Search Results for full density powder metallurgy

This article provides a basic introduction to the various aspects of full density powder metallurgy, including properties, applications, processing methods, and process parameters.

Superalloys are predominantly nickel-base alloys that are strengthened by solid-solution elements including molybdenum, tungsten, cobalt, and by precipitation of a Ni 3 (Al, Ti) type compound designated as gamma prime and/or a metastable Ni 3 Nb precipitate designated as gamma double prime. This article provides a discussion on the conventional processing, compositions, characteristics, mechanical properties, and applications of powder metallurgy (PM) superalloys. The conventional processing of PM superalloys involves production of spherical prealloyed powder, screening to a suitable maximum particle size, blending the powder to homogenize powder size distribution, loading powder into containers, vacuum outgassing and sealing the containers, and consolidating the powder to full density. PM superalloys include Rene 95, IN-100, LC Astroloy, Udimet 720, N18, ME16, RR1000, Rene 88DT, PA101, MERL 76, AF2-1DA, Inconel 706, AF115, and KM4. The article reviews specialized PM superalloy processes and technical issues in the usage of PM superalloys.

This article begins with a discussion on general powder metallurgy design considerations that assist in the selection of the appropriate processing method. It reviews powder processing techniques, conventional press-and-sinter methods, and full-density processes to understand the design restrictions of each powder processing method. The article provides comparison of powder processing methods based on their similarities, differences, advantages, and disadvantages. It concludes with a discussion on design issues for the components of powder processing technologies.

This article reviews various segments of the powder metallurgy (PM) process from powder production and powder processing through the characterization of the materials and their properties. It covers the processing methods for consolidating metal powders including options for processing to full density. The article outlines the freeform fabrication process, also known as additive manufacturing and describes finishing operations of PM parts. It concludes with information on the applications of PM parts.

The organizations that are most active in the development of standards for powder metallurgy (PM) are the American Society for Testing and Materials (ASTM), Metal Powder Industries Federation (MPIF), and International Standards Organization (ISO). This article presents the test method standards, materials standards, and material designation codes for PM materials. It provides information on the codes for structural parts, PM soft magnetic materials, PM self-lubricating bearings, metal injection molded materials, and powder forged materials.

This article focuses on the significant fundamental powder characteristics, which include particle size, particle size distribution, particle shape, and powder purity, followed by an overview of general and individual powder production processes such as mechanical, chemical, electrochemical, atomizing, oxide reduction, and thermal decomposition processes. It also covers the consolidation of powders by pressing and sintering, as well as by high density methods. Further emphasis is provided on the distinguishing features of powders, their manufacturing processes, compacting processes, and consolidated part properties. In addition, a glossary of powder metallurgy terms is included.

Consolidation of titanium powders at room temperature may be performed by low-cost conventional powder metallurgy processes. This article provides information on various consolidation methods, namely, die pressing, direct powder rolling, and cold isostatic pressing. It also describes the sintering of blended elemental powders, high-strength titanium alloys, and porous material as well as the sintering of titanium powders by microwave heating.

Direct powder rolling (DPR) is a process by which a suitable powder or mixture of powders is compacted under the opposing forces of a pair of rolling mill rolls to form a continuous green strip that is further densified and strengthened by sintering and rerolling. This article discusses the basic principle, process considerations, and advantages of DRP, and describes the application of this process in the manufacture of powder titanium and titanium alloy components. It further illustrates the complexity of the process and describes the benefits of using DRP in terms of economics and product quality.

Power metallurgy (PM) is a process of shaping metal powders into near-net or net shape parts combined with densification or consolidation processes for the development of final material and design properties. This article introduces the general considerations, models, and applications in the modeling of PM processes. It describes the PM process in terms of powder compaction and sintering. The article schematically illustrates powder injection molding for the production of plastic parts and describes PM process models such as discrete-element model (DEM), linear continuum model, and nonlinear continuum model. It concludes with information on the application of press and sinter modeling to practical problems in PM.

