Alloy N30 - UNS S20400

UNS S20400

Typical Inventory

Plate, Coil

Product Description

N30 is a nitrogen-strengthened stainless steel developed for applications requiring a good level of aqueous corrosion resistance combined with good toughness and economy. N30 Stainless Steel provides approximately 50% higher yield strength than Type 304L and, therefore, may allow lighter gages to further reduce costs. N30 Stainless Steel work hardens rapidly while retaining good ductility. Unlike other nitrogen-strengthened stainless steels, N30 Stainless Steel is subject to magnetic transformation when cold worked.

General Data

  • Excellent mechanical properties at both extremely low and extremely high temperatures.
  • Outstanding resistance to pitting, crevice corrosion and intercrystalline corrosion.
  • Almost complete freedom from chloride induced stress corrosion cracking.
  • High resistance to oxidation at elevated temperatures up to 1050°C.
  • Good resistance to acids, such as nitric, phosphoric, sulfuric and hydrochloric, as well as to alkalis makes possible the construction of thin structural parts of high heat transfer.


N30 Stainless Steel offers significantly higher strength than Type 304 and potential for applications requiring good resistance to aqueous and atmospheric corrosion resistance combined with good toughness and economy.

Specific potential applications include automotive hose clamps, safety belt anchors, truck and bus frames, water supply and control structures, sewage treatment plant structures, bulk solids handling equipment, magnetic ore separator screens, coal buckets and hopper cars.

Stainless steels have served successfully in many structural components in the transportation industry. Bus space frames and bumpers take advantage of the excellent fabricability and high strength and toughness of stainless. Tensilized N30 Stainless Steel has been used in rapid transit structurals where the strength-to-weight ratio of up to three times that of carbon steel has improved operating efficiency. Rear frames of refrigerated trucks are easily welded and formed from N30 Stainless Steel, resulting in protective units that can withstand impact blows without cracking. Shipboard container structurals use stainless steel successfully because carbon steel becomes scuffed and rusts wherever the paint is damaged.

Common Specifications

The typical properties listed on page one can be provided in rounds, sheet, strip & plate. We have the equipment to produce small quantities in special sizes to meet our customers’ specific needs.

ASME SA 240, ASTM A 240


C Cu Mn Ni N Si Cr
Max 0.03% 1% 9% 3% 0.3% 1% 17%
Min 7% 1.5% 0.15% 15%

Mechanical Properties

Thickness in. (mm) Annealing Temperature F (C) Direction Ultimate Tensile ksi (MPa) Yield Strength ksi (MPa) Elong. % in 2 in. Hardness (Rockwell B)
0.124 (3.15) 1950 (1066) Longitudinal 117.7 (811) 54.0 (372) 52.0 93.5
0.064 (1.62) 2050 (1121) Longitudinal 100.0 (689) 53.8 (370) 58.5 93.0
Transverse 103.1 (711) 53.5 (368) 58.0 93.0
0.032 (0.81) 1950 (1066) Longitudinal 121.9 (840) 55.0 (379) 54.0 94.0
Transverse 119.7 (825) 54.4 (375) 55.0 94.0

Effect of Cold Work on Ferrite Number

Unlike the other NITRONIC alloys, N30 will undergo magnetic transformation due to cold reduction. This magnetism is the result of forming deformation martensite with cold work. This martensite increases the strength, work hardening rate, and abrasion resistance of the alloy.

% Cold Work Ferrite Number*
0 0
10 3
20 10
30 21
40 27

* As determined from a Ferritescope by Fisher Technology. The Ferritescope measures the % magnetic phase. Ferrite Number is therefore proportional to the amount of martensite present.

Effect of Cold Reduction on N30
Effect of Cold Reduction on N30
Typical engineering stress strain curves for N30
Typical Engineering Stress-Strain Curves

Wear Resistance

N30 has outstanding corrosive wear resistance under many different siding codintions. The stainless steels as a class are much more abrasion resistant than abrasion resistant (AR) steels under even mildly corrosive conditions. N30 is more cost effective than Types 409 and 304, which are typically used in wet abrasive applications.

Corrosive Wear of Alloy and Stainless Steels - fig 3
Corrosive Wear of Alloy and Stainless Steels - fig 3
Corrosive Wear of Alloy and Stainless Steels - fig 4
Corrosive Wear of Alloy and Stainless Steels - fig 4

Corrosion Resistance

N30 Stainless Steel exhibits good corrosion resistance to a variety of media. Pitting resistance, as measured by tests in 10% FeCl3 solution, is better than Type 304. In sulfuric acid and hydrochloric acid, N30 is much better than Types 409 and 410 and approaches Type 304 in more dilute solutions. Typical laboratory test data obtained on these alloys are shown in Table 10. Atmospheric corrosion resistance is shown in Figure 5.

N30 vs 304 corrosion protection comparison
N30 vs 304 corrosion protection comparison


Early experience with stainless shows good welding characteristics. It can be fusion welded with the usual arc welding processes employed for austenitic stainless steels. N30 provides superior ductility and toughness, as well as resistance to weld cracking without the need for preheating or postheating, as most martensitic and heavygage ferritic stainless steels require. A small quantity of ferrite will form in autogenous N30 stainless welds to minimize any hot cracking sensitivity. Arc welding parameters more closely approximate those of the other NITRONIC grades (e.g., slower weld travel, hotter shielding gas for GTAW - Ar + 5% H2 or He), rather than the standard austenitic stainless steels. Standard AWS austenitic stainless fillers or the newly included AWS A5.9 and A5.4 NITRONIC fillers (209, 240, 219) can be selected for any particular application.

Effect of Temp on the Impact Toughness of N30, 304, 409
Effect of Temp on the Impact Toughness of N30, 304, 409