Subject:- Applied Physics(PHY)CHAPTER NO: 02

Non-Destructive Testing of Materials (10 Marks)

BY

Prof. Kokare A.Y.

BABASAHEB PHADTARE POLYTECHNICKALAMB-WALCHANDNAGAR.

B.P.P. Kalamb-Walchandnagar Prof. Kokare A.Y.

Ultrasonic Waves “The sound waves having frequency more than 20 kHz are called as ultrasonic waves”.

Range for Infrasonic, Sonic and Ultrasonic Frequency 1) Infrasonic waves : Less than 20 Hz. 2) Sonic Waves : Between 20 Hz to 20 kHz. 3) Ultrasonic waves : More than 20 kHz.

State the Properties Of Ultrasonic Waves 1) Frequency of ultrasonic waves is more than 20 kHz. 2) Ultrasonic waves has shorter wavelength. 3) Ultrasonic waves travel long distance without considerable loss. 4) Due to passing Ultrasonic waves, temperature of fluid increases. 5) Ultrasonic waves travel with constant speed through homogenous medium. 6) Ultrasonic waves show less diffraction. 7) Ultrasonic waves carry high amount of sound energy. B.P.P. Kalamb-Walchandnagar Prof.

Kokare A.Y.

B.P.P. Kalamb-Walchandnagar Prof. Kokare A.Y.

Piezoelectric Effect in Clock.mp4

Necessity of Testing :- Testing of materials is necessary : 1) To detect defects in material. 2) To determine physical, chemical, mechanical properties of material. 3) To determine breaking stress, hardness, strength of material. 4) To check suitability of material.

Destructive Testing :- “The method of testing of material with destruction of material is called as destructive testing”. In this method, material cannot use after testing and 100% testing is not possible. B.P.P. Kalamb-Walchandnagar Prof. Kokare A.Y.

Non Destructive Testing :- “The method of testing of material without destruction of material is called as non destructive testing”. In this method, material can used after testing and 100% testing is possible.

Advantages of NDT :- 1) Material can used after testing. 2) 100% testing is possible. 3) Used as quality control tool. 4) Used as quality assurance tool. 5) Testing is possible before manufacturing. 6) Testing is possible after manufacturing. 7) Testing is possible while manufacturing. 8) Testing is possible while servicing.

B.P.P. Kalamb-Walchandnagar Prof. Kokare A.Y.

Limitations of NDT1) Required minimum two testing methods for complete examination of material. 2) Required trained/Expert persons for conduction of testing. 3) Equipment cost is high. 4) Quantitative testing is difficult.

Selection Criteria for NDT Method1) Codes and standard requirements. 2) Nature of material. 3) Nature of defects. 4) Manufacturing process of material. 5) Equipment's available for testing. 6) Required cost.

B.P.P. Kalamb-Walchandnagar Prof. Kokare A.Y.

Different NDT methods used in Industry

1)Liquid penetrant testing (LPT).

2) Ultrasonic testing (UT).

3) Magnetic particle testing (MT).

4) Radiographic testing (RT).

5) Eddy current testing (ET).

6) Visual testing (VT).

7) Holographic testing (HT). B.P.P. Kalamb-Walchandnagar Prof. Kokare A.Y.

B.P.P. Kalamb-Walchandnagar Prof. Kokare A.Y.

2) Application of Dye PenetrantAfter cleaning of surface of material a suitable dye penetrant is applied on surface of material. The dye penetrant slips (enter) into cracks of material. Time required to slips into the cracks is called dwell time. It is near about 20-30 minutes.

3) Removal of Excess Penetrant After dwell time excess dye penetrant is removed from surface of material.

B.P.P. Kalamb-Walchandnagar Prof. Kokare A.Y.

4) Application of DeveloperA thin layer of developer is applied on surface of material. Due to reverse capillarity dye penetrant is comes out on surface i.e. developer pulls penetrant on surface.

5) Inspection And EvaluationThe inspection of material is done under white light or UV light depending on penetrant used. White light is used when visible dye penetrant used and UV light is used when fluorescent light used.

6) Post Cleaning Using cleaning reagent material is cleaned and can be used for intended purpose.

