HARDNESS TEST EXPERIMENT # 4 Instructor: M.Yaqub

HARDNESS  Hardness is the ability of a material to resist against wear or indentation.  In HARDNESS TEST an indenter is used to penetrate in the sample by using a force.  Less penetration means, material is hard.  More penetration means, material is soft.  Different Hardness test because of different indenter and force.

HARDNESS TEST

BRINELLHARDNESS TEST  The brinell hardness testing equipment is used for the test.  The INDENTER is a mm Diameter (D) hardened steel ball.  Applied force (P) is maximum 250 kg.

ROCKWELL TEST  In this test, Rockwell hardness number HR can be read directly from the machine.  Several type of scales are available for Rockwell test, depends on the type of indenter and load.  See table on next slide for different scales use different type and size of indenter and force.

for example, Scale B uses 1/16 inch diameter steel sphere as an indenter and 100 kg force.

TEST PROCEDURE  Apply a minor load of 10 kg.  Then apply major load 60 to 150 kg according to the scale used for 4 to 5 seconds.  Release the major load only.  Machine will show the Rockwell Hardness Number HR on the machine.  All these operation will be done by machine automatically.  100 number means most hard and 0 means least hard  1 division represents a penetration of mm.

RELATION BETWEEN TENSILE STRENGTH AND HARDNESS

CONVERSION OF DIFFERENT HARDNESS SCALE