Cause Analysis of Rusting of 1Cr15Ni27Mo1Ti3Al Stainless Steel Spring

Springs made of ϕ0.8 mm 1Cr15Ni27Mo1Ti3Al stainless-steel showed slight brown-red rust after functional test along with the products. After salt spray testing, the surface of the springs showed severe brown-red rust. Scanning electron microscopy and metallographic microscopy were used to observe micro surface appearance of the springs. The chemical composition of the spring rust was tested by energy spectrum. The results show that the spring rust only occurred at the oxide film, and the spring substrate had no corrosion. The oxide film on the spring surface mainly formed in the aging process. There were many gaps in the oxide film of springs because of the poor quality of the spring surface and the cracking in oxide film formed in high-temperature aging process. The gaps absorbed the environmental media in the humid environment, resulting in chemical reaction and then generating brown-red rust. The methods of pickling, sand blasting and grinding can not completely remove the oxide film of spring formed in aging process, and electrolytic polishing can regenerate a very thin and dense oxide film layer on the spring surface to obtain satisfactory corrosion resistance. Improving the surface quality of the spring wire and using the low temperature aging in vacuum furnaces can also obtain a satisfactory corrosion resistance.