One Minute Mentor: Plasma Nitriding Equipment

Cold-walled (double-walled water-cooled) systems were the first generation of plasma nitriding furnaces. This technology is also a vacuum-based process but employs the principle of glow discharge to provide energy for heating and nitriding at one time. Therefore, the independent control of the temperature stability and the nitriding intensity is not possible because both processes are using the same energy source—the plasma.

The hot-wall plasma nitriding furnaces, the next generation of cold-wall ion nitriding systems, are mainly used and built now. This system ensures optimal nitriding quality by fulfilling the highest demands on temperature and nitriding process control. The big advantage of this technology is the separation of the control of the heating and the plasma nitriding parameters. The heating and temperature control of hot-wall plasma nitriding furnaces is realized by several independent heating/cooling zones, which guarantees optimal temperature homogeneity

For more information, click on the link below (subscription required). Then scroll to Figure 26.

R Schneider; R. Mesquita; H. Altena; T. Müller; P. Seemann, Processes and Furnace Equipment for Heat Treating of Tool Steels, ASM International, 2014, https://doi.org/10.31399/asm.hb.v04d.a0005958

Shape memory alloy reinforcement for strengthening of RCC structures

Raisoni College of Engineering, India, has published a critical review of significant performance and safety issues that arise from the deterioration of reinforced concrete (RC) structural components brought on by ageing processes and high stress occurrences. 

Shape memory alloys (SMAs), one of the options for restoring such components, have special qualities including recovering inelastic strain when unloaded (super elasticity) or heated (shape memory effect, SME). To lessen permanent deformations into RC constructions, super elasticity and SME of SMA bars can be used. The stiffness and strength of RC structures can also be improved by the addition of SMAs, allowing them to withstand loads of high intensities with minimal damage. 

Despite the wide range of studies done on the applications of SMAs in structures, a comprehensive analysis of the present state, key results, potential drawbacks, and future contemplation of SMA bars for the reinforcement of RC structures is lacking in the literature. 

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Mark Saline receives MPIF distinguished service award

Gasbarre, Dubois, PaA, announced that Mark Saline, president of Gasbarre Thermal Processing Systems, is a recipient of the 2023 MPIF Distinguished Service to Powder Metallurgy (PM) Award that recognizes individuals who have actively served the North American PM industry for at least 25 years.The award is selected by the Metal Powder Industries Federation’s (MPIF) Awards Committee.

Over 70 nominated individuals were on the ballot for review by the past 10 years of Distinguished Service Award recipients, as well as the MPIF Board of Governors and Boards of Directors of the MPIF trade associations. Mark Saline will receive his award during PowderMet 2023 in Las Vegas. Mark has been well established in the Powder Metallurgy industry for many years. His PM involvement includes teaching students at the PM Sintering Seminar, sitting on the MPIF Program Committee, judging the PM Design Excellence Awards, he has written several publications on processing in continuous furnaces, and he provides input in organizations such as the Center for Powder Metal Technology, Powder Metal Equipment Association, and the Association for Metal Additive Manufacturing. Mark will also serve at the Conference Technical Chair-Person for PowderMet 2024 in Pittsburgh.

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Evolution on the microstructure and mechanical properties of a new multicomponent near-Alpha Titanium Alloy after rolling and heat treatments

Beijing University of Technology, China, presented the microstructure and mechanical properties of a new type of multi-component near-α titanium alloy sheet after rolling, 700°C aging, and 800°C aging in a new paper.

 The results show that the strength of the alloy after aging at 700°C increases from 1156 MPa to 1304 MPa, respectively, but decreases to 1246 MPa with the aging temperature increasing. The ductility of the alloy aged at 700°C is lower than that of the rolled state, but the ductility increases slightly with the aging temperature increasing. The effect of aging heat treatment on the microstructure and precipitation behavior of alloy plates has been studied and compared with alloys before aging. 

After heat treatment, the content of primary α decreases from 25% to 5%, respectively. Two kinds of silicide precipitate at different positions, with the large-size spherical silicide being (Ti, Zr, Nb)5Si3, and the small-size fusiform silicide being (Ti, Zr, Nb)6Si3, respectively. Ti3Al was precipitated in the primary α phase, during the aging process. The silicides exhibit the strengthening effect on the alloy, but the effect weakens when the silicides grow up. The loss in ductility is mainly attributed to the precipitation of the α2 phase after aging treatment. However, ductility is improved after applying higher aging temperatures as the size of the α2 phase becomes smaller, and the distribution of them tends to become dispersed.

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A ‘green’ Seco/Warwick vacuum furnace for wind power plants

Seco/Warwick, Meadville, Pa., has been chosen by a recognized manufacturer of wind power plants to deliver a vertical vacuum furnace designed to perform low-pressure carburizing for the large structural elements (gearboxes) used in wind power plants. 

The solution on order combines the advantages of two technologies: atmospheric and vacuum processing. The furnace is designed for low-pressure carburizing oversized parts, made possible due to a very large, vertical heating chamber, while the furnace pit structure saves space in the production facility. The Pit-LPC technology is a modern alternative to atmosphere carburizing. Its main advantage is the ability to carry out efficient and effective carburizing in a much shorter time than in atmospheric furnaces. The vacuum processing solution provides more than twice the productivity, and consequently lower process costs and a quick investment return.

The main advantage of this furnace is the ability to open the furnace at process temperature at the end of the cycle. This is the advantage of atmospheric furnace technology implemented within a vacuum furnace. This type of solution combines the advantages of an atmospheric furnace with the advantages of a vacuum furnace, which include: elimination of the oxidation effect at the grain boundary, process purity, and heating uniformity. The product solves the problem of high energy and process gas consumption by the partner’s old furnaces, and shortens the carburizing process, which significantly improves efficiency and production costs.

