BS 6479:1984 pdf free.Method for determination and verification of the effective depth of carburized and hardened cases in steels.
BS 6479 describes a method for determining and verifying the effective depth of carburized and hardened cases in steels.
It is applicable to:
a) carburized cases including carbo-nitrided cases in steels, the depth of which is greater than 0.3 mm;
h) products or components which, when heat treated to final hardness, have a hardness of less than 450 HV at a distance of 3 x the effective case depth from the surface.
2 Definition
For the purposes of this British Standard the following definition applies.
2.1
effective case depth
the perpendicular distance between the surface and the layer having a Vickers hardness of 550 HV when measured using an applied test force of 9.807 N1
NOTE It is permissible t’o use test forces different from the reference test force 9.807 N, within the range 4.903 N to 49.03 N if agreed. Additionally, by agreement, the Knoop or superficial Rockwell methods for measuring hardness may be used, in which case the hardness limit value should be specified.
3 Designation
The effective case depth is designated by the letters DC, and is expressed in millimetres, in the area designated on a drawing of a part2, which can be either ground or not ground, e.g. 0.5 DC represents a carburized case having art effective depth of 0.5 mm.
4 Determination of effective case depth
4.1 Principle. The effective case depth is determined from the profile of hardness on a cross section normal to the surface. It is estimated graphically from a curve representing the variations in hardness as a function of the distance from the surface of the part.
4.2 Apparatus
4.2.1 Metaliographic laboratory equipn ent for preparing the surface to be examined.
4.2.2 Hardness test machine giving Vickers hardness values for test forces including between 4.903 N and 49.03 N.BS 6479 pdf download.