Heat-affected zone

About: Heat-affected zone is a research topic. Over the lifetime, 18787 publications have been published within this topic receiving 231744 citations.

Effects of activating flux on arc phenomena in gas tungsten arc welding

Abstract: Dramatic increases in the depth of weld bead penetration have been demonstrated by welding stainless steel using the gas tungsten arc (GTA) process with activating fluxes consisting of oxides and halides. However, there is no commonly agreed mechanism for the effect of flux on the process. In order to clarify the mechanism, behaviour of the arc and weld pool in the GTA process with activating flux was observed in comparison with a conventional GTA process. A constricted anode root was found in the GTA process with activating flux, while a diffuse anode root was found in the conventional process. Furthermore, it is suggested that these anode roots are strongly related to metal vapour from the weld pool, which is also related to temperature distributions on the weld pool surface.

Effect of Boron on Intra-granular Ferrite Formation in Ti-Oxide Bearing Steels

Abstract: The effect of B on microstructure and toughness at the heat affected zone after welding thermal cycle simulations has been investigated in steels containing titanium oxide particles. The titanium oxide is identified as Ti2O3 with cation vacancies, which contribute to preferential nucleation of MnS and TiN precipitates on Ti2O3. The Mn-depleted zone is formed around Ti2O3 after the precipitation of MnS. The Ti2O3, particles with TiN and Mn-depleted zone act as preferential nulceation sites for intra-granular ferrite. The segregation of B at austenite grain boundaries suppresses effectively the nucleation of grain boundary ferrite. Ferrite nucleation at the interface between Ti2O3 and austenite matrix is not affected by B addition because of B-depleted zone arisen from the diffusion of segregated B into Ti2O3 via cation vacancies. Consequently the B addition to steels with Ti2O3 promotes the formation of fine intra-granular ferrite grains so that the toughness in heat affected zone is improved even after large heat input welding.

High quality welding of stainless steel with 10 kW high power fibre laser

Abstract: The objectives of this research are to investigate penetration characteristics, to clarify welding phenomena and to develop high quality welding procedures in bead on plate welding of type 304 austenitic stainless steel plates with a 10 kW fibre laser beam. The penetration depth reached 18 mm at the maximum at 5 mm s−1. At 50 mm s−1 or lower welding speeds, however, porosity was generated at any fibre laser spot diameter. On the other hand, at 100 mm s−1 or higher welding speeds, underfilling and humping weld beads were formed under the conventionally and tightly focused conditions respectively. The generation of spatters was influenced mainly by a strong shear force of a laser induced plume and was greatly reduced by controlling direction of the plume blowing out of a keyhole inlet. The humping formation was dependent upon several dynamic or static factors, such as melt volume above the surface, strong melt flow to the rear molten pool on the top surface, solidification rate and narrow molten poo...