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Lindberg/MPH ships rod overbend box furnace to the manufacturing industry

Lindberg/MPH, Mich., has announced the shipment of a rod overbend box furnace with powered load/unload table to the manufacturing industry. This heat-treating furnace has a maximum temperature rating of 2000°F and a load capacity of 900 lbs. 

The workspace dimensions of the furnace are 24” W x 36” D x 18” H and it is designed for air atmosphere applications. The box furnace features an automated actuator to flip the push/pull mechanism on the load table to eliminate the operators need to manually flip it into push position. This option allows the push/pull head to retract from the furnace once the work grid is in the furnace chamber and increase operator safety by removing the need to reach into the hot furnace with a hook to flip the push/pull head and.

The furnace chamber is heated with a radiant heating system the utilizes heavy gauge alloy rod over-bend heating elements mounted along the side-walls and the floor. The furnace temperature is controlled by an Allen Bradley ControlLogix Programmable Logic Controller that includes digital setpoint and display. A Honeywell DC2500 high limit controller disconnects the power to the heating elements and sounds an audible alarm if the temperature exceeds desired set-point. 

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Artificial neurons based on semiconductor technology

Artificial neural networks are a key technology in the domain of AI and machine learning. Many applications need the rapid parallel processing of vast amounts of data—with correspondingly high energy demand. A new project in which physicist Dr. Andreas Tittl plays an important role, is seeking to develop an energy-saving alternative through a specially tailored combination of materials science and photonics.

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Squeezing a diamond sandwich produces useful data

Scientists have searched, for decades, for a way to apply the exceptional analytical capabilities of neutrons to materials under pressures approaching those surrounding the Earth’s core. These extreme pressures can rearrange a material’s atoms, potentially resulting in interesting new properties.

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Contributor Corner: David W. Rosen, Ph.D.

Dr. David W. Rosen is a Principal Research Scientist at the Institute for High Performance Computing and the Singapore Institute for Manufacturing Technology, both A*STAR institutes in Singapore. He was a professor in the School of Mechanical Engineering at the Georgia Institute of Technology for many years.

Dr. Rosen has played a critical role in the development and publishing of ASM International’s growing content selection on additive manufacturing (AM). He recently served as co-Division Editor and author for ASM Handbook, Volume 24A: Additive Manufacturing Design and Applications (select articles now available in the Digital Library; print edition scheduled to publish later in 2023). He also authored several articles for ASM Handbook, Volume 24: Additive Manufacturing Processes (2020).

Additionally, Dr. Rosen has held faculty and research positions at the Singapore University of Technology & Design. He received his Ph.D. at the University of Massachusetts in mechanical engineering. His research interests include computer-aided design, AM, and design methodology with a specific interest in design for AM. He is a Fellow of ASME and is the recipient of the 2013 Solid Freeform Fabrication Symposium, International Freeform and Additive Manufacturing Excellence (FAME) Award, and is a co-author of a leading textbook on AM.

In the standards community, Dr. Rosen chairs the ASTM F42 subcommittee on design for AM. He was awarded the ASTM Award of Merit and promoted to Fellow of ASTM in 2022.

Lindberg/MPH ships mesh belt conveyor furnace for use with powdered metal

Lindberg/MPH, Mich., has announced the shipment of an electrically heated, full muffle, mesh belt conveyor furnace. This furnace is designed for treating pressed powdered material.

The furnace is designed for applications with a maximum process temperature of 1000° C (1832° F) that utilize a nitrogen or clean dry filtered air process atmosphere. The unit is configured with 9 temperature control zones and includes a water-cooling section. The conveyor system features a 14 inch wide mesh belt with belt stop alarm to provide an audible and visual indication in case of a conveyor stoppage.

There are purge chambers at the entrance and exit of this conveyor furnace. In these chambers purge gas flows from perforated plenum chambers above and below the belt and exhaust stacks with adjustable butterfly valves are located at the inner ends of each chamber. Load and unload tables at the entrance and exit of the conveyor provide ease of product transfer for the operator.

The furnace zone temperatures are controlled by Eurotherm controllers. These controllers have advanced PID control with variable overshoot inhibition. A hi-limit Eurotherm controller guards against over temperature conditions in each zone of temperature control.  A visual and audible alert and removal of power to the heating element occur in the event the monitor temperature exceeds a desired set point. 

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One Minute Mentor: Salt Bath Nitrocarburizing

Salt bath nitrocarburizing is usually performed at temperatures between 560 and 580 °C (1040 to 1075 °F) in cyanate- and carbonate-containing salts with traces of cyanides and furnaces similar to those used for the nitrocarburizing of mechanical compounds. These conditions fit well with the usual tempering temperatures of hot-work tool steels, which form the main field of application of salt bath nitrocarburizing in tooling with treatment times of 15 min to 2 h.

 To guarantee a good reproducible nitriding performance, the cyanate content must be kept at approximately 35% to achieve a full ε-nitride compound layer, which today is usually done by adding a regenerator. The advantages of salt bath nitrocarburizing can be found in the very homogeneous temperature distribution, the fast formation of thick compound layers that give good tribological and corrosion properties, its high flexibility, and he fact that it does not require that any special attention be given to passivation effects. Extrusion dies are regularly treated several times during use to restore the nitride layer at areas of heavy wear.

More recently special salt compositions were developed for lower nitrocarburizing temperatures, which are essential for cold-work tool steels that do have lower tempering temperatures.

For more information, click on the link below (subscription required). Then scroll to Figure 21

R Schneider ; R. Mesquita ; H. Altena ; T. Müller ; P. Seemann,Processes and Furnace Equipment for Heat Treating of Tool Steels, ASM International, 2014, https://doi.org/10.31399/asm.hb.v04d.a0005958