Effect of Boron Added Corrosion Behavior of Cast 304 Stainless Steel

Seven groups of the cast 304 stainless steels with boron addition as 0, 10, 20, 30, 40, 50, and 60 ppm were used to investigate their corrosion behavior by electrochemical potentiodynamic polarisation capacities in 10% HNO3 solutions at laboratory environment. The effect of solution heat treatment at 800 degrees C, 900 degrees C and 1000 degrees C for 1h on corrosive resistance of cast 304 stainless steel was also investigated. Microstructures and corrosion morphologies were examined by optical microscopy, X-ray diffraction analyses and scanning electron microscopy. Because of experiments, improvement of corrosion resistances depending on the amount of added B and heat treatment conditions were observed. Adding B to the cast 304 stainless steels improved its resistance to corrosion, but its resistance to intergranular corrosion reduced, which can be seen by the corrosion morphology. The improved corrosion resistance of cast 304 stainless steel was attributed not only to the added boron, but also solution-annealing treatment compared with non-borided cast 304 stainless steel.