The aim of the present research work was to investigate tribological performance and potential of Ni-based self-lubricating claddings for high temperature forming of lightweight alloys. Laser claddings included in this investigation were based on Ni-matrix with the incorporation of 5 wt% silver and 10 wt% MoS2 as solid lubricant precursors. Tribological evaluation and testing was performed by Load- Scanner to simulate hot forming process and results compared to high performance hot work tool steel. To simulate hot forming process of forging, wire drawing and extrusion, tests were done at room and elevated temperatures (150°C and 300°C) against typical light-weight alloys, including AISI 316L stainless steel, 6xxx series Al alloy and Ti6Al4V Ti alloy and results evaluated in terms of coefficient of friction vs. load, critical loads for galling initiation and volume of adhered work material. Results show that self-lubricated claddings with incorporated MoS2 and Ag as solid lubricants in general provide lower and more stable friction as well as improved galling resistance in high temperature forming of lightweight alloys. Positive effect of self-lubricating claddings intensifies with forming temperature, degree of plastic deformation and work material tendency to galling.

Gas carburizing with quenching is one of the most useful heat treatment processes for steel parts. However, after quenching distortion is still occurs. The nitriding and nitrocarburizing are the surface hardening heat treatment methods with low distortion, but these methods require the long treating time to obtain a thick hardened layer. Austenitic nitriding and quenching (ANQ) solves these problems. In ANQ process, nitrogen is infiltrated into the steel parts in austenite phase, and they are quenched to harden. The ANQ process can also be applied to cheap low carbon steel such as the Cold Rolled Carbon Steel Sheet. In this study, the effect of ANQ on mechanical properties was examined. For infiltrating the nitrogen into the steel parts, the steel parts were heating to 750°C or higher in an ammonia atmosphere and heating to 750°C or higher in a nitrogen glow discharge. After the ANQ process, hardness profiles, structure, nitrogen and carbon concentration profiles were observed. Also, distortion, tribological properties, impact value and fatigue strength were examined. The effective case depth, which is treated by ANQ, is larger than the effective case depth of gas nitrocarburizing for same period of time. Distortion of ANQ is much smaller than that of gas carbonitriding, and it is almost equal with that of gas nitrocarburizing. The seizure load is same as with other surface hardening heat treatment processes. The wear loss of ANQ is a lower, in the amount of about 1/2 that of the carbonitrided specimen and 1/3 that of the gas nitrocarburized specimen. The ANQ is an effective heat treatment process for parts which require wear resistance. The tempering softening resistance is improved by nitrogen infiltration. ANQ also improves the impact value and fatigue strength.

The purpose of this study is to clarify the mechanical properties of the expanded austenite (S phase) formed in austenitic stainless steel (ASS). A small thin rolled plate of SUS304 with 0.5 mm thickness was used as test sample. The test sample was nitrided by active screen plasma nitriding (ASPN) at low processing temperature of 400 °C and 450 °C during 4 h processing time. S phase was formed on the surface of the test sample. The surface hardness of ASPN sample was higher than that of untreated sample. Furthermore, tensile tests and fracture surface observations revealed that the tensile strength was also improved compared to untreated samples.

This study investigates the heat treatment response and microstructure evolution of high-carbon steels for additive manufacturing. Moreover, the role of nitrogen as an interstitial alloying element is addressed. Stainless steel 440C, cold-work D2, hot-work H13, and T15 high-speed tool steel overspray powders from spray forming were investigated. The thermal behavior of these materials was examined using a thermal analyzer that combines calorimetry and thermogravimetry. Additionally, interstitial alloying with nitrogen was performed in-situ to understand its influence on thermal behavior. The (near-)equilibrium nitrogen solubility in 440C and D2 in contact with flowing N 2 gas was recorded as a function of temperature through the interval 1200 to 800 °C. The microstructure of the steel powders was characterized by light optical microscopy and X-ray diffraction. The potential of nitrogen alloying and the importance of optimized heat treatment protocols are emphasized with respect to high-carbon steels in additive manufacturing applications.

Copper is expected to be increasingly used in electric vehicle components because of its high electrical and thermal conductivity. On the other hand, copper has the disadvantage of low fatigue strength compared to structural members such as steel and aluminum alloys. Therefore, the peening treatment is used in this study to increase the strength of copper. However, the projectile used in conventional peening treatments is much harder than copper, which may lead to deterioration of surface properties. Therefore, we decided to use a resin particle peening treatment that uses soft resin particles. For the projectile material, we used particles made from crushed walnut, apricot, and peach, which are natural material particles. Ceramic particles were used for comparison. Hardness measurements revealed that the near-surface hardness increased even when resin particles were used. In addition, compressive residual stresses were observed on the surface. Fatigue tests revealed that the fatigue strength improvement effect was higher than that of nontreated materials or hard particles. These results indicate that the resin particle peening treatment is an effective method for strengthening copper.

Liquid nitrocarburizing is a well-known surface treatment when it comes to tribological parts and systems. The surface layers formed through liquid nitrocarburizing processing (compound layer and diffusion zone) make it possible to combine the corrosion, wear, and fatigue resistance properties of the treated materials (mainly ferrous alloys, from low-carbon to high-alloy steels and even cast iron) while enhancing their tribological behavior. Based on its worldwide presence, its continuous improvement and high industrial maturity, HEF Groupe’s Liquid Nitrocarburizing is the technology ready for future with its CLIN 4.0 program and it ambitious ECOCLIN program which allow the recycling of wastes from nitriding installations and their transformation into directly reusable consumables. That is why HEF’s liquid nitrocarburizing is proven to be not only an alternative to other surface treatments (such as Chromium plating) on both technical aspects and price competitiveness but also a real solution answering the current environmental challenges. Thanks to the implementation of Life cycle Assessment methods, HEF’s liquid nitrocarburizing continuously improve its sustainability and continuously lower its impacts on global resources, making it an iterative routine to decrease environmental impact on all resources (Energy, water, raw materials,…)

Anti-wear, anti-galling and scratch resistance are well-known properties associated with FNC processes. The marked demand for expansion of the scope of processes in equipment available, has led to the development of tailored FNC process for application to low alloyed steel, and alloyed steel. The process had to be oxygen free, as the equipment is also applied in expanded austenite processes for corrosion resistant alloys. Utilizing our mass flow controller equipped furnaces the tight control of the parameters is possible resulting in high repeatability and a consistent compound layer formation. The process has been applied to a number of different alloys, showing good results for unalloyed steels and steels in quenched and tempered condition.