Damage causes and failure analysis of a steam turbine blade made of martensitic stainless steel after 72000 hours of working

Metal magnetic memory (MMM) method, based on the magneto-elasticity and mechanical effect theory, is a new nondestructive testing technology. This paper aims at the material property and failure analysis for steam turbine blade with MMM method. The failure blade and its fracture face are tested with MMM technology at workshop. It has been found that the MMM signal variation gradient of the crack transition zone in the fracture face is minimal, that of the crack initiation zone is in the middle, and that of the tear fracture zone is maximal. MMM testing results reflect material behavior degradation of the failure blade. In order to proof the MMM results, the dynamic stress of the steam turbine blade under the operation loading is calculated by WESTHOMES software and analyzed theoretically. It has proved the validity of the MMM method applied on material property evaluation and failure analysis for steam turbine blade.

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Steam turbine blade failure analysis

Engineering Failure Analysis ◽

10.1016/j.engfailanal.2006.11.018 ◽

2008 ◽

Vol 15 (1-2) ◽

pp. 129-141 ◽

Cited By ~ 44

Author(s):

Zdzislaw Mazur ◽

Rafael Garcia-Illescas ◽

Jorge Aguirre-Romano ◽

Norberto Perez-Rodriguez

Keyword(s):

Failure Analysis ◽

Steam Turbine ◽

Turbine Blade ◽

Steam Turbine Blade ◽

Blade Failure ◽

Turbine Blade Failure

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Study on High Speed Milling of Steam Turbine Blade Materials

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1136.251 ◽

2016 ◽

Vol 1136 ◽

pp. 251-256

Author(s):

Tomonori Kimura ◽

Takekazu Sawa ◽

Tatsuyuki Kamijyo

Keyword(s):

Stainless Steel ◽

Titanium Alloy ◽

Steam Turbine ◽

Turbine Blade ◽

Tool Life ◽

High Speed ◽

Cutting Speed ◽

High Speed Milling ◽

Steam Turbine Blade ◽

Cutting Point

A titanium alloy and stainless steel is an excellent material having properties such as high intensity and high corrosion resistance. Therefore, a titanium alloy and a stainless steel are used as material of steam turbine blade. However, the machining efficiency of a titanium alloy and a stainless steel is a low because of difficult-to-cut materials. Especially, it is a major problem that the cutting point temperature is high and the tool life is short. In the conventional study, it is reported that the cutting point temperature is low and the tool life becomes long by cutting at the suitable cutting speed corresponding to material characteristics. This concept is known as high speed milling. In recent years, the high speed milling is actually used for the metal mold machining. In this study, the high speed milling of the titanium alloy and the stainless steel was tried for the purpose of high efficiency cutting of a steam turbine blade. In the experiment, the cutting tool used the TiAlN coating radius solid end mill made of micro grain cemented carbide. The diameter of endmill is 5mm. The corner radius is 0.2mm. And, the work piece is the titanium alloy Ti-6Al-4V and stainless steel 13Cr. The cutting speed carried out at 100m/min~600m/min. As the result, when the tool life and the surface roughness was a valuation basis, the optimum cutting speed of titanium alloy was 300m/min. On the other hand, In the case of the stainless steel, the flank wear becomes large in proportion to cutting speed. The feature of high speed milling was not able to be confirmed in the range of this experimental condition.

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