     In one embodiment, the base metal  102  has an elongation of about 8.0 percent, the first filler to make the first layer  104  has an elongation between about 6 percent and about 13 percent, and the second filler to make the second layer  106  has an elongation of about 42.5 percent. 
     In one embodiment, the first filler to make the first layer  104  and/or the second filler to make the second layer  106  is selected such that the difference in the yield strength of the first filler and/or the second filler in comparison to the base metal  102  is a predetermined difference of yield strength. As used herein, the term “yield strength” refers to the resistance of a metal to stress at which a material begins to plastically deform. In this embodiment, the first filler yield strength is greater than the base metal yield strength, the second filler yield strength is greater than both the first filler yield strength and the base metal yield strength. 
     In one embodiment, the predetermined difference of yield strength between the first filler to make the first layer  104  and the base metal  102  is between about 15 Ksi and about 22 Ksi (i.e., the value of the first filler yield strength minus the value of the base metal yield strength), at about 18.5 Ksi (i.e., the value of the first filler yield strength minus the value of the base metal yield strength), between about 50 percent and about 73 percent (i.e., the value of the first filler yield strength minus the value of the base metal yield strength and all divided by the value of the base metal yield strength), and/or at about 61.5 percent (i.e., the value of the base metal yield strength minus the value of the base metal yield strength and all divided by the value of the base metal yield strength). 
     In one embodiment, the predetermined difference of yield strength between the second filler to make the second layer  106  and the first filler to make the first layer  104  is between about 23 Ksi and about 30 Ksi (i.e., the value of the second filler yield strength minus the value of the first filler yield strength), at about 26.5 Ksi (i.e., the value of the second filler yield strength minus the value of the first filler yield strength), between about 30 percent and about 40 percent (i.e., the value of the second filler yield strength minus the value of the first filler yield strength and all divided by the value of the second filler yield strength), and/or at about 35 percent (i.e., the value of the second filler yield strength minus the value of the first filler yield strength and all divided by the value of the second filler yield strength). 
     In one embodiment, the base metal  102  has a yield strength of about 30 Ksi, the first filler to make the first layer  104  has a yield strength of about 45 Ksi to about 52 Ksi, and/or the second filler to make the second layer  106  has a yield strength of about 75 Ksi. 
     In one embodiment, the base metal composition is a nickel-resist cast type D-2 within a composition range by weight of up to about 3.0 percent carbon, about 1.75 percent to about 3.00 percent silicon, about 0.70 percent to about 1.0 percent manganese, about 1.75 percent to about 2.5 percent chromium, about 73.5 percent iron, and a balance of nickel (for example, between about 18 percent to about 22 percent nickel). The nickel-resist cast type D-2 provides resistance to corrosion, erosion, and frictional wear up to temperatures of about 1400° F. (about 760° C.). 
     In one embodiment, the first filler composition is by weight between about 1.0 percent and about 1.5 percent carbon, between about 50 percent and about 55 percent nickel, and between about 42.5 percent and about 47.5 percent iron. In a further embodiment, the composition is by weight between about 1.2 percent carbon, about 53 percent nickel, and about 45.0 percent iron. 
     In one embodiment, the second filler composition has a composition range of up to about 0.1 percent carbon, about 20 percent to about 23 percent chromium, about 5.0 percent iron, about 1.0 percent cobalt, between about 8.0 percent and about 10.0 percent molybdenum, between about 20 percent and about 23 percent chromium, and a balance of nickel. 
     In one embodiment, the base metal composition and the first filler composition include about the same carbon content and nickel content, the first filler thermal expansion coefficient is less than both the base metal thermal expansion coefficient and the second filler thermal expansion coefficient, the first filler yield strength is greater than the base metal yield strength, but less than the second filler yield strength, and the first filler elongation is greater than both the base metal elongation and the second filler elongation. 
     While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.