Gas nitriding and ferritic nitrocarburizing have seen tremendous growth. Today, it continues to accelerate as more uses are being found, especially in the growing electric vehicles (EV) sector. This success is due to the ability to control protective white layers consistent with the needs of an automotive engineer. Steels and cast irons are still the materials of choice for many applications and the nitrided layer is wellknown for its tribological features (some would say even more than three) which include wear resistance, lubricity, and a low coefficient of friction. Corrosion resistance in particular has become an important advantage and depends on white layer formation and quality. The white layer (known as the compound zone) consists of two iron nitrides, epsilon (Fe 2-3 [N]) and gamma prime (Fe 4 N). In addition, the epsilon layer can contain varying amounts of iron carbides and/or iron carbonitrides, Fe 2-3 [C]. This paper will focus mainly on the how’s and why’s of white layer: how to control its composition and properties; and how to minimize it, if required. Just as importantly, some applications of how the EV component engineers have found uses for this important steel treatment are discussed, including brake rotors.

Integral quench furnaces combine the benefits of low-pressure vacuum carburizing (LPC) with atmosphere oil quenching. This paper discusses key milestones in the development of integral quench furnaces and the advantages they provide in annealing, normalizing, and hardening applications.

Gas nitriding has been performed in many ways with many variations over the years (using NH 3 only, NH 3 + dissociated NH 3 , and NH 3 + N 2 ). Practical heat treating today demands lower costs and gas and energy consumption. With the challenges of ammonia storage, its costs and emissions, the ZeroFlow process reduces ammonia gas consumption and still offers the same capability to affect the nitrided layer, resulting in lower emissions of ammonia and greenhouse gases. Prior analysis has shown that ZeroFlow control allows control of not only the nitriding potential, but also phase composition of the nitrided layer, its thickness and the constituents of the atmosphere used for nitriding. Tremendous experience via actual commercial production has proven that this method of gas nitriding, and the atmosphere used, still allows for precision in controlling growth kinetics of the nitrided layer. The impact on the ammonia consumption and emissions is significant.