Assessment of resistance of low-alloy steels to reheat cracking using Vinckier test

Abstract

In recent years, a considerable volume of work has been carried out using laboratory tests in attempts to relate susceptibility to heat-affected zone cracking to the mechanical properties of materials. In this paper, the authors describe an investigation in which a welding test was used to assess reheat cracking susceptibility and compare the results with previous work on thermally simulated specimens. The welding test was originally devised by Vinckier and simply utilizes the difference between the coefficients of thermal expansion shown by ferritic and austenitic materials during the stress-relieving cycle,. these materials are welded so as to apply the strain to a waisted ferritic specimen. A range of steels has been used, including (a) material which shows a high incidence offailure, (b) high-quality Cr-Mo-V, and (c) both good- andpoor-quality 2Cr-Mo. It is shown that the test can be used to provide a comparative measure of a material's susceptibility to the initiation andpropagation of reheat cracks. The test was also used to study in detail the morphology of the crack surface and to compare it with that inplantfailures. Advantages and limitations of the test together with suggested improvements are discussed.