Datasheet updated

2024-01-11 10:29
(supersedes all previous editions)

General description

Sanmac® 304/304L is an austenitic chromium-nickel steel with improved machinability.


  • ASTM: 304, 304L
  • UNS: S30400, S30403
  • EN Number: 1.4301, 1.4307
  • EN Name: X 5 CrNi 18-10, X 2 CrNi 18-9
  • W.Nr.: 1.4301
  • JIS: SUS304


Product standards

  • EN 10088-3, EN 10088-5 (dimensions up to 250 mm)
  • EN 10272, EN 10222-5, (dimensions ≥ 180 mm), AD-2000-W2
  • ASTM A479, A276
  • Chemical composition and mech. properties acc. ASTM A182


  • TÜV AD-Merkblatt W0/TRD 100
  • Pressure Equipment Directive (2014/68/EU)
  • Ü-Zeichen
  • JIS Approval for Stainless Steel Bars


  • Status according to EN 10 204/3.1

Chemical composition (nominal)

Chemical composition (nominal) %
C Si Mn P S Cr Ni
≤0.030 0.3 1.8 ≤0.040 ≤0.030 18.5 8.5


SANMAC® 304/304L is used for a wide range of industrial applications.

Industrial categories Typical applications
Chemical industry Flanges
Food industry Valves
Petrochemical industry Fittings
Pulp & paper industry Couplings
Nuclear industry Rings
Bolts and Nuts

Corrosion resistance

General corrosion

Sanmac® 304/304L has good resistance in:

  • organic acids at moderate temperatures
  • salt solutions, e.g. sulfates, sulfides and sulfites
  • caustic solutions at moderate temperatures
  • oxidizing acids like nitric acid

Stress corrosion cracking

Austenitic steels are susceptible to stress corrosion cracking. This may occur at temperatures above about 60°C (140°F) if the steel is subjected to tensile stresses and at the same time comes into contact with certain solutions, particularly those containing chlorides.

In applications demanding high resistance to stress corrosion cracking we recommend the austenitic-ferritic steel Sanmac® SAF 2205, see datasheet S-8702-ENG.

Intergranular corrosion

Sanmac® 304/304L has a low carbon content and therefore good resistance to intergranular corrosion.

Pitting and crevice corrosion

The Sanmac® 304/304L grade is relatively low alloyed and therefore it may be sensitive to pitting and crevice corrosion even in solutions of relatively low chloride content. Molybdenum-alloyed steels have better resistance and the resistance improves with increasing molybdenum content.

Gas corrosion

Sanmac® 304/304L can be used in

  • air up to 850°C (1560°F)
  • steam up to 750°C (1380°F
  • synthesis gas (ammonia synthesis) up to about 550°C (1020°F)

Creep behavior should also be taken into account when using the steel in the creep range. In flue gases containing sulphur, the corrosion resistance is reduced. In such environments the steel can be used at temperatures up to 600–750°C (1110–1380°F) depending on service conditions. Factors to consider are whether the atmosphere is oxidizing or reducing, i.e. the oxygen content, and whether impurities such as sodium and vanadium are present.

Forms of supply

Finishes and dimensions

Sanmac® 304/304L bar steel is stocked in a large number of sizes. The standard size range for stock comprises 20-450 mm and in inch sizes 3/4-14", see pocket card S-02909. Round bar is supplied in solution annealed and peel turned condition.


Bars are delivered in random lengths of 3-7 m, depending on diameter.

Diameter Height of arch, Typical value
mm mm/m
20 - 70 1
> 70 2
Tolerances, mm-sizes
Diameter Tolerances
mm mm
20-35 -0/+0.15
40-45 -0/+0.16
50-95 -0/+0.19
75-95 -0/+1.00
100-265 -0/+1.50
290-350 -0/+2.00

Tolerances for the inch-sizes are in accordance with ASTM A-484

Surface conditions Ra, Typical value Size, diameter
µm mm
Peeled and polished 1 20-300
Peel turned 2 >300

Heat treatment

Sanmac® 304/304L bars are delivered in solution annealed condition. Billets are delivered in hot-worked condition. If another heat treatment is needed after further processing the following is recommended.

Solution annealing

1040–1100°C (1900–2010°F), rapid cooling in air or water.

Hot working

Hot working should be carried out at a material temperature of 900-1200°C (1650-2190°F), cooling in air or in water. If additional heat treatment is needed it should be carried out in accordance with the recommendations given for heat treatment.

Mechanical properties

Bar steel is tested in delivery condition.

At 20°C (68°F)

Metric units
Proof strength Tensile strength Elong. Contr. HB
Rp0.2a) Rp1.0a) Rm Ab) Z
MPa MPa MPa % %
≥205 ≥230 515-680 ≥45 ≥50 ≤215
Imperial units
Proof strength Tensile strength Elong. Contr. HB
Rp0.2a) Rp1.0a) Rm Ab) Z
ksi ksi ksi % %
≥29.5 ≥33.5 74.5-98.5 ≥45 ≥50 ≤215

1 MPa = 1 N/mm2
a) Rp0.2 and Rp1.0 corresponds to 0.2% offset and 1.0% offset yield strength, respectively.
b) Based on L0 = 5.65√S0 , where L0 is the original gauge length and S0the original cross-section area.

