What is Nitriding?
Plasma technology is primarily for stainless steel and other low alloy steels which are not suitable for a “standard” thermal heat treatment process. The process uses a Plasma discharge of Hydrogen and Nitrogen gases to heat the steel surfaces and to supply nitrogen ions for nitriding. Plasma nitriding is an established and successful process particularly important for precision machined parts. It is a heat treatment process that is used to improve wear-resistance, surface hardness and material fatigue.
What are the benefits of Nitriding?
Usually steels are beneficially treated with plasma nitriding. This process permits the close control of the nitrided microstructure, allowing nitriding with or without compound layer formation. Not only is the performance of metal parts enhanced, but working lifespans also increase, and so do the strain limit and the fatigue strength of the metals being treated. For instance, mechanical properties of austenitic stainless steel like resistance to wear can be significantly augmented and the surface hardness of tool steels can be doubled.
A plasma nitrided part is usually ready for use. It calls for no machining, or polishing or any other post-nitriding operations. Thus the process is user-friendly, saves energy since it works fastest, and causes little or no distortion.
Plasma nitriding is often coupled with Physical Vapor Deposition (PVD) process and labeled Duplex Treatment, with enhanced benefits. Many clients prefer to have a plasma oxidation step combined at the last phase of processing to produce a smooth layer of oxides which is resistant to wear and corrosion.
What Materials can be treated?
Examples of easily nitridable steels include the SAE 4100 4300, 5100, 6100, 8600, 8700, 9300 and 9800 series, UK aircraft quality steel grades BS 4S 106, BS 3S 132, 905M39 (EN41B), austenitic stainless steels, some tool steels such as AISI H13 (1.2344) and AISI P20 (1.2311) for example and certain cast irons. Ideally, steels for nitriding should be in the hardened and tempered condition, requiring nitriding to take place at a lower temperature than the last tempering temperature. A fine-turned or ground surface finish is best. Minimal amounts of material should be removed post nitriding to preserve the surface hardness.
Nitriding alloys are alloy steels with nitride-forming elements such as aluminum, chromium, molybdenum and titanium. Therefore, plasma-nitriding can also be applied to aluminium, titanium and nickel alloys to increase surface hardness making these materials more durable and wear-resistant.
What are examples of Industries / Products?
Nitriding is used in many industries and fields, including but not limited to: Aerospace, Dye- & Toolmakers, Automotive, Medical, Gearboxes, Plastic- & Aluminium Extrusion, Valves, etc.
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