What's the Difference Between 304 and 304L ?

Sakysteel Type 304 is a variation of the basic 18-8 grade, Type 302, with a higher chromium and lower carbon content.Lower carbon minimizes chromium carbide precipitation due to welding and its susceptibility to intergranular corrosion.In many instances, it can be used in the ”as-welded“ condition, while Type 302 must be annealed in order to retain adequate corrosion resistance.Type 304L is an extra low-carbon variation of Type 304 with a 0.03% maximum carbon content that eliminates carbideprecipitation due to welding.

As a result, this alloy can be used in the ”as-welded“ condition, even in severe corrosive conditions. It often eliminates the necessity of annealing weldments except forapplications specifying stress relief. It has slightly lower mechanical properties than Type 304.

Type 304 and 304L Stainless Steel Composition:

304 Stainless Physical Properties:

• Density: 0.803g/cm³
• Electrical resistivity: 72 microhm-cm (20C)
• Specific Heat: 0.50 kJ/kg-K (0-100°C)
• Thermal conductivity: 16.2 W/m-k (100°C)
• Modulus of Elasticity (MPa): 193 x 10³ in tension
• Melting Range: 2550-2650°F (1399-1454°C)

HEAT TREATMENTS

Type 304 is non-hardenable by heat treatment. Annealing: Heat to 1900 - 2050°F (1038 - 1121°C), then cool rapidly. Thin strip sections may be air cooled, but heavy sections should be water

quenched to minimize exposure in the carbide precipitation region.Stress Relief Annealing: Cold workedparts should be stress relieved at 750°F (399°C) for 1/2 to 2 hours.

Properties and Application

These alloys contain chromium and nickel, as well as carbon, to provide good forming and welding properties, corrosion and oxidation resistance, toughness in low temperatures, ease of fabrication, and attractive appearance.

These 304 and 304L stainless steel products are used for tanks, tools, food industry machinery and appliances, architectural trim, filtration screens, and fasteners in corrosive marine environments.

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