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Right answer is (b) False

The BEST I can EXPLAIN: In IMPACT testing of materials, the notches in specimen are made intentionally to INCREASE the stress concentration so as to increase the tendency to fracture as most of the mechanical components have stress raisers. The notch material should be tough enough to WITHSTAND the impact force.

The correct ANSWER is (d) ULTRASONIC inspection

Explanation: Ultrasonic inspection is used to detect defects like cracks and porosity within the interior of the casting or material. This method USES reflection and transmission of high frequency SOUND waves, which are much higher than the audible range and then these waves are MADE pass through the casting for inspection.

Right choice is (b) False

Easiest explanation: Sound test is a very rough test to INDICATE any flaws or discontinuities in the casting. The casting is SUSPENDED by suitable support and tapping is done at the surface of the casting with a hammer that makes a variation in the tone which INDICATES the existence of flaws. This method does not indicate the exact LOCATION and EXTENT of the discontinuity in the casting.

Correct ANSWER is (a) True

For explanation I would say: Destructive tests are mainly CARRIED out to the specimen’s failure, in order to evaluate a specimen’s performance or material’s behavior under different loads. These tests are MUCH easier to carry out, GIVE more information, and are easier to interpret than non-destructive tests.

Right answer is (a) True

Explanation: Inspections are mainly CARRIED out before a lot of castings have been COMPLETED to detect any FLAWS that may have occurred in the process so that corrective measures can be taken to remove the defect in the remaining units. MANY ways or METHODS are performed to inspect the castings.

The CORRECT option is (c) Nitride pitting

Explanation: For the formation of negative surface IRREGULARITIES, slag and oxide inclusion, oxidation pitting, GAS and SHRINKAGE are very important factors, but not nitride pitting, as it does not cause negative surface irregularity.

Correct ANSWER is (a) True

Explanation: Magnetic PARTICLE inspection is a highly effective and SENSITIVE technique for revealing cracks or similar defects at or just beneath the surface of castings made of ferromagnetic metals. This method is WIDELY USED where high accuracy and complete defects free castings are required.

Right option is (B) DYE penetrant inspection

The best explanation: Dye penetrant inspection method is mainly used to DETECT invisible surface DEFECTS in a nonmagnetic casting. The casting is cleaned by BRUSHING, and then spraying or dipping of the casting is done into a dye containing a fluorescent material. Then for inspection, casting is dried and viewed in darkness that reveals the discontinuities in the surface.

Correct option is (b) False

Easy explanation: Destructive TYPE of testing suffer from the disadvantage that the saw cuts MAY miss the flaw or the sample may not represent the behavior of the ENTIRE lot, and as the name SHOWS that it damages the product while testing of the castings. So, non-destructive tests are generally more commonly relied UPON than destructive tests.

Correct answer is (b) False

The EXPLANATION is: It is not possible to form a casting of exact required dimensions. The efficiency of exactness cannot be hundred percent, only it can be improved by using better and HIGH quality equipment. Dimensions of each casting will vary SLIGHTLY, so castings are specified by setting a RANGE of values that the dimensions can FALL within.

Right option is (c) Coordinate measuring machine

The explanation is: Coordinate measuring machine (CMM) is basically used for the MEASUREMENT of DIMENSIONS more accurately. HOWEVER, the checking of dimensions of any casting or material can be done MANUALLY but the CMM makes more accurate and precise measurement with HIGH automation.

Right option is (a) True

Easiest explanation: Dimensional inspection is generally carried out to MAKE sure that the CASTINGS produced have the required overall DIMENSIONS including the allowances for the machining process. Sometimes it is necessary to BREAK a part of the casting to take MEASUREMENTS of inside dimensions properly.

The correct option is (a) True

To elaborate: The high-speed cameras used in DESTRUCTIVE testing have advance recording modes to CAPTURE almost any kind of destructive failure. After the failure of casting, CAMERA stops recording and the captured images can be played back in slow motion which SHOWS precise INFORMATION, image by image during and after the destructive test.

The CORRECT option is (c) TROPTOMETER

Easy explanation: A device known as troptometer is basically used to measure angular deformation in torsion TEST. This device mainly consists of two collars which are clamped to the specimen at the DESIRED gauge length, in which one collar is equipped with a POINTER and the other with a graduated scale.

