Method of manufacturing a weld-free apparatus for connection of dissimilar metals using functionally graded compositionally control powder metallurgy and hot isostatic processing methods
a technology of compositionally controlled powder metallurgy and manufacturing method, which is applied in the direction of manufacturing tools, heat treatment apparatus, furnaces, etc., can solve the problems of weak creep-strength carbon-free zone or deleterious type i or ii carbide formation, and failures may still occur prematurely
Inactive Publication Date: 2013-05-16
ELECTRIC POWER RES INST INC
View PDF7 Cites 7 Cited by
- Summary
- Abstract
- Description
- Claims
- Application Information
AI Technical Summary
Benefits of technology
The present invention provides a method to create a weld-free apparatus for connecting dissimilar metals with a smooth transition between different metals. This is achieved by creating a mold that replicates the inverse of the apparatus, introducing metal powders into the mold to form a transition region between different metals, and then consolidating and melting the metal powders in a high temperature, high pressure inert gas atmosphere. The resulting apparatus has significant benefits in terms of strength and durability.
Problems solved by technology
Unfortunately with exposure time at temperature, many of these DMW joints have a finite life of 7-12 years before they have to be replaced due to a carbon activity gradient leading to the formation of a creep-strength weak carbon-free zone or deleterious Type I or II carbides.
However, even with the higher quality shop welded Dutchman, failures may still occur prematurely due to the difference in coefficient of expansion.
Method used
the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View moreImage
Smart Image Click on the blue labels to locate them in the text.
Smart ImageViewing Examples
Examples
Experimental program
Comparison scheme
Effect test
Embodiment Construction
[0011]Referring to the drawings, a modified apparatus, such as a Dutchman, formed in accordance with an embodiment of the invention is illustrated in FIG. 1 and shown generally at reference numeral 10.
[0012]The current invention eliminates the DMW altogether. To create the modified Dutchman 10, functionally graded compositionally controlled powder metallurgy / hot isostatic pressing (HIP) practices are employed. With this process, the composition of the Dutchman tube 10 is gradually transitioned from the ferritic tube composition (carbon-, CrMo, or CSEF steel) to the austenitic SS composition over a 1-3 inch (25.4-76.2 mm) region of the 12 inch (304.8 mm) long Dutchman tube 10. The gradual transition results in a smoother transition in the tube 10 CTE from one alloy to another and reduces overall stresses.
[0013]Equally important, carbon migration problems (and the concurrent loss in creep strength) often associated with DMWs are eliminated entirely and a smooth transition between tubi...
the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More PUM
| Property | Measurement | Unit |
|---|---|---|
| length | aaaaa | aaaaa |
| temperature | aaaaa | aaaaa |
| pressure | aaaaa | aaaaa |
Login to View More
Abstract
A method of manufacturing a weld-free apparatus for use in the connection of dissimilar metals includes the steps of providing a mold designed to replicate a reverse of the apparatus, introducing a low alloy, ferritic steel composition atomized powder into a first portion of the mold, introducing a series of atomized powders incrementally into a second portion of the mold to form a transition region between the ferritic steel composition and an austenitic stainless steel composition, and introducing an austenitic stainless steel composition atomized powder into a third portion of the mold. The method further includes the step of consolidating and melting the atomized powders in a high temperature, high pressure inert gas atmosphere to form the apparatus.
Description
BACKGROUND OF THE INVENTION[0001]This application claims the benefit of Provisional Application No. 61 / 489,501 filed on May 24, 2011.[0002]This application relates to a method of manufacturing a weld-free apparatus for use in the connection of dissimilar metals, and more particularly, to a method of providing a weld-free tube Dutchman for use in the connection of dissimilar metals in a power plant environment.[0003]Conventional fossil power plants employ thousands of dissimilar metal tube welds (DMWs) throughout economizers, superheaters, and reheat assemblies. DMWs are used to provide a transition between carbon, chromium-molybdenum (CrMo), or a creep-strength enhanced ferritic (CSEF) steel tubes to an austenitic stainless steel or nickel based tubes. This transition is necessary as certain parts of the boiler experience higher temperature operation and / or corrosive conditions. The DMW is commonly performed using a nickel-based weld filler metal that provides a coefficient of therm...
Claims
the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More Application Information
Patent Timeline
Login to View More Patent Type & Authority Applications(United States)
IPC IPC(8): B22F7/02B22D23/06
CPCB22F3/15B22F2999/00B22D23/06B22F7/02B22F5/106B22F2207/01C22C33/0285
Inventor GANDY, DAVID W.COLEMAN, KENT K.SHINGLEDECKER, JOHN
Owner ELECTRIC POWER RES INST INC