278 sum- TI:STS. 



SHOP TESTS OF IKON AND STEEL. 



144- In addition to the tensile, compressive, and 

 cross-breaking tests which have been described, the pur- 

 chasers of iron and steel for structural purposes are in the 

 habit of insisting upon certain other tests being under- 

 gone by samples of the metal. These further tests are 

 such as can be carried out without the help of any special 

 machinery by means of ordinary appliances such as are 

 available in any forge. Many of these tests are also 

 insisted upon by such authorities as the Admiralty, 

 Lloyd's, and the Board of Trade. These include hot and 

 cold bending tests, drifting tests, drop tests, and smithy 

 tests. 



145. Cold Bending Tests. There is no more useful 

 test applied to wrought iron and steel than the 

 bending test. It is easily and quickly performed, and it 

 can be carried out in the manufacturer's works. This 



_t .^ 



FIG. 141. ADMIRALTY COLD BENDING TEST FOB WROUGHT IRON. 



test must not be confused with the cross-breaking tests 

 which have already been described. It consists in simply 

 bending a strip of the materal, either until fracture takes 

 place and at the same time noting the angle to which it 

 has been bent or in bending the strip through a specified 

 angle, to a certain radius of curvature, and noting whether 

 or not the outer fibres have shown any tendency to crack 

 or fracture. If the material is satisfactory from the point 

 of view of this test, there should be no such cracking of 

 the metal. The actual testing may be effected best by 

 means of an hydraulic press, the bending being made over 

 a mandrel of given diameter, or a steam or sledge 

 hammer may be used, preferably the former: Bending 

 under a gradually applied force is far more satisfactory 

 than bending under blows. In some cases screw vices 

 are used. 



Unfortunately these tests are not sufficiently stan- 

 dardised to make them very useful in applying a rigid 



