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.

NDT ( NON DESTRUCTIVE TESTING )

NDT (NON DESTRUCTIVE TESTING) :- Non Destructive Testing in great variety are in world wide used to detect variations in structure, minute changes in surface finish, the presence of cracks or other physical discontinuities, measure the thickness of materials and coatings and to determine other characteristics of industrial products. REASON'S FOR THE USE OF NDT: "NDT" is used by the manufacturers for the following reasons: 1. To ensure product reliability. 2. To make profit for the user. a) To ensure customer satisfaction b) To aid in better product reliability. c) To control the manufacturing processes. d) To lower the manufacturing costs. e) To maintain uniform quality level. SOME OF THE MOST COMMON NDT METHODS ARE : 1.VISUAL ...

RADIOGRAPHY TEST

RADIOGRAPHY TEST INTRODUCTION : Industrial radiography is a nondestructive test method that uses X-rays or Gamma rays to show the presence and certain characteristics of internal discontinuities in solid materials. The method is based on the ability of X-ray or Gamma-ray radiation to penetrate solids, to a degree that varies with such factors as wave length of the radiation, and type and thickness of the material part of the radiation penetrates the material and part is absorbed. The amount absorbed and the amount transmitted are a function of the thickness of the material. Where a void or discontinuity exists, there is essentially less material to absorb the radiation. This creates a different in absorption, a difference that registers on photographic emulsions. The result is a shadow picture called a radiography Radio-graphic Sources : The common gamma ray radio-graphic sources : Cobalt - 60 Cesium - 137 Iridium - 192 Thulium - 170 Gamma Ray Radiography : Gamma rays ar...

Mechanical Engineering

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