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. 

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

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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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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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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One Minute Mentor: Vacuum Furnaces

The demands on vacuum-hardening technology have changed in recent decades. One of the most important considerations that must be met is the accomplishment of highest dimensional stability with optimal microstructural properties and minimal change of the surface of the workpieces. 

Minimizing exposure to air during the heat treatment by reducing the quantity of oxygen in a heat treatment furnace, as with creating a vacuum, is an excellent method for preventing changes in surface appearance and chemical composition.

Suppliers of modern vacuum furnaces are further faced with new demands, such as increasing quenching speed to improve microstructural and mechanical properties by reducing grain size, and enhancing hardness and toughness and/or reducing distortion due to the hardening process. Furthermore, quality standards such as AMS 2750d or North American Die Casting Association (NADCA), which describe temperature homogeneity or quenching speeds and resulting and needed workpiece properties, had a significant effect on furnace design and process control.

For more information, click on the link below (subscription required). Then scroll to Figure 14

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