What Is 1.4307 Stainless Steel Yield Strength? EN 10088 and ASTM A240 Values Explained

Short Answer: 175 MPa Minimum in the Solution-Annealed Condition

For 1.4307 stainless steel, the yield strength most often quoted on mill certificates and in design calculations is the 0.2 % proof strength, Rp0.2, with a minimum of 175 MPa for product up to the section sizes covered by EN 10088 in the solution-annealed condition. The 1.0 % proof strength, Rp1.0, is specified as 210 MPa minimum. Tensile strength falls in the 500 to 700 MPa band, and elongation is 45 % minimum in the longitudinal direction. Grade 1.4307 is the EN designation for the low-carbon austenitic alloy also known as 304L or UNS S30403, with the composition written as X2CrNi18-9.

Under the ASTM system the same alloy is covered by ASTM A240, which sets a minimum yield strength of 170 MPa and minimum tensile strength of 485 MPa, with 40 % minimum elongation. The small difference between 175 MPa and 170 MPa comes from the different definition of the test section and product form, not from a different material.

Composition and Property Basis

Item	1.4307 (X2CrNi18-9)
Carbon, % max	0.030
Chromium, %	17.5 - 19.5
Nickel, %	8.0 - 10.5
Manganese, % max	2.00
Yield strength Rp0.2, min	175 MPa
Yield strength Rp1.0, min	210 MPa
Tensile strength Rm	500 - 700 MPa
Elongation A, min (longitudinal)	45 %
Hardness, max	215 HB

Because the alloy is austenitic and cannot be strengthened by heat treatment, its strength is set by composition and by the amount of cold work in the product. That is why proof strength is quoted as a minimum for the annealed condition: cold-rolled strip, drawn wire and cold-formed sections will read higher, sometimes substantially so.

Yield Strength at Elevated Temperature

Proof strength falls steadily as temperature rises, and design codes apply a reduction factor accordingly. Representative minimum 0.2 % proof strength values in the solution-annealed condition are about 145 MPa at 100 °C, about 118 MPa at 200 °C, about 100 MPa at 300 °C, about 89 MPa at 400 °C and about 81 MPa at 500 °C. The corresponding 1.0 % proof strength values are higher at every temperature, starting near 180 MPa at 100 °C.

The practical consequence is that a component sized on the room-temperature yield value will be overstressed in elevated-temperature service, even though the tensile strength remains adequate. Creep becomes relevant above roughly 500 °C, where the material also becomes susceptible to carbide precipitation, and stabilised grades are then preferred.

How 1.4307 Compares with 1.4301

The two grades share chromium and nickel ranges and differ almost entirely in carbon: 1.4307 is limited to 0.030 % and 1.4301 to 0.07 %. The higher carbon of 1.4301 gives it a slightly higher proof strength, commonly quoted around 190 MPa against 175 MPa for 1.4307, together with the same 500 to 700 MPa tensile range. What 1.4301 does not provide is weldability without post-weld treatment: above roughly 425 °C the higher carbon content allows chromium carbides to form at grain boundaries, and those chromium-depleted zones corrode preferentially in a wet or acidic environment. For welded vessels, pipework and any component that will see a corrosive medium, 1.4307 is the safer selection despite the slightly lower guaranteed strength. For non-welded, general-purpose parts and for internal components where a little extra strength helps, 1.4301 is the economical choice.

Corrosion, Magnetism and Welding

Grade 1.4307 has no deliberate molybdenum addition, so its pitting resistance equivalent number, calculated as Cr + 3.3 Mo + 16 N, lands around 18 to 19 for typical compositions. It is resistant to fresh water, steam and many organic and mildly acidic media, but it is not a chloride grade: pitting and crevice corrosion appear in chloride-bearing service, and stress corrosion cracking is a risk in warm chlorides. The alloy is non-magnetic when annealed, and becomes slightly magnetic after cold working. It is welded with 308L filler metal, classified under EN 1.4316 or AWS A5.9, and the low carbon content means welded joints retain their resistance to intergranular corrosion without annealing.

Frequently Asked Questions

Q: What is the yield strength of 1.4307 stainless steel?
A: The minimum 0.2 % proof strength is 175 MPa for solution-annealed product under EN 10088, with a 1.0 % proof strength of 210 MPa minimum, tensile strength of 500 to 700 MPa and minimum elongation of 45 %. ASTM A240 specifies a minimum yield strength of 170 MPa for the same alloy.

Q: Does cold working increase the yield strength of 1.4307?
A: Yes. The alloy work-hardens rapidly, so cold-rolled strip, drawn wire and cold-formed profiles have proof strengths well above the annealed minimum, along with reduced ductility. Certificate values reflect the actual product condition.

Q: What is the difference between 1.4307 and 1.4301?
A: Carbon content. Grade 1.4307 is capped at 0.030 % and grade 1.4301 at 0.07 %. Grade 1.4301 offers slightly higher proof strength, around 190 MPa against 175 MPa, while 1.4307 resists intergranular corrosion after welding because there is insufficient carbon to form chromium carbides.

Q: Is 1.4307 magnetic?
A: It is essentially non-magnetic in the annealed condition. Cold working forms a small amount of martensite, so formed or drawn parts can show a weak magnetic response, which is normal for the alloy.

Q: How much does 1.4307 yield strength drop at high temperature?
A: Representative minima in the annealed condition fall from 175 MPa at room temperature to about 145 MPa at 100 °C, about 100 MPa at 300 °C and about 81 MPa at 500 °C. Design calculations should use the value for the actual service temperature.

Q: Which filler metal is used for welding 1.4307?
A: Low-carbon 308L filler, designated 1.4316 in EN classification or ER308L under AWS A5.9. The low carbon content of both the base metal and the filler prevents carbide precipitation in the heat-affected zone.