Abstract
In this study, the weld cold cracking sensitivity of TMCP steels with continuous casting process was investigated. Especially, the effect of center segregation on the weld cold cracking in the through-thickness direction was closely studied.
The results in this study were summarised as follows.
(1) In the rolling direction, the TMCP steels had high resistance to the weld colcd cracking.
(2) The TMCP steels are produced through the continuous casting and thermo-mechanical controlled rolling process. The segregation of P and Mn sometimes occured at the center of plate. It appeared that the center segregation, which was heated above the transformation temperature, result in the hardened region.
(3) Hydrogen delayed cracking initiated in the hardened regions after welding under the stress (especially the through-thickness direction stress). It was caused by the hardened structure and stress concentration at inclusions in this region.
(4) The fracture surfaces in the regions were terrace feature and contained hydrogen induced intergranular and quasi-cleavage fractures with inclusions.
