Open AccessFailure Analysis in Lacing Wire Of Last Stage Low Pressure Steam Turbine Blade
Author(s) -
A M Kongkong,
Hery Setiawan,
J Miftahul,
A R Laksana,
Imam Djunaedi,
Suwarno Suwarno
Publication year - 2021
Publication title -
iop conference series. materials science and engineering
Language(s) - English
Resource type - Journals
eISSN - 1757-899X
pISSN - 1757-8981
DOI - 10.1088/1757-899x/1096/1/012097
Subject(s) - welding , fractography , materials science , fatigue testing , structural engineering , fracture (geology) , stub (electronics) , finite element method , failure causes , composite material , engineering , reliability engineering
The present paper studies a root cause of failure analysis of lacing wire used in the last stage blade of low pressure (LP) steam turbine. The lacing wire is made of Stainless Steel Grade 17-4 PH with a diameter of 1.4 mm. The failure occurred after the unit had been operated for 4 years. The fault occurred several times during the operation periods. The failure location is near the tack weld which has functions as a stopper between the lacing wire and the stub. Macro fractography, light optical microscope and scanning electron microscope were used to examine the fracture surface and microstructure closed to the failures. The cyclic stress was evaluate using harmonic analysis simulation using FEA (finite element analysis) Ansys 2019 R2. The benchmark that is indication of fatigue failure was clearly visible. It is concluded that the failure mechanism is fatigue failure with crack initiation. Improper maintenance procedures especially welding procedures trigger an initial crack and then the initial crack gets a concentrated cyclic load causing lacing wire broken.