Right choice is (C) Reflectives

To explain I would say: According to the subject CLASSIFICATION of MFFT, the category of reflective has the characteristics of spending LONG time and making LESS errors.

The correct option is (a) True

Easiest explanation: Individual pores do not produce any distinguishable indications under testing conditions. The ultrasonic indication of centre LINE porosity is typically presented or revealed in the form of noise. This makes it very difficult to DISTINGUISH between porosity and large grained structure that GIVES SIMILAR ultrasonic indications.

The correct choice is (b) False

To elaborate: In ultrasonic inspection, ultrasonic BEAM intensity decreases EXPONENTIALLY with the metal travel distance. Ultrasound ATTENUATION in metal influences DISCONTINUITY detection greatly and also the material characterization TECHNIQUE. So, it is very important to establish attenuation measurement practices to carefully perform the inspection.

Correct choice is (a) True

Best explanation: For the USE of penetrant inspection, proper preparation of the test surface is critical because unprepared surface will only reveal gross POROSITY and large cracks on the surface. So for preparing the surface for testing, process like MACHINING, caustic etching, acid PICKLING ETC. are used.

The correct answer is (B) False

To elaborate: Visual inspection can observe most of the surface defects and ROUGHNESS of the castings, but the defects at the interior PART of the surfaces, which cannot be observed easily by naked eyes. So other methods of non-destructive testing are USED where small areas are subjected to sensitive tests to detect surface blemishes.

Right option is (b) False

Easy explanation: Eddy current inspection is generally restricted to the depth less than 6MM, that’s why it is not as sensitive to small open defects of HIGH depth as LIQUID penetrant TESTING (LPT) or MAGNETIC particle inspection (MPI). But it can replace LPT method for detection of surface connected discontinuities.

Right choice is (b) False

Explanation: Penetrant TESTING method is generally USED for detecting very small surface CRACKS and it has an ADVANTAGE over the magnetic particle method that it can be used for any material. A penetrant liquid is used which is drawn into the cracks or voids by means of capillary action. In this method, there is no REQUIREMENT of pressure.

The CORRECT option is (b) False

The explanation is: In charpy TEST, not only the ABSORBED energy, but the percentage of shear fracture area can also be measured. This is generally evaluated by observing the fracture surface of the specimen or work-piece and this estimates the relative AMOUNT of shear fracture, which looks rough or TORN.

Right answer is (C) Visual INSPECTION

To explain I WOULD say: Visual inspection is a type of non -destructive testing technique that provides a means of detecting and examining the variety of surface flaws, such as surface finish, discontinuities and surface cracks on the CASTINGS. This method is very CHEAP and widely used because most of the surface defects and roughness can be observed easily.

Right answer is (B) False

Explanation: DESTRUCTIVE TESTING is the most suitable and economic method for objects which will be mass-produced, it only INVOLVES the cost of DESTROYING a small number of specimens which is quite negligible. Destructive test is not economical where only one or two things are to be produced.

The correct answer is (b) False

For EXPLANATION I would say: It is very important to measure critical dimensions of compact or large castings for dimensional inspection. Measurement of large volume of castings is done for more often to check POSSIBLE drifts, particularly drift is mainly occurs DUE to the wearing of a PATTERN.

The correct answer is (b) False

The best I can explain: In MPI METHOD, the presence of discontinuities and the leakage field is MAINLY DETECTED by the use of finely DIVIDED ferromagnetic PARTICLES applied over the surface, with some of the particles being gathered and held by the leakage field. This magnetically held collection of particles to form an outline of discontinuity, which defines the characteristics of the surface discontinuities.

The correct choice is (B) False

For EXPLANATION I WOULD say: Defective castings can be salvaged, it mainly depends upon the nature and extent of the defect in the castings. Sometimes defective casting is completely REJECTED and re-melted for their material CONTENT, and then this liquid metal is reused for the production of castings.

Correct answer is (a) X- rays

To explain I would say: Radiography uses X-rays, these rays penetrate through the castings and makes a shadow picture on a film which is placed BEHIND the material. These rays have a very SHORT wave length of the order of 0.001 Angstrom. And sometimes gamma rays are ALSO USED for the inspection of castings.

