Investigating the reliability of ultrasound phased array method and conventional ultrasonic testing for detection of defects in austenitic stainless steels

Download

index.pdf

Date

2015

Author

Akgün, Bahadır

Metadata

Show full item record

Item Usage Stats

297
views

126
downloads

In recent years Phased Array (PA) method has become an alternative to the conventional ultrasonic method for critical tests in aerospace, oil, gas and nuclear industries. There is a challenge for inspection of austenitic stainless steels due to high attenuation, skewing and scattering of sound beam. The aim of this thesis is to investigate and to compare the flaw detection abilities of conventional ultrasonic and PA systems using the probability of detection (PoD) approach for testing of austenitic stainless steel blocks and weldments having both artificial and natural defects. Grain size, micro hardness, attenuation measurements, radioscopic and macroscopic inspections were also performed. Three types of test blocks were prepared from AISI 304 steel. First specimen is the block having ø2 mm side drilled holes at different depths; second specimen has side drilled holes with varying diameters between 0.5 to 5 mm at the same depth; and the third specimen is the welded plate having both artificial and natural defects. Although PA method has automated calibration, beam focusing and steering abilities, the PoD analyses did not show remarkable advantage of PA for detecting artificial flaws, except those in the surface near zone. On the welded specimen, however, the PA inspection is clearly more successful than conventional method based on counts of detected flaw possibilities as well as positioning and sizing of the defects. While the automated PA system has superior vi detection and positioning abilities over the manual PA system, the manual PA system has superiority of faster scanning and swiveling of the probe which also brings the risk of human factor.

Subject Keywords

Stainless steel., Phased array., Ultrasonic testing., Metals, Austenitic stainless steel.

URI

http://etd.lib.metu.edu.tr/upload/12619030/index.pdf
https://hdl.handle.net/11511/24982

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Investigating the effect of biofouling on propeller characteristics using CFD Owen, David; Demirel, Yigit Kemal; Oğuz, Elif; Tezdogan, Tahsin; Incecik, Atilla (2018-07-01) Increasing pressure is being placed on the marine industry to address ship emissions, regulations to govern the efficient operation of ships in the form of the Energy Efficiency Design Index (EEDI) and Energy Efficiency Operation Index (EEOI) have recently come into force. All aspects of ship design and operation that impact the energy efficiency of ships are subject to revaluation. This paper investigates the detrimental effects of biofouling on the performance of Potsdam Propeller Test Case (PPTC) propell...
An investigation of two-phase slug flow in inclined pipelines Bağcı, Ali Suat (Informa UK Limited, 2004-06-01) Two-phase slug flow in inclined pipelines can cause significant practical operating problems. When slugs flow in an inclined pipeline that contains sections of different inclinations, they undergo a change of length and slug flow characteristics as the slug moves from section to section. In addition, slugs can be generated at low elbows, dissipate at top elbows and shrink or grow in length as they travel along the pipe. A mathematical model and a computer program were developed to simulate these phenomena. ...
An experimental study on the hypergolic ignition of hydrogen peroxide and ethanolamine Ak, M. A.; Ulaş, Abdullah; Sumer, B.; Yazici, B.; Yildirim, C.; Gonc, L. O.; Orhan, F. E. (Elsevier BV, 2011-01-01) This paper presents the hypergolic ignition test results of a potential environmentally friendly liquid propellant consisting of hydrogen peroxide oxidizer (with a concentration of 85%) and ethanolamine fuel for use in rocket engines. Open cup drop tests were conducted to study the effect of amount of metal salt catalyst in fuel and the initial temperatures of fuel and oxidizer on the ignition delay time. To test the hypergolic ignition of bipropellant formulation in a real rocket engine environment, a pres...
On the estimation of kinetic parameters of organic matters using linearization methods Uraz, Irtek; Akın, Serhat; Kök, Mustafa Verşan (Elsevier BV, 2004-08-01) Kinetic parameters obtained by various thermal analysis methods are widely used in petroleum and other industries. These methods are restricted to relatively simple models that consist of a single equation and have usually uneven sensitivity on the uncertainty of the experimental data due to logarithmic conversions. An important consideration affecting the success of the linearization methods is that the proper selection of the beginning and the end of the linear section. A new method was implemented in adv...
Investigation on effect of equivalence ratio and engine speed on homogeneous charge compression ignition combustion using chemistry based CFD code Ghafouri, Jafar; Shafee, Sina; Maghbouli, Amin (National Library of Serbia, 2014) <jats:p>Combustion in a large-bore natural gas fuelled diesel engine operating under Homogeneous Charge Compression Ignition mode at various operating conditions is investigated in the present paper. Computational Fluid Dynamics model with integrated chemistry solver is utilized and methane is used as surrogate of natural gas fuel. Detailed chemical kinetics mechanism is used for simulation of methane combustion. The model results are validated using experimental data by Aceves, et a...

Citation Formats

B. Akgün, “Investigating the reliability of ultrasound phased array method and conventional ultrasonic testing for detection of defects in austenitic stainless steels,” M.S. - Master of Science, Middle East Technical University, 2015.