Because grade 304 steel has a low carbon content, its corrosion resistance is similar to that of 304 steel under normal conditions, but after welding or stress relieving, its intergranular corrosion resistance is excellent; even without heat treatment, it can maintain good corrosion resistance, and the working temperature is -196 ℃ to 800 ℃. It is used in outdoor machines in chemical, coal and oil industries that require high intergranular corrosion resistance, heat-resistant parts of building materials, and parts that are difficult to heat treat.