3898

3681

كارشناسي ارشد

انتخاب و روش ساخت

اصفهان: دانشگاه صنعتي اصفهان، دانشكده مهندسي مواد

1386

نه، 100، [II] ص.: مصور، حدول، عكس ﴿رنگي﴾، نمودار

ص. ع. به فارسي و انگليسي

احمد كرمانپور

سعيد ضيايي راد، حسن فرهنگي

8/2/87

عباس نجفي زاده، محمدرضا فروزان

1396/03/06

كتابنامه

مواد

مهندسي مواد

ID3681

به فارسي و انگليسي: قابل رويت در نسخه ديجيتال

AbstractThe present project focuses on the failure analysis of high pressure gas turbine compressorblades in Hesa power plant Five cases of premature failures happened inth high pressure sectionof the compressor in Hesa power plant three of which happened in the 9 one in the 10th andone in the 12th stage of compressor Since the latest failures happened in the 9th row and moreinformation was available about them the project focuses on the 9th stage of compressor withTi 6Al 4V blades Fracture surfaces cracked blade different parts of the blade alloy and alsothe disk alloy were metallurgically investigated Chemical analysis tensile test hardness test optical and electron microscopy and fractography analysis were performed on the samples Also considering the steady working condition of the compressor the stresses due tocentrifugal forces in the dovetail of the blade and the disk were analyzed using numericalfinite element method and the stress distribution was studied Fretting fatigue seems to be the dominant mechanism in the failure of the compressor blades This mechanism is dominant when the two surfaces have very limited less than 50 micron relative movement and undergo alternating loads In order to become more familiar with thismechanism its different characteristics specifically fretting fatigue of Ti alloys have beenexplained in the second chapter of this report It seems that one of the main effective factors on the increasing the sever localized stress inthe dovetail of blade and sever wear in this region is unsuitable overhaul of compressor andthe lack of enough gap and distance in dovetail of the blade and disk leading the root of bladeto undergo more stresses during the service In addition the soft coating increases frictioncoefficient which leads to severe wear in the blade root and disk This situation has led thefretting fatigue mechanism to be activated rapidly in this blade According to the studies performed by different turbine producing companies such as Pratt Whitney in Canada in addition to the need to control the installation of the blades on the disk and also providing required equipments to carefully control the compressor s bleeding valves two suggestions have been offered to increase the resistance of Ti blades to fretting fatigue which are as follows Using suitable surfacing process and coating on the blades such as sandblasting and using DLC or plasma nitration coatings application of compression stresses such as Low plasticity burnishing LPB or both

احمد كرمانپور

سعيد ضيايي راد، حسن فرهنگي

عباس نجفي زاده، محمدرضا فروزان