The Lehigh Restraint Gracking Test of High Tensile Mn-Si Steel

Abstract

The purpose of this test was to examine by means of the Lehigh restraint cracking test the effects of type of steel and electrode on crack susceptibility of high strength steel. The Lehigh restraint test is a butt-weld cracking test for comparing quantitatively the degree of restraint at which crack occurs. The results obtained in this test were as follows;
1) The steel Y6B was most crack-insensitive of all steels tested.
2) There seems to exist a linear relationship between the percentage of crack and the value of Tremlett's equivalent carbon, Ceq, which does not contain a term of silicon content.
3) Among those electrodes used LH29 had greater crack susceptibility. The order of the other electrodes was as follows ; LB76, FL76, SL76, HTO52, the latter less cracking. Since this test was performed only once for each condition the effect of restraint on crack susceptibility was not obvious and therefore the degree of critical restraint could not be obtained. Consequently, the mean value of percentages of crack was used in the analysis of experimental results.