REPUBLIC OF SERBIA

MINISTRY OF DEFENCE

www.mod.gov.rs

MINISTRY OF DEFENCE

Material Resources Sector

Defensive Technologies Department

Military Technical Institute

www.vti.mod.gov.rs

Failure analysis of the Stator blade

Jelena Marinković

Military Technical Institute, Belgrade, jecamarinkovic@gmail.com

DuŠan VraČariĆ

Military Technical Institute, Belgrade, vracaricd@gmail.com

Ljubica Radović

Military Technical Institute, Belgrade, ljubica.radovic@vti.vs.rs

Ivo Blačić

Military Technical Institute, Belgrade

Abstract: Materials used to make  rotor and stator turbine blades are designed to be very durable and have a lifespan from 25 till 40 years in very difficult conditions of working environment. However, the lifetime of blades and proper functionality dramatically reduces the presence of abrasive reagents within the exploatation  environment. Therefore, the special types of stainless steel (with chromium content 11 ÷ 12 wt.% and low nickel content 0.3 ÷ 0.8 wt.%) are used to make the blades. This paper presents an failure analysis of the stator blade made of special martensitic creep-resisting steel (grade X22CrMoV12-1). The investigation of the fracture was conducted at the blade root by the  macro fractographic analysis on the stereo microscope and microfractographic analysis of the fracture surface on the scanning electron microscope (SEM). Fractographic analysis showed that the fracture has occurred due to the presence of corrosion pits and that cracks were propagated by the mechanism of corrosion fatigue.

Keywords: stator blade, failure, pitting corrosion, fractographic analysis.