Liquid penetrate test
- Test on test pieces Damaged after test.
- Determine mechanical properties of test piece under test.
- Tensile test
- Impact Test
- Fatigue Test
- Bend test
- Hardness Test
- Creep Test
- Test on components. Not damaged after test
- Determine flaws or imperfection during manufacture (or) service.
- Liquid penetrating
- Electrical test method
- Ultrasonic method
- Radiographic inspection
- Magnetic crack detection
- Tensile test is used to determine the behaviour of a material up to its breaking point.
- A special shape specimen of standard size is gripped in the jaws of a testing machine. A load is gradually applied to draw the ends of the specimen apart such that it is subject to tensile stress up to yield point.
- The highest value of stress is known as the ultimate tensile stress (UTS) of the material.
- Specimen is bent through an angle of 180 with internal radius of 1.5 times the thickness of the specimen without cracking at edges.
- Testing machine basically consists of a pendulum which is raised and allowed to fall, striking and rupturing the specimen.
- In swinging through its arc of travel past specimen, pendulum assume a lower position at end of its travel due to loss of energy when it strikes the specimen.
- Energy given up to the specimen is its impact strength.
- Hardness test consist hardened steel ball impressing into metal at given pressure for predetermine time.
- Load is 3000 kg for steel and 500 kg for soft metals such as brasses and bronzes.
- Diameter impression indicates the hardness number.
- 'Fatigue' is defined as the failure of a material due to repeatedly applied stress.
- The specimen is rotated under load in a testing machine. So it is subject to tension and compression stresses alternately.
- The number of cycles imposed before is recorded.
- Creep test use to find safe working stress for material working at high temperature
- It is permanent deformation resulting from loading over long period of time
- Test piece mount vertically and constant tensile load under constant temperature.
- Temperature range between 600’C to 1000’C and test period is 1000,10000,100000 hours
Liquid penetrate test
- Industrial method, indicate presence crack, lamination lap and surface porosity.
- Fluorescent dye method and Aerosol dye method.
Fluorescent dye method
- First, the surface is cleaned using a volatile cleaner and degreaser.
- Then a fluorescent dye is applied and a certain time allowed for it to enter any flaws under capillary action.
- Then the surface is wiped clean using the cleaning spray.
- An ultra violet light is shone on the surface, any flaws showing up as the dye fluorescent.
Aerosol dye method
- The more commonly used dye penetrant method is similar in application.
- The surface is cleaned and the low viscosity penetrant is sprayed on.
- After a set time, the surface is cleaned again.
- Then a developer is used which coats the surface in a fine white chalky dust.
- The dye seeps out and stains the developer typically a red colour.
- Probe of test equipment transmits high frequency sound waves about 0.5 MHz to 20 MHz which reflected by any flaws in object
- Reflected sound waves displayed on monitor screen of cathode ray oscilloscope.
- Suitable for detection, identification and size assessment of a wide variety of both surface and sub-surface defects in materials.
- Measured thickness of material or to detect internal or surface defects in welds, casting or forging either during manufacture or when in service.
- Image produced on film.
- X rays and gamma rays are used for inspection of welds, castings, forging and pressure vessels etc.
- Exposure time for x-rays and gamma rays vary with type of material, thickness and the intensity of rays.
- Faults in the metal effect the intensity of rays which passes through the material
- Film exposed by the rays gives the shadow photograph
- Used on both metallic and nonmetallic material, both ferrous and non-ferrous metal