Showing papers by "Hiroyuki Kokawa published in 1993"
TL;DR: In this article, the tensile properties and microstructures of the weld metals were examined and the fractographs suggest that only the base metal and high-nitrogen weld metal clearly show dimple patterns.
Abstract: Summary Type 329J1 duplex stainless steel was welded by gas tungsten arc welding in argon‐nitrogen mixed gas atmospheres. The tensile properties and microstructures of the weld metals were examined. The nitrogen content increases and the ferrite content decreases with increasing nitrogen partial pressure of the atmosphere. The ferrite content linearly decreases with an increasing nitrogen content. The tensile strength and elongation of the weld metal produced in the argon atmosphere are much lower than those of the base metal, but they increase with an increasing nitrogen content and approximate those of the base metal at around 0.4 mass% nitrogen content. The fractographs suggest that only the base metal and high‐nitrogen weld metal clearly show dimple patterns. The tensile‐tested base metal and high‐nitrogen weld metal have complex crack paths, whereas the other weld metals have relatively straight paths. The tensile properties of the weld metal are affected by the ferrite content and chromium nitride.
3 citations
TL;DR: In this article, the effect of ambient pressure on the melting rate of electrode wire and the geometry, chemical compositions and mechanical properties of weld metals were studied, and the results obtained are as follows:
Abstract: Mild steel was welded in pressurized CO2 atmospheres in the pressure range from 1 to 30 atm using a solid wire of 16 mm dia The effect of ambient pressure on the melting rate of electrode wire, and the geometry, chemical compositions and mechanical properties of weld metals were studiedThe results obtained are as follows:1) The melting rate of an electrode wire increases with the increase of ambient pressure up to a certain pressure2) The bead width decreases with the increase of ambient pressure3) The penetration depth and fused area of base metals increase with increasing the ambient pressure up to a certain pressure4) The melting rate of electrode wire and bead geometry appear to be affected with the metal transfer mode of electrode wire in pressurized CO2 atmospheres5) Oxygen content of weld metals increase with the increase of ambient pressure6) The charