Question5.19. Compactly bandy swab spray test for erosion test. Answer The swab spray is a popular erosion test system used to test the erosion resistance of accoutrements and coatings. Generally, test accoutrements are metallic and finished with a coating designed to give some degree of erosion protection to the base essence. This is an accelerated erosion test that exposes a sample carpeted with to erosion action to estimate the felicity of the coating for use as a defensive finish with The appearance of erosion products is estimated after a destined time. The duration of the test depends on the erosion resistance of the coating, in general, the further erosion resistant the coating, the longer the test time before erosion appears. The swab spray test is popular because it’s fairly cheap, presto, well standardized and fairly reproducible. The swab spray test is generally used for phosphated shells, zinc and zinc amalgamation coatings, chrome, nickel and organic coatings. That5.20. Compactly describe the stress test. Answer The machine generally used in this test is the Universal Testing Machine( UTM). In this test, a tensile cargo P is gradationally applied to the test instance For each value of the cargo, the extension in the hand length is L. Changing the length beyond the yield point can be done using a perfection scale. The sample eventually breaks due to sound. A stress- strain wind is also drawn to help calculate the reduction incross-sectional area Ar and chance extension Que5.21. Compactly explain flexural testing. Answer The bending test can be performed on a tensile test bench using some accessories The bending test is a simple and affordable test. The system is fast and shows utmost welding blights relatively directly. wind tests can be used to find some welding parcels similar as weld zone continuity, ii. Making a weld, iii. Fusion, iv. Crystal structure and times of strength. The bend test helps determine the strength of the weld essence, the weld joint and the heat affected zone. The test shows the quality of the weld. Any cracking of the essence is a sign of indecorous melting or imperfect penetration. Large chargers generally indicate incorrect welding system or poor heat treatment after welding. A good weld has small chargers. Fleb tests can be classified as follows free flexion test and ii. Controlled bending test. That5.22. What do you understand by surveying electron microscope( SEM)? Answer A scanning electron microscope is a type of electron microscope that produces images of a sample by surveying a face with a focused electron ray. Electrons interact with tittles in the sample, producing colorful signals that contain information about the face geomorphology and sample composition. The electron ray is scrutinized in raster scanning, and the position of the ray is combined with the detected signal intensity to produce an image In the SEM, secondary electrons emitted by tittles excited by the electron ray are detected using secondary electron sensor. The number of detected secondary electrons and therefore the signal intensity depends one.g. sample geomorphology. That5.23. Write a short note on EDS. Answer Energy dispersiveX-ray spectroscopy( EDS) is a chemical microanalysis fashion used in confluence with a scanning electron microscope( SEM). It detectsX-rays emitted by the sample during electron ray hail to dissect the essential composition of the anatomized volume. The EDSX-ray sensor measures the relative cornucopia of emitted X-rays in relation to their energy. The sensor is generally a lithium drift silicon solid state device. When the incomingx-ray ray hits the sensor, it produces a charge palpitation commensurable to the energy of thex-ray ray. The charge palpitation is converted into a voltage palpitation using a charge-sensitive preamplifier. The signal is also transferred to amulti-channel analyzer where the beats are sorted by voltage. The energy determined by measuring the voltage of each incomingX-ray image is transferred to a computer for display and farther data evaluation. That5.2 Compactly explainX-ray with neat sketch. Answer X-rays are produced in anX-ray tube(Fig.5.2 1), where the hair of the cathode produces electrons that move towards the target anode, megahit and suddenly stop, some of their kinetics. energy is converted into radiation orx-ray energy. The part of the weld with suspected blights is exposed tox-ray radiation from thex-ray tube Figure 1).5.2 1). The cartridge containing theX-ray film is placed vertical to the shafts before and in contact with the weld. During exposure, theX-rays access the welding object and therefore affect the X-ray film. Since utmost blights( similar as blow holes, porosity, cracks,etc.) are lower than the sound base essence, they transmitX-rays better than the sound essence, so the film appears darker on the blights. agree with anx-ray. X-ray film exposed and developed, showing light and dark areas, is called anX-ray image. That5.26. Write a short note on Welding Method Specification WPS). Answer A welding procedure specification( WPS) is a written procedure developed to give instructions for making product welds in agreement with public canons and is intended to determine whether a weld designed for construction can give the needed. parcels for its intended operation. The welder must be an educated worker and mustn’t compromise on the choice of The WPS includes both significant and minor variables in respectable areas. That5.27. Explain the validity of the welding system specification. Answer The appearance of welding process specification( WPS), welding process qualification record( PQR), welding performance qualification and welding accessory qualification is veritably important to insure the required quality of welding. It can not be compromised because the consequences can be disastrous. The Welding Procedure Qualification Record( PQR) is the welding data record used to weld the test pasteboard and contains the variables recorded during welding and the results of the colorful tests performed. Welder Job Qualification ensures that good welders using approved welding styles can produce the minimal conditions for an respectable weld. Welding machines are tested under the full supervision and control of the manufacturer. Qualification of a welder is limited by applicable variables given for each welding process for each weld type and station Performance tests are designed to determine the capability of welders to make sound welds. Eligibility
