304 Stainless Steel Basics: Properties, Applications & FAQs

Q1: What is 304 stainless steel and why is it so widely used?

A1: 304 stainless steel is an austenitic stainless steel alloy containing 18-20% chromium and 8-12% nickel. Its wide application is attributed to its excellent corrosion resistance, good ductility, weldability, and relatively cost-effective performance. It can withstand most atmospheric environments and mild chemical corrosions, making it suitable for diverse industrial and daily use scenarios.

Q2: What is the difference between 304 and 304L stainless steel?

A2: The main difference lies in carbon content: 304 stainless steel has a maximum carbon content of 0.08%, while 304L (L stands for low carbon) has a maximum carbon content of 0.03%. 304L offers better intergranular corrosion resistance after welding, making it ideal for welded structures that require corrosion resistance in high-temperature environments. However, 304 has slightly higher strength than 304L.

Q3: Is 304 stainless steel magnetic?

A3: Normally, 304 stainless steel is non-magnetic or weakly magnetic. This is because it has a stable austenitic structure at room temperature. However, weak magnetism may occur after cold working (such as stamping, bending) due to the transformation of part of the austenitic structure into martensite. This weak magnetism can be eliminated by annealing heat treatment.

Q4: What is the operating temperature range of 304 stainless steel?

A4: 304 stainless steel can operate stably in a temperature range of -270°C to 870°C. At low temperatures, it maintains good toughness without brittle fracture; at high temperatures, it retains certain strength and oxidation resistance. However, when used continuously above 870°C, its chromium content may decrease, affecting corrosion resistance, so it is not recommended for long-term use in environments exceeding this temperature.

Q5: What are the common surface finishes of 304 stainless steel?

A5: Common surface finishes include 2B (cold-rolled, matte finish, widely used in equipment and decoration), BA (bright annealed finish, with a mirror-like appearance, suitable for decorative parts and food machinery), No. 4 (brushed finish, with uniform lines, used in architectural decoration and kitchenware), and HL (hairline finish, with fine linear textures, popular in high-end decoration).