Environmental protection industry: Industrial waste gas, garbage and sewage treatment plants need to be made of stainless steel. In the process of flue gas desulfurization, in order to withstand the corrosion of sulfur dioxide, chloride ions and iron ions, duplex stainless steels and high-grade austenitic stainless steels are required at absorption towers, coolers, pumps, valves, and flue gas ducts. Waste incinerators, waste water treatment and other facilities need to be made of high-performance stainless steel materials.