One Minute Mentor: High-Performance Line

The continuous heat treatment of tool steel is applied to low- or medium-alloyed carbon steel strips as well as martensitic stainless steels. The described lines produce high-quality strip with respect to uniform structure, flatness, and bright surface finish. High quenching rates are necessary, especially for plain carbon steels. Cooling gradients of up to 600 K/s are possible in a molten lead-bismuth quench. Because two-stage quenching technology provides considerable advantages over quenching in oil, this method has been adopted worldwide. It is also possible to achieve isothermal transformation to bainite and pearlite using a molten metal quench, so this type of hardening and tempering line is extremely versatile.

The configuration of a high-performance line involves an entry and exit section of the strip handling equipment. The hardening section consists of the austenitizing furnace, the molten metal quench or hydrogen quench, and a martensite cooler.

For more information, click on the link below (subscription required). Then scroll to Figure 10. R Schneider; R. Mesquita; W Schützenhöfer, Distortion in Tool Steels, ASM International, 2014 

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ALD develops a new powder recycling process for a sustainable circular economy

ALD Vacuum Technology, Germany, has developed an additive manufacturing solution, the EBuild 850 that can process powder with a wide distribution, enabling it to be used not only in industrial-scale part production, but also in powder recycling efforts. 

Using selective electron beam melting to create powder-filled ingots, ALD achieves an unprecedented build rate of over 1000 cm³ per hour. These ingots can be seamlessly converted into new powder, for example in ALD’s EIGA Premium systems, promoting a sustainable circular economy.

ALD’s approach not only reduces waste, but also offers versatile options for downstream processes. The powder-filled solid cased ingots are much safer to handle and process than loose powder. This flexibility increases the overall efficiency of the recycling process and enables integration into established processing routes.

By adopting ALD’s innovative approach, industries can now achieve economical production while contributing to a circular economy. ALD remains committed to driving sustainable practices within the industrial sector, paving the way for a greener future.

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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