ISO 4498:2010 pdf free download – Sintered metal materials, excluding hardmetals一Determination of apparent hardness and microhardness.
4.5 The measurement of microhardness shall not be valid if the test surface is not perpendicular to the indenter axis. Non-perpendicularity will be probable with isotropic materials, if one leg2) of the diagonal is noticeably longer than the other leg2) (Vickers or Knoop microhardness). The specimen for microhardness testing shall be positioned on the supporting table, or presented in such a way that the test surface is perpendicular to the direction of the test force, otherwise the indentation will be distorted. This position shall be maintained during the entire test.
5 Test procedures
5.1 Procedure I — Determination of apparent hardness
5.1.1 The tests shall be carried out in accordance with the requirements of ISO 6506-1, ISO 6507-1 or ISO 6508-1, but also with the additional requirements given in 5.1.2 to 5.1.5.
5.1.2 The hardness class to which a test piece belongs shall be determined by Vickers hardness testing using a test force of 49,03 N (HV 5). The test conditions shall then be selected from Table A.1 according to the class determined. Details of the conditions for the Rockwell test are given in Table A.2.
In some cases, particularly with solution-hardened PM (powder metallurgy) materials, it is advantageous to determine hardness values on the HRB scale using a hardmetal ball indenter. In these cases, results are then denoted by HRB and are used up to a maximum value of HRB 115.
If, after the initial HV 5 test, there is any doubt as to the hardness class to be chosen, the lower class shall be selected.
When a material specification covers more than one hardness class, the test shall be conducted under the conditions appropriate to the lower hardness limit given in the specification.
5.1.3 For some test pieces, it will be necessary to use smaller test forces than those specified in Tables A.1 and A.2, in order to meet the requirements of ISO 6506-1, ISO 6507-1 or ISO 6508-1. This will be particularly so
— on thin test pieces,
— for test pieces of small cross-sectional area,
when the designated test area is very small, and
— when the test piece or its mount is likely to be distorted.
When such test conditions are necessary, the details shall be agreed between the customer and the supplier. It should be noted that, in these circumstances, the scatter of the results will be greater than under normal test conditions and that the value obtained will be less representative of the state of the material since the indentation will be very small.
5.1.4 When determining Vickers hardness, an indentation is not valid if
— it does not have clearly defined corners,
— the edges are distorted (inwards or outwards), or
— the lengths of the diagonals are substantially different.
5.1.5 Five valid indentations shall be made and the corresponding hardness values calculated (or simply read in the case of Rockwell testing). Another procedure for treatment of results is permitted, by agreement between the customer and the supplier.
5.2 Procedure 2— Determination of microhardness
5.2.1 When determining the microhardness of surface-treated material (as described in 1.3), reference shall be made to ISO 4516 for test conditions (precautions, load, velocity and direction of application of the force). Figure 1 shows an indication of the force to be used as a function of the thickness of material which has undergone surface modification by one of the methods listed in 1.3.