Nitronic® 50 is an austenitic stainless steel produced with an increased nitrogen content that improves its strength and corrosion resistance. It is widely referred to as XM19 - the generic alloy designation in ASTM A276 and ASTM A479 - and also as UNS S20910 or DIN 1.3964. Nitrogen, chromium and molybdenum together raise its Pitting Resistance Equivalent Number (PREN) to greater than 34, similar to S32205 duplex stainless steel and well above low-alloyed grades.

It is available in two conditions. Annealed material has a minimum yield strength of 55ksi / 380N/mm2; in the hot-rolled condition, also known as high-strength, it achieves a minimum yield strength of 105ksi / 725N/mm2.

Nitronic 50 vs Nitronic 60

Although Nitronic 60 was, like Nitronic 50, originally developed by Armco (now AK Steel Corporation) and also benefits from an increased nitrogen content, its composition, properties and typical applications are quite different. Nitronic 60 (Fermonic® 60, UNS S21800) contains higher additions of silicon and manganese, which are less commonly used in stainless steels. This gives it excellent galling and wear resistance, so it is used mainly for items such as connectors and couplings, despite lower corrosion resistance and strength than Nitronic 50.

Nitronic 50 vs 17-4 PH

17-4 PH is a martensitic stainless steel named for its nominal 17% chromium and 4% nickel content, with strength induced by precipitation hardening through heat treatment - hence the PH. The double-aged H1150D condition is perhaps the most widely specified, giving a minimum yield strength of 105ksi / 725N/mm2. That matches Nitronic 50HS, but its corrosion resistance is substantially lower, with a PREN of greater than 16 only.

Cost and selection

Nitronic 50 is more expensive than duplex and super duplex stainless steels, than standard austenitic grades such as Alloy 304L and Alloy 316L, and than 17-4 PH. This reflects its higher content of more expensive alloying elements, particularly nickel, so it is specified only where its properties are worth the premium - for example improved impact toughness against duplex alloys, particularly at lower temperatures, or ease of fabrication.

We carry a comprehensive stock of XM19 / S20910 in both annealed and hot-rolled condition as round bar, in diameters from 1" (25.4mm) to 10" (254mm).

Common applications for Nitronic 50

  • Valve fittings, particularly stems, thanks to the excellent alloy toughness
  • Marine applications, including rod rigging using cold drawn lengths, tie-downs and fittings
  • Pump shafts
  • Sucker rods for oil rigs
  • Fasteners
Grade Condition Min yield strength PREN
Nitronic 50 (XM19) Annealed 55ksi / 380N/mm² >34
Nitronic 50 (XM19) Hot Rolled (HS) 105ksi / 725N/mm² >34
17-4 PH H1150D 105ksi / 725N/mm² >16