Which Titanium Grades Are Suitable for Plasma Nitriding?

redesiht
4 hours ago
2 min read

Typically, we don’t like to provide "black and white" answers. If our years in the industry have taught us anything, it’s that there are no one-size-fits-all solutions in metallurgy. Every workshop owns its own know-how, and whether by following or breaking the "handbook recipes," engineers succeed in optimizing the mechanical properties of titanium in exceptional ways, tailored to the rigorous demands of modern industry.

However, when discussing the plasma nitriding of titanium alloys, we must start with the fundamentals:

Industrial Classification of Titanium

Titanium used in technical applications is grouped into three main alloy types based on their metallurgical structure, which determines their response to surface hardening heat treatments:

Alpha (α) Titanium	This corresponds to ASTM Grade 2, also known as Commercially Pure (α) or CP Titanium. It possesses high oxidation resistance and excellent performance at elevated temperatures. However, it does not respond well to quenching or aging. Therefore, it is primarily recommended for cold-formed parts or components exposed to constant heat without cyclic loading, such as molds, housings, or heat exchangers.
Beta (β) Titanium	This group includes ASTM Grades 19, 20, 21, or 38. These alloys respond to quenching and aging, making them ideal when complex workability followed by a subsequent heat treatment is required. They are commonly used for anchors, structural supports, or components requiring a high degree of hardening.
Alpha-Beta (α-β) Titanium	Alloyed with aluminum and vanadium, these offer an excellent balance of strength, toughness, and machinability. They are ideal for withstanding heavy loads and cyclic stresses while maintaining integrity even in biological or marine environments.

Technical table of the industrial classification of titanium by IONHEAT, detailing alloy types,Alpha, Beta, and Alpha-Beta, along with their corresponding ASTM grades (2, 5, 23, 19, 20, 21, and 38). The infographic maps alloying elements, mechanical characteristics, and heat treatment notes to typical engineering applications, such as heat exchangers, structural supports, and medical components. — [Download this table to compare titanium types by grade, alloying elements, and heat treatment considerations.]

Titanium Selection for Nitriding

The objective of nitruring titanium by plasma is primarily to increase surface wear resistance, maintain corrosion resistance, and protect the biocompatibility of titanium. For this purpose, the most common grades in the industry are:

Titanium Grade 5:

The Ti-6Al-4V (α-β) alloy represents more than 50% of the titanium used worldwide. It is the benchmark for improving surface hardness in Grade 5 titanium within the aerospace and mechanical engineering sectors.

Titanium Grade 23:

The ELI (Extra Low Interstitials) version of Grade 5 is critical in medicine and dentistry. Nitriding improves its performance against friction without compromising its chemical stability in long-term contact with biological tissues.

It is important to clarify that this process is not an external coating (like PVD). Instead, it is a thermochemical diffusion process where nitrogen atoms penetrate the metal's crystal lattice. The result is the formation of extremely hard titanium nitrides (TiN y Ti₂N) that eliminate the most critical limitation of this material: its poor resistance to wear caused by friction or sliding contact.

When is plasma nitriding the right choice for the surface treatment of titanium?

If you want to dive deeper into the technical parameters, we invite you to download the ebook: Yes, Plasma Nitriding Works for Titanium. Here’s When and Why.

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