Correct choice is (d) Resilience

To explain I would say: The rebound test of hardness has generally employed some TECHNIQUES to assess the resilience of MATERIAL by measuring changes in potential ENERGY of the material. For EXAMPLE, testing employs a hammer that is dropped onto the SURFACE of the material being tested; same is also used for polymers testing.

The correct option is (a) True

For explanation I WOULD SAY: The tension test is the COMMONLY used test for determining static properties of materials. The data obtained from the test is mainly used to predict failure of parts SUBJECTED to more generalized stress states. Static properties are basically RELATED to the strength and hardness of the material.

Correct option is (a) True

To elaborate: COARSE GRAINED STRUCTURES in thick plates, ingots and cast materials cause considerable increase in attenuation, that shows more loss of energy during an inspection of the castings. It mainly OCCURS due to scattering and diffraction at grain boundaries of the casting material. This is known as ultrasound attenuation.

Correct choice is (c) Fracture toughness

Easy explanation: The fracture toughness parameter is also called as stress intensity FACTOR (K) which is used for heavy sections of high strength and low ductility material of casting developing PLAIN strain conditions, and other energy BASED methods are generally used for COMPARATIVELY thinner sections MADE of low strength and high ductility material.

Correct choice is (a) True

Explanation: The dynamic tear test is used to characterize the fracture properties of ultrahigh-strength steels and also for the aluminum and TITANIUM ALLOYS which generally do not exhibit any SHARP transition temperature behavior. This test is performed by impact loading and results into absorption of energy at VARIOUS testing temperatures.

Correct option is (b) False

The BEST I can explain: VARIOUS equipment are used for mechanical testing which ranges from simple, hand-actuated DEVICES to the complex type of equipment, for example, servo-hydraulic system is one of the complex type which is used in testing and completely controlled through COMPUTER interfaces.

Right option is (a) True

The BEST explanation: In ultrasonic inspection, the instrument is adjusted using a series of REFERENCE standards in the form of cylindrical BLOCKS containing some flat bottom holes of specified sizes at DIFFERENT depths. So the discontinuity size is easily determined by comparing the reflected signal amplitude with that reflected by a flat bottom hole at a SIMILAR depth.

Right ANSWER is (a) True

For explanation: Indentation test ACTUALLY CREATES a permanent IMPRESSION on the surface of material. And the hardness is a function of FORCE and size of the impression, so the force and size of the impression can be related to the hardness which can be objectively related to the resistance of material to the permanent penetration.

Right answer is (c) Ultraviolet light

The explanation is: In LPT METHOD, the OBJECTIVE is accomplished by entrapment of the inspection liquid by the flaws followed by visual inspection of the surface under ultraviolet light (when USING a fluorescent PENETRANT) and for visible dye penetrant, normal light can be used for the inspection process.

The correct OPTION is (b) False

Best explanation: Visual INSPECTION of each casting ensures that none of its features has been omitted or malformed by moulding errors, SHUT running, or mistakes in cleaning. Most of the surface defect can be observed EASILY at this stage, but for sensitive testing, other EXPENSIVE methods of NDT are implemented.

Correct option is (d) Steel ball

Explanation: In this test, a large steel ball of GENERALLY 10 mm diameter is used with a FORCE of relatively large magnitude. This force is usually compatible with either 3000 kg for relatively hard materials such as CAST iron and steel or 500 kg for soft materials such as aluminium and copper ALLOYS. For very hard materials, a tungsten carbide ball is preferred.

The correct answer is (a) True

To ELABORATE: The accuracy of the measuring tools is just as important as the dimensional accuracy of the castings, that’s why the measuring tools are made of high quality and strength which makes it expensive to use. Sometimes, the GAUGES or fixtures needed to check the dimensions are supplied to the CASTING facility by the CUSTOMER for better accuracy.

The correct answer is (a) True

The best I can explain: Heat and the head PRESSURE of MOLTEN metal can make a variation in the dimensions of casting, the heating and cooling of molten metal which results into expansion and CONTRACTION of it RESPECTIVELY, this changes the volume of a mould cavity and further results into the undesired dimensions of the casting.

Correct choice is (b) Slow-inaccurates

Explanation: According to the SUBJECT classification of MFFT, the CATEGORY of impulsives has the characteristics of spending LONG TIME and making more errors.