UNS S29108 Cr-Mn-N Steel Round Bar

Product Description

UNS S29108 is a high-nitrogen, austenitic stainless steel often referred to by its trade name Nitronic® 19 (or simply "19-18" in some contexts).

It is a member of the nitrogen-strengthened Cr-Mn-N family, specifically engineered to provide a combination of high yield strength and excellent corrosion resistance. Within the spectrum of materials you have been exploring, S29108 is a modern alternative to the 18/18 series (like P900 or Datalloy 2), offering comparable non-magnetic stability with distinct corrosion characteristics.

Technical Profile: UNS S29108

This grade utilizes exceptionally high Nitrogen levels to expand the austenite phase field and increase mechanical strength without the need for high Nickel content.

Key Performance Attributes

• Exceptional Yield Strength: In its annealed state, S29108 has roughly double the yield strength of standard 300-series stainless steels. When cold-worked, it can reach levels exceeding 1100 MPa.

• Pitting Resistance: With its high Chromium and Nitrogen content, it provides excellent resistance to pitting and crevice corrosion, often outperforming Alloy 316L in chloride-heavy environments.

• Low Magnetic Permeability: It remains strictly non-magnetic ($\mu_r < 1.01$), even after severe cold working or at cryogenic temperatures. It does not undergo the martensitic transformation that can make standard stainless steels slightly magnetic after being formed.

• Resistance to Galling: Like other Nitronic alloys, S29108 has superior metal-to-metal wear characteristics compared to common stainless steels, making it ideal for moving parts.

Primary Applications

UNS S29108 round bars are utilized where structural integrity and magnetic transparency are non-negotiable:

• Oil & Gas Exploration: Specifically for Non-Magnetic Drill Collars (NMDC) and Measurement While Drilling (MWD) tool bodies.

• High-Strength Fasteners: Bolts and studs in naval applications or medical imaging (MRI) equipment.

• Aerospace: Landing gear components and bushings that require high strength and corrosion resistance.

• Power Generation: Retaining rings and specialized hardware for high-speed rotors.

Comparison: S29108 vs. P900 (1.3816)

While they occupy the same space in the "18-18" nitrogen-strengthened category, S29108 is generally produced to meet ASTM/UNS standards, whereas P900 is often tied to European SEL (1.3816) specifications.

Processing and Machining

• Machinability: Similar to the other grades in this lineage, S29108 is difficult to machine. It is highly abrasive and work-hardens instantly. Use rigid setups, heavy feeds, and slower speeds.

• Cold Working: This material is almost exclusively strengthened through cold deformation (cold drawing or cold rolling). It cannot be hardened by heat treatment.

• Solution Annealing: Typically performed at 1040°C – 1120°C followed by rapid cooling to ensure the most stable austenitic structure.

Given your sequence of queries—starting with the lower-chromium 1.3815 and moving through P900, Datalloy 2, and now S29108—it appears you are looking for the optimal balance of Nitrogen-driven strength and Chromium-driven corrosion resistance. S29108 represents the "gold standard" for non-magnetic structural applications in corrosive environments.