B.P.P. Kalamb-Walchandnagar Prof. Kokare A.Y.

Dye Penetrant Inspection.mp4

Advantages of LPT 1) It can be used for all metals and non metals. 2) It can be used for any size and shape of material. 3) It requires less cost. 4) High sensitivity (small discontinuities can be detected).

Limitations of LPT 1) It is used only for surface defects. 2) It is not suitable for porous material. 3) Requires expert person. 4) Surface finish and roughness can affect inspection sensitivity. 5) Pre-cleaning is critical since impurities can cover defects. B.P.P. Kalamb-Walchandnagar Prof.

Kokare A.Y.

Applications Of LPT 1) LPT is used to detect surface open cracks in welds (e.g. pipes, turbine, etc.). 2) It is used to detect surface open cracks in forgings (e.g. crank shaft). 3) It is used to detect surface open cracks in castings (e.g. piston head). 4) It is used to detect surface open cracks in rolled products (e.g. rolling stocks).

B.P.P. Kalamb-Walchandnagar Prof. Kokare A.Y.

Characteristics of Penetrant Selection of penetrant is depends on following characteristics : 1) Penetrant should possess low surface tension. 2) Penetrant should possess low viscosity. 3) It should wet material. 4) It should easily available. 5) It should easily removable. 6) It should have high sensitivity to light. 7) It should be good solvent.

B.P.P. Kalamb-Walchandnagar Prof. Kokare A.Y.

Characteristics of Developer Selection of developer is depends on following characteristics : 1) Developer should possess high absorption ability. 2) Developer should possess low viscosity. 3) It should wet material. 4) It should easily available. 5) It should easily removable. 6) It should have high sensitivity to light. 7) It should be good solvent.

B.P.P. Kalamb-Walchandnagar Prof. Kokare A.Y.

Ultrasonic Testing (UT) There are various UT methods used in industries. 1) Through transmission UT method 2) Pulse Echo UT method 3) Resonance method

Principle The principle of UT method is “When ultrasonic waves are incident on a material, it gets reflected from crack”.

B.P.P. Kalamb-Walchandnagar Prof. Kokare A.Y.

1) Through transmission UT method

B.P.P. Kalamb-Walchandnagar Prof. Kokare A.Y.

Through transmission- Ultrasonic Testig Through transmission.mp4

2) Pulse Echo UT method

B.P.P. Kalamb-Walchandnagar Prof. Kokare A.Y.

Ultrasonic Pulse Velocity-Echo Testing of Concrete, Rock, Wood and Ceramics with Pundit PL-200-PE.mp4

Ultrasonic Testing.mp4

Advantages of UT 1) It detects internal as well as open cracks. 2) It has high sensitivity. 3) It has high reliability. 4) It can be used for all types of materials (metals, alloys, wood, etc.) 5) Atomization is possible. 6) Equipment is portable and easy to handle. 7) This method is harmless. 8) It is highly accurate. 9) Less preparation is required. 10) It can be used to measure thickness of material.

B.P.P. Kalamb-Walchandnagar Prof. Kokare A.Y.

Limitations of UT

1) It requires expert person for operating the device. 2) It requires coolant for effective transfer of ultrasound. 3) Calibration is required before testing. 4) Material of irregular surface is difficult to inspect. 5) The materials of low sound transmission are difficult to inspect. B.P.P. Kalamb-Walchandnagar Prof.

Kokare A.Y.

Applications of UT 1) UT is used to detect flaws (cracks) in all metals, rubber, tyres, concrete, wood, plastic. 2) Rail inspection : UT is used for inspection of rails. 3) Air craft inspection : UT is used to detect cracks in body of air craft. 4) Tunnel inspection : The cracks in wall of tunnel can be detect using UT method. 5) Bridge inspection : The cracks in the pillars and slab of bridge are detect using UT method. 6) It is used to detect subsurface flaws in forging components. 7) It is used to test plant components and systems.

B.P.P. Kalamb-Walchandnagar Prof. Kokare A.Y.

Difference between Destructive testing and Non Destructive testing

B.P.P. Kalamb-Walchandnagar Prof. Kokare A.Y.

Thank youThank you

B.P.P. Kalamb-Walchandnagar Prof. Kokare A.Y.