Fatigue behaviour of nitrided low alloy steel in 3NaCl solution

摘要

This paper describes the corrosion fatigue behaviour of nitrided low alloy steel (Cr-Mo steel). Rotary bending fatigue tests have been performed in 3%NaCl solution using specimens with different nitride case depths. The corrosion fatigue strengths of the nitrided materials increased compared with the untreated material and with increasing the thickness of the compound layer. All the materials showed lower fatigue strength in 3%NaCl solution than in laboratory air. Corrosion pits were seen underneath the compound layer, from which the crack was initiated. Based on additional fatigue test results, the compound layer was found to play a significant role in improving corrosion fatigue strength. Because of the porous nature of the compound layer, the solution penetrated through the compound layer and reached the base steel.