This article discusses the fracture and fatigue properties of powder metallurgy (P/M) materials depending on the microstructure. It describes the effects of porosity on the P/M processes relevant to fatigue and fracture resistance. The article details the factors determining fatigue and fracture resistance of P/M materials. It reviews the methods employed to improve fatigue and fracture resistance, including carbonitriding, surface strengthening and sealing treatments, shot-peening, case hardening, repressing and resintering, coining, sizing, and postsintering heat treatments. Safety factors for P/M materials are also detailed.

This article focuses on the fractography features of the conventional powdered metal (PM) process for ferrous powders. It discusses porosity, which is one of the inherent features present in components produced by conventional press-and-sinter processes, and green cracks, which are the most common fracture issue in conventional PM processes. It explains the effect of post-sintering operations. The article also presents the common ferrous powder metallurgy materials.

Successful application of forging and hot pressing involves careful consideration of powder preparation and forming process parameters. This article describes the important process features for powder forging and hot pressing, along with specific applications and materials used.

This article discusses the pressing and sintering of various refractory metal powders for the production of intermediate products as well as special cases of finished products. The metal powders considered include tungsten, molybdenum, tantalum, niobium and their alloys, as well as rhenium.

This article discusses metal powder processing via hot isostatic pressing (HIP) and HIP cladding when metal powders are being employed in the cladding process. It traces the history of the process and details the equipment, pressing cycle, and densification mechanisms for HIP. The article describes the available process routes for fabricating products using HIP and the steps involved in the production of a part via direct HIP of encapsulated gas-atomized spherical powder. It concludes with information on the microstructures of 316L stainless steel HIP powder metallurgy valve body and a list of the mechanical properties of several powder metallurgy alloys.

This article describes the capabilities, limitations, advantages, and disadvantages of the powder metallurgy (PM) gear manufacturing process. It discusses the types of gears that can be produced by PM and presents the design guidelines for PM gears. The article provides information on gear tolerances and performance of PM gears. It also explains various procedures to inspect and test the mechanical properties, dimensional specifications, and surface durability (hardness).

This article focuses on the mechanical properties, production of titanium powder metallurgy (P/M) compacts, namely, blended elemental (BE) compacts and prealloyed (PA) compacts. It explains the postcompaction treatments of titanium P/M compacts, including heat treatment, and thermochemical processing. The article talks about the applications of titanium P/M products, namely, BE and PA products. It concludes with a short note on the future trends in titanium P/M technology.

Stainless steels are primarily alloys of iron and chromium. They are grouped into five families, primarily based on their microstructure: ferritic, austenitic, martensitic, duplex, and precipitation hardening. Three out of the five families of stainless steels, namely, austenitic, ferritic, and martensitic, are well suited for manufacture via conventional powder metallurgy (PM) processes. This article presents the iron-chromium partial phase diagram to illustrate the changes in the temperature range when pure iron is alloyed with chromium. It describes AISI and UNS numbering systems, which are used as an identification system for stainless steels. The article tabulates the material designations of stainless steels in accordance with the Metal Powder Industries Federation. It also details the characteristics and chemical composition of wrought and PM stainless steels.

Certain metal products can be produced only by powder metallurgy; among these products are materials whose porosity is controlled. Successful production by powder metallurgy depends on the proper selection and control of process variables: powder characteristics; powder preparation; type of compacting press; design of compacting tools and dies; type of sintering furnace; composition of the sintering atmosphere; choice of production cycle, including sintering time and temperature; and secondary operations and heat treatment. When the application of a powder metallurgy part requires high levels of strength, toughness, or hardness, the mechanical properties can be improved or modified by infiltration, heat treatment, or a secondary mechanical forming operation such as cold re-pressing or powder forging. The article also discusses the effect of the secondary processes on P/M mechanical properties.

High-temperature sintering of ferrous components continues to be important in the powder metallurgy (PM) industry. Improvements in both production rates and properties are possible as sintering temperatures increase above 1120 deg C. This article provides an overview of the different various stages of the sintering process and the physical, chemical, and metallurgical phenomena occur within the mass of metal powder particles. It discusses the four advantages of high-temperature sintering of various ferrous PM materials: improved mechanical properties, improved physical properties, development of liquid phase, and ability to sinter active elements in alloy steels. The article also provides information on three sources of process control requirements, namely, the powder blend, green density, and sintering conditions.