Rockwell Hardness Test

The Rockwell hardness test method consists of indenting the test material with a diamond cone or hardened steel ball indenter. The indenter is forced into the test material under a preliminary minor load FO usually I 0 kgf. When equilibrium has been reached, an indicating device, which follows the movements of the indenter and so responds to changes in depth of penetration of the indenter is set to a datum position. While the preliminary minor load is still applied an additional major load is applied with resulting increase in penetration . When equilibrium has again been reach, the additional major load is removed but the preliminary minor load is still maintained. Removal of the additional major load allows a partial recovery, so reducing the depth of penetration. The permanent increase in depth of penetration, resulting from the application and removal of the additional major load is used to calculate the Rockwell hardness number.

H R = E - e

FO = preliminary minor load in kgf

F1 = additional major load in kgf

F = total load in kgf

e = permanent increase in depth of penetration due to major load Fl measured in units of 0.002 mm

E = a constant depending on form of indenter: I 00 units for diamond indenter, 130 units for steel

ball indenter

HR = Rockwell hardness number

D = diameter of steel ball

CHARPY V NOTCH IMPACT TEST

CHARPY V NOTCH IMPACT TEST Object : To determine the amount of energy absorbed in fracturing a standardized test piece at a specified temperature. Method : A machined, notched specimen is broken by one blow from a pendulum. Because scatter occurs in the results, at least three specimens are used to assess the joint represented. Testing is carried out at a temperature specified in the appropriate application standard. Reporting Results: Location and orientation of the notch. Testing temperature. Energy absorbed in joules. Description of fracture appearance. Location of any defects. The Charpy impact test, measured in joules, is an assessment of TOUGHNESS. Transition temperature (curve) in steel.

ULTRASONIC TEST

ULTRASONIC TEST INTRODUCTION This method is used to test a variety of both metallic & non metallic products such as welds, forgings, castings, sheets, etc. It has an advantage of detecting sub-surface discontinues with accesses to only one side of the specimen. In this method beams of high frequency sound waves are introduced into the material being tested. The sound waves travel through the material with some loss of energy & are reflected back . This is detected & analysed to detect the presence of flaws. This test employs ultrasonic waves. These waves are mechanical waves that consist of oscillations or vibrations. METHOD TRANSMISSION SYSTEM This method employs two Transducers, one for sending & other for receiving the pulses. These may be short or continuous & are transmitted through the material. The result gets displayed on the CRO connected. The settings of the CRO can be adjusted with respect to time & distance. Prior to testing couplant is used to prov...

The Brinell Hardness Test

The Brinell Hardness Test The Brinell hardness test method consists of indenting the test material with a 10 mm diameter hardened steel or carbide ball subjected to a load of 3000 kg. For softer materials the load can be reduced to 1500 kg or 500 kg to avoid excessive indentation. The full load is normally applied for 10 to 15 seconds in the case of iron and steel and for at least 30 seconds in the case of other metals. The diameter of the indentation left in the test material is measured with a low powered microscope. The Brinell harness number is calculated by dividing the load applied by the surface area of the indentation. The diameter of the impression is the average of two readings at right angles and the use of a Brinell hardness number table can simplify the determination of the Brinell hardness. A well structured Brinell hardness number reveals the test conditions, and looks like this, "75 HB 10/500/30" which means that a Brinell Hardness of 75 was obtained us...

Mechanical Engineering

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