AS NZS 2205.5.1:2019 Methods for destructive testing of welds in metal
5 Principle
Macroscopic and microscopic examination is used to reveal the macroscopic or microscopic features of a welded joint, usually by the examination of transverse sections.This is done by visual and/or optical examination of the prepared surface, before or after etching.
6 Purpose of the test
The purpose of macroscopic and microscopic examinations is to assess the structure (including grain structure, morphology and orientation, precipitates and inclusions) independently and/or in relation to various cracks and cavities. Sections can also provide a record of sample shape in the planes of the section. Table 1 gives guidance on the assessment of features which can be detected by macroscopic and microscopic examination.
7 Removal of test specimens
Test specimens are generally oriented perpendicular to the weld axis (transverse section), including the weld deposit and heat affected zones on both sides of the weld. However, test specimens may also apply to other orientations.
The location, orientation and number of test pieces should be specified prior to testing, for example by reference to an application standard.
8.1 General
The following information shall be given:
一parent metals and welding consumables;
一object of the test;
一composition/name of the etchant;
一surface finish (see 8.3);
一etching methods (see 8.4);
一etching time;
一additional measures (see 8.6);
一any additional requirements.
8.2 Test specimen preparation
The test specimen shall be prepared for examination by cutting, mounting, grinding and/or polishing and/or etching as appropriate (see ISO/TR 16060). The surface to be examined shall not be adversely influenced by these processes.
8.3 Surface finish
The requirement for surface finish depends on aspects such as
一type of examination (macroscopic or microscopic);
一type of material;
一documentation (such as photographs).
NOTE Details of the grinding and polishing media and methods of grinding and polishing are given in ISO/TR 16060.
8.4 Etching methods
The method of etching shall be specified prior to etching. The most common methods are
一etching by immersing the test specimen in the etchant;
一etching by swabbing the surface of the test specimen;
一electrolytic etching.
Other methods may be used but should be specified, e.g. by reference to an application standard.
When etching is completed, the test specimen should be washed and dried.