This standard gives an introduction to the fundamentals of hot cracking in weld metals and parent alloys, and briefly describes the tests available for arc welding processes. — Part 2: Self restraint tests — specifies the tests which should be used to assess the susceptibility to hot cracking of weld metals. The strains to cause cracking are provided by the restraint of the weldment. — Part 3: Externally loaded tests — describes the tests which can be used to assess the susceptibility to hot cracking of parent alloys and weld metals. The strains to cause cracking are provided by external loading on the test specimen. NOTE The tests in part 3 require the use of non-standardised proprietary equipment and different laboratories use various procedures, test conditions and specimen sizes, therefore reproducibility within a given laboratory is usually good but differences between laboratories are sometimes found.