Testing of Electrodes
All electrode standards describe in great detail the procedures for executing all-weld tensile and impact test. Some of them also describe methods for determining weld deposition efficiency and hydrogen in the weld deposit. The tensile strength, yield strength and elongation values obtained in the tensile test, and the values obtained in the other two tests provide the symbols for the coding of an electrode.
All-weld metal means weld deposit which is not diluted by the base metal. In all-weld tensile and impact tests, the test specimens are so prepared that the area which is subjected to test is pure, undiluted weld metal.
The electrode standards also prescribe supplementary tests which are not related to the code symbols, but are meant to evaluate the performance of an electrode and its suitability for welding certain grades of steel. These tests in various combinations are used for the quality control of production batches and their acceptance by consumers as indicated in the standards. The various tests included (3) in each standard are indicated in Table 4.16.
Table 4.16. Standard tests for electrodes
While IS : 815 deals with classification and coding, IS : 814 covers specification and testing. Hence the tests are distributed among them.
ISO 2401 describes this test.
ISO 3690 describes the method.
AWS describes coating moisture test as a substitute for diffusible hydrogen test.
DIN 8572 describes the method.