SS 347 vs SS304 – What's the Difference?
Jul 07, 2025
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Difference between 304 and 347 stainless steel?
SS 347 and SS304 are both austenitic stainless steels, but they serve different roles in engineering and industrial applications. The main difference lies in the presence of niobium in SS 347, which makes it more suitable for high-temperature and welded applications where resistance to intergranular corrosion is essential.
SS 347 vs SS 304 stainless steel: key difference
| SS 304 | SS 347 | |
|---|---|---|
| S30400 | S34700 | |
| Moderate (needs post-weld treatment) | ||
| High-Temperature Resistance | Up to 870℃ (short term) | Excellent for continuous use up to 900℃ |
SS 347 vs SS 304 stainless steel: Chemical Composition
| SS 304 (%) | SS 347 (%) | |
|---|---|---|
| 18.0 – 20.0 | 17.0 – 19.0 | |
| 8.0 – 10.5 | 9.0 – 13.0 | |
| <= 0.08 | <= 0.08 | |
| - | >= 10 × C (typically 0.3 – 1.0%) | |
| <= 2.0 | <= 2.0 |
SS 347 vs SS 304:Mechanical Properties
| SS 304 | SS 347 | |
|---|---|---|
| >= 515 | >= 515 | |
| Yield Strength 0.2% (MPa) | >= 205 | >= 205 |
| Elongation (% in 50 mm) | >= 40 | >= 40 |
| <= 201 | <= 201 | |
| ~193 | ~193 |
SS 347 vs SS 304:Physical Properties
| SS 304 | SS 347 | |
|---|---|---|
| 7.93 | 7.93 | |
| Thermal Conductivity at 100℃ (W/m·K) | ~16.2 | ~14.6 |
| ~500 | ~500 | |
| ~72 | ~78 | |
| Thermal Expansion Coefficient (µm/m·K, 20–100℃) | ~17.2 | ~16.0 |
| 1400–1450 | 1398–1446 | |
| Non-magnetic | Non-magnetic |
304 vs 347 high-temperature resistance
Due to the niobium (Nb) stabilization treatment, SS347 can inhibit the precipitation of grain boundary carbides at 870℃, maintain creep resistance and intergranular corrosion resistance, and can still maintain 70% of the room temperature yield strength at 593℃.
while SS304 is prone to precipitate chromium carbides above 425℃, resulting in weakening of grain boundaries, and the maximum operating temperature is 650℃, and the yield strength retention rate at the same temperature is only 50%. Therefore, 347 is more suitable for high-temperature scenes such as furnace components and heat exchangers, while 304 is limited to medium-temperature environments such as food processing.
Need Help Choosing Between SS 304 and SS 347?
SS 304 and SS 347 stainless steel sheets, pipes, tubes, and fittings in accordance with ASTM, ASME, and EN standards. Contact our technical team for:Material test certificates (MTCs),Custom sizing or cutting,Advice on high-temperature material selection!
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