JOM
The design and construction of the decorative bell capital of the 1,600 year old Delhi iron pillar attests to the high degree of skill of the ancient Indian blacksmiths in working iron. Detailed visual observations clearly establish that the decorative bell capital is not a single piece of metal, but is composed of separate pieces that have been individually constructed by forge welding. A critical...
Woodruff Imberman is a management consultant with Imberman and DeForest.
Large-diameter SiC fibers have been prepared using chemical vapor deposition by radio-frequency heating; this article focuses on the evolution of fiber strength in the preparatory and secondary treatment stages of this preparation. Fibers that are produced by this process show high tensile strength (>3,500 MPa) for various gauge lengths. Furthermore, these fibers exhibit good strength retention...
A stochastic numerical approach was developed to model the formation of grain structure and secondary phases during the solidification of nickel-based alloy 718 remelt ingots. The significance of the present stochastic approach is that the simulated phases can be directly compared with actual phases from experiments at two different scales: grain characteristics can be visualized at the macroscale,...
Remelting is performed to facilitate the production of clean, fully dense, homogeneous castings of superalloys and aerospace titanium alloys and is crucial to the defect-free production of these important materials. Modern electroslag remelting and vacuum arc remelting control systems are closed-loop, single input-single output systems that oversimplify the physical properties of the processes; the...
Ann D. Helms is a product metallurgist with the Billet Division of Allvac, an Allegheny Teledyne Company. She is the advisor to JOM from the High Temperature Alloys Committee of the TMS Structural Materials Division. Christopher O’Brien is a metallurgical engineer with Allvac.
Vacuum arc remelting and electroslag remelting processes are used to produce large (five tonne) ingots of nickel-based superalloys, titanium alloys, and other high-value-added alloys. The remelting processes provide controlled solidification conditions capable of producing extremely uniform chemistry and microstructure; however, the consequences of a single defect are potentially so great, that process...
Defect reduction is one of the most important goals in continuing research to improve remelting technologies, such as vacuum arc remelting, electroslag remelting, or hearth melting (plasma or electron beam), of specialty alloys. Ingot defects may originate from several sources in these processes, such as foreign materials in the melt stock or electrode, drop-in material from the furnace interior,...
In recent years, it has become apparent that bath smelting may be a suitable technology for treating wastes. Technologies developed by Molten Metal Technology, Ausmelt, Mintek, Techtronics, and the University of Wollongong utilize molten baths of metal and slag to process metal-containing wastes. This paper discusses the similarities and differences between these processes, focusing particularly on...
This article outlines a method for developing a quality-based cost model for the design of new electronic systems and products. The model incorporates a methodology for determining a cost-effective design margin allocation for electronic products and systems and its impact on manufacturing quality and cost. A spreadsheet-based cost estimating tool was developed to help implement this methodology in...