Comparison Of 304 And 304L Stainless Steel: Standard Vs Low-Carbon Austenitic Grade

304 and 304L are typical austenitic stainless steels, with the core difference being carbon content. 304L is the low-carbon variant of 304, which improves intergranular corrosion resistance by reducing carbon content, while 304 has better high-temperature strength. The two are widely used in general corrosion-resistant scenarios, with clear division in welding-intensive and high-temperature applications.

Core Parameter Comparison

Parameter	304 Stainless Steel	304L Stainless Steel
Chemical Composition (wt%)	C≤0.08, Cr=18.00-20.00, Ni=8.00-10.50, Fe=Balance	C≤0.03, Cr=18.00-20.00, Ni=8.00-12.00, Fe=Balance
Mechanical Properties (Annealed)	Tensile Strength ≥515MPa, Yield Strength ≥205MPa, Elongation ≥40%, Hardness ≤201HB	Tensile Strength ≥485MPa, Yield Strength ≥170MPa, Elongation ≥40%, Hardness ≤201HB
Service Temperature	-270℃ to 870℃ (continuous service)	-270℃ to 870℃ (continuous service)
Equivalent Grades	SUS304 (JIS), EN 1.4301, UNS S30400	SUS304L (JIS), EN 1.4306, UNS S30403

Key Performance Differences: 1. Intergranular corrosion resistance: 304L avoids chromium carbide precipitation at grain boundaries due to low carbon content, with excellent intergranular corrosion resistance without post-weld heat treatment; 304 is prone to intergranular corrosion after welding or long-term stay in 450-850℃. 2. High-temperature strength: 304 has higher creep strength than 304L at 600-870℃, with creep rate 1/2 of 304L. 3. Weldability: 304L has better weldability, no cold cracking risk, and wider application in welding-intensive components.

Applicable Scenario Distinction: 304 is suitable for non-welding or less welding components, such as household appliances, architectural decoration, food processing equipment (non-welding parts), and high-temperature pipelines (≤870℃). 304L is suitable for welding-intensive components, such as chemical reaction kettles, pressure vessels, marine pipelines, and components requiring post-weld corrosion resistance.

Practical Q&A

Q1: When to choose 304 instead of 304L? A1: Choose 304 if the component has few welds, works at 600-870℃ for a long time, or requires higher strength; 304 has lower cost and better high-temperature performance than 304L.

Q2: Does 304L need post-weld heat treatment? A2: No. Its low carbon content (≤0.03%) avoids chromium carbide precipitation during welding, so post-weld heat treatment is not required to restore corrosion resistance, which simplifies the manufacturing process.

Q3: What is the cost difference between 304 and 304L? A3: 304L is 5-8% more expensive than 304, mainly due to the stricter carbon content control in smelting and the slightly higher nickel content (8-12% vs 8-10.5% of 304).

 

Q4: Can 304L be used in low-temperature environments? A4: Yes. It has excellent low-temperature toughness, with impact toughness ≥100J at -196℃, suitable for low-temperature storage tanks (liquid nitrogen, liquid oxygen) and low-temperature pipelines.

Q5: How to distinguish 304 and 304L by simple methods? A5: The most accurate method is chemical composition analysis (carbon content ≤0.03% for 304L, ≤0.08% for 304); in terms of welding performance, 304L has fewer weld pores and better weld forming under the same process.