Stainless steel 1.4301 vs 1.4401: Corrosion resistance

Corrosion Resistance Comparison: Stainless Steels 1.4301 vs. 1.4401

Stainless Steels 1.4301 vs. 1.4401:Chemical Composition 

	1.4301 (AISI 304)	1.4401 (AISI 316)
	17.5–19.5%	16.5–18.5%
	8.0–10.5%	10–13%
		2.0–2.5% (critical for corrosion resistance)
	Less than or equal to 0.07%	Less than or equal to 0.07%
	19–21 (moderate pitting resistance)	26–30 (significantly improved pitting resistance)

 

2. Corrosion Resistance in Key Environments

2.1 Chloride-Containing Environments (e.g., Seawater, Salt Solutions)

1.4301:

Performs well in low-concentration chlorides (e.g., fresh water, food contact) but is susceptible to

Salt spray test (ASTM B117) lifespan: ~1000 hours in 5% NaCl solution before visible corrosion.

1.4401:

Pitting potential (ASTM G48) is ~300–500 mV higher than 1.4301, indicating a more stable passive film against Cl⁻ attack.

 

2.2 Acid/Alkaline Environments

1.4301:

Non-oxidizing acids (e.g., sulfuric, hydrochloric acid): Only resistant to dilute solutions; high-concentration acids cause corrosion.

1.4401:

Non-oxidizing acids: Significantly better resistance than 1.4301 due to Mo; suitable for sulfuric/phosphoric acid processing (e.g., reactor vessels).

: Similar to 1.4301 but more stable in hot, concentrated alkalis.

2.3 High-Temperature and Oxidizing Environments

1.4301:

Short-term service up to 870 degree ; long-term exposure (420–870 degree ) may cause carbide precipitation, leading to intergranular corrosion.

Good oxidation resistance for general high-temperature use (e.g., kitchen appliances).

1.4401:

Wider temperature range (short-term 950 degree , long-term 800 degree ); superior high-temperature oxidation and sulfidation resistance.

 

3. Typical Applications

	1.4301	Cost-effective, meets food-grade standards (e.g., FDA).
	1.4401	Excellent seawater resistance, prevents chloride-induced pitting.
	1.4401	Resistant to acids/alkalis, especially Cl⁻-containing media.
	1.4301
High-temperature components	1.4401

4. Key Performance Data

	1.4301	1.4401
Salt Spray Test (ASTM B117)	500–1000 hours (white rust)	2000–3000 hours (no visible rust)
Pitting Potential (ASTM G61)	~+200 mV (vs SCE)	~+500 mV (vs SCE)
		Reduced risk with low-carbon variant (1.4404)
Sulfuric Acid Resistance (5% H₂SO₄, 25 degree )	Corrosion rate: 0.1 mm/year	Corrosion rate: 0.01 mm/year