Impact strength

Due to its austenitic microstructure, SANMAC® 304/304L has very good impact strength both at room temperature and at cryogenic temperatures.

Tests have demonstrated that the steel fulfils the requirements (60 J (44 ft-lb) at -196 oC (-320 oF)) according to the European standards EN 13445-2 (UFPV-2) and EN 10272.

At high temperatures

Metric units
Temperature Proof strength Tensile strength
Rp.02 Rp1.0 Rm
°C MPa MPa MPa
min. min. min.
100 155 190 450
200 127 155 400
300 110 135 380
400 98 125 380
500 92 120 360
Imperial units
Temperature Proof strength Tensile strength
Rp.02 Rp1.0 Rm
°F ksi ksi ksi
min. min. min.
200 23.1 28.1 66.1
400 18.3 22.4 57.9
600 15.7 19.3 55.1
800 14.0 17.9 54.3
1000 13.1 17.4 48.9

Physical properties

Relative magnetic permeability < 2,5

Density: 7.9 g/cm3, 0.29 lb/in3

Thermal conductivity
Temperature Temperature
°CW/m °C°FBtu/ft h °F
20 15 68 8.5
100 16 200 9.5
200 18 400 10.5
300 20 600 12
400 22 800 13
500 23 1000 14
600 25 1200 15
700 26 1300 15
Specific heat capacity
Temperature Temperature
°CJ/kg °C°FBtu/lb °F
20 475 68 0.11
100 500 200 0.12
200 530 400 0.13
300 560 600 0.13
400 580 800 0.14
500 600 1000 0.14
600 615 1200 0.15
700 625 1300 0.15
Thermal expansion 1)
Temperature Temperature
°CPer °C°FPer °F
30-100 16.5 86-200 9.5
30-200 17 86-400 9.5
30-300 17.5 86-600 10
30-400 18 86-800 10
30-500 18.5 86-1000 10
30-600 18.5 86-1200 10.5
30-700 19 86-1400 10.5

1) Mean values in temperature ranges (x10-6)

Modulus of elasticity 1)
Temperature Temperature
20 200 68 29.0
100 194 200 28.2
200 186 400 26.9
300 179 600 25.8
400 172 800 24.7
500 165 1000 23.5

1) x103


Sanmac is our trademark for the Alleima machinability concept. In Sanmac materials, machinability has been improved without jeopardizing properties such as corrosion resistance and mechanical strength.

The improved machinability is owing to:

  • optimized non-metallic inclusions
  • optimal chemical composition
  • optimized process and production parameters

Detailed recommendations for the choice of tools and cutting data regarding turning, thread cutting, parting/grooving, drilling, milling and sawing are provided in the brochure S-029-ENG.

The diagram shows the ranges within data should be chosen in order to obtain a tool life of minimum 10 minutes when machining austenitic Sanmac materials (304/304L, 316/316L). The ranges are limited in the event of low feeds because of unacceptable chip breaking. In the case of high cutting speeds, plastic deformation is the most dominant cause of failure. When feed increases and the cutting speed falls, edge frittering (chipping) increases significantly. The diagram is applicable for short cutting times. For long, continuous cuts, the cutting speeds should be reduced somewhat.

[bild] Figure 1. Machining chart Sanmac® 304/304L.

The lowest recommended cutting speed is determined by the tendency of the material to stick to the insert (built-up-edge), although the integrity of insert clamping and the stability of the machine are also of great significance.

It is important to conclude which wear mechanism is active, in order to optimize cutting data with the aid of the diagram.

Turning of Sanmac® 304/304L, 316/316L

Recommended insert and cutting data (starting values)

Insert Geometry Grade Cutting data
Cutting speed Application
mm/rev m/min
MF GC2015 0.15 250 Finishing, copy turning
MM GC2015 0.30 225 Medium machining
MM GC2025 0.30 195 Medium-to-rough machining under less stable conditions


The weldability of SANMAC® 304/304L is good. Suitable methods of fusion welding are manual metal-arc welding (MMA/SMAW) and gas-shielded arc welding, with the TIG/GTAW method as first choice.

Since this material is alloyed in such a way to improve its machinability, the amount of surface oxides on the welded beads might be higher compared to that of the standard 304/304L steels. This may lead to arc instability during TIG/GTAW welding, especially welding without filer material. However, the welding behavior of this material is the same as for standard 304/304L steels when welding with filler material.

For SANMAC® 304/304L, heat input of <2.0 kJ/mm and interpass temperature of <150°C (300°F) are recommended. Preheating and post-weld heat treatment are normally not necessary.

Recommended filler metals

TIG/GTAW or MIG/GMAW welding

ISO 14343 S 19 9 L / AWS A5.9 ER308L (e.g. Exaton 19.9.L)

MMA/SMAW welding

ISO 3581 E 19 9 L R / AWS A5.4 E308L-17(e.g. Exaton 19.9.LR)

Disclaimer: Recommendations are for guidance only, and the suitability of a material for a specific application can be confirmed only when we know the actual service conditions. Continuous development may necessitate changes in technical data without notice. This datasheet is only valid for Alleima materials.