Failure Intelligent Data Analysis Research of Last Stage Blades of Feedwater Pump Turbine in a Power Plant

1Cr12Ni3Mo2VN stainless steel, due to its higher strength performance, plastic toughness properties and cost advantages, is widely used as the final blade material for steam turbines. Because of the low operating temperature of the final stage blades, the blades are inclined to break due to pitting corrosion, stress corrosion and corrosion fatigue when the steam quality is poor. In this paper, through chemical composition analysis, mechanical performance test, metallographic inspection, and macroscopic and microscopic inspection and analysis of the cracked blades which are worked in a power plant's feed water pump steam turbine. The research shows that there is pitting corrosion on the cracked blades which is the source of the fatigue. Under the combined action of alternating stress, the propagation of cracks is accelerated, and ultimately leads to blade cracks. And based on this failure analysis, relevant quality improvement suggestions are put forward to the power plant.