Acetic acid is an important raw material for organic synthesis and is widely used in chemical, light industry, medicine, and food industries. In an acetic acid environment, it is easier for stainless steel to resist corrosion. For example, in pure acetic acid, ordinary Cr17 ferritic stainless steel can withstand dilute acetic acid with a temperature below 80°C and concentrated acetic acid with a concentration greater than 70%; ordinary 18-8 chromium-nickel austenitic stainless steel can withstand low temperatures. Below 50℃, acetic acid with a concentration of 99% and acetic acid vapor with a concentration of 100%.

As the content of molybdenum in stainless steel increases, the resistance to acetic acid corrosion of Cr17 ferritic stainless steel and chromium-nickel austenitic stainless steel will also increase. For example, stainless steel containing 2% molybdenum Cr18Mo2 and Cr17Ni12Mo2 can withstand normal pressure. Acetic acid at any concentration below boiling temperature.

When chloride ions are present in acetic acid, the corrosion rate of stainless steel will be significantly increased. For example, when concentrated acetic acid contains about 1% NaCl, the corrosion rate of ordinary chromium-nickel austenitic stainless steel will increase about 50 times; when the concentration reaches 99%, the chloride ion content in acetic acid increases from 0.0002% to 0.002%. , the corrosion rate will increase significantly. Therefore, in order to solve the corrosion problem of acetic acid containing chloride ions, depending on the concentration of chloride ions in acetic acid, Cr17Ni12Mo2 containing 2%-3% molybdenum and Cr19Ni13Mo3 containing 3%-4% molybdenum can be used with high-molybdenum stainless steel, such as 00Cr18Ni16Mo5, 00Cr20Ni25Mo4 .5Cu and duplex stainless steel 00Cr25Ni7Mo3N, etc.

When the acetic acid solution contains formic acid, the corrosiveness of the solution will become greater as the concentration of formic acid increases. Tests in 50% acetic acid show that as the formic acid content increases, the corrosion rate of stainless steel and some corrosion-resistant alloys increases. However, duplex stainless steel 00Cr25Ni7Mo3N and nickel-based corrosion-resistant alloy 00Cr16Ni60Mo16W4 among stainless steels are basically not affected by corrosion, so they are ideal corrosion-resistant materials.

Formic acid is a widely used organic acid, and the choice of formic acid-resistant stainless steel is different from that of acetic acid-resistant stainless steel. Because formic acid is more corrosive than acetic acid, the alloying degree of the selected stainless steel grade is higher than that of acetic acid. In some cases, a nickel-based corrosion-resistant alloy must be selected. However, when formic acid contains chloride ions, the corrosion rate of stainless steel will be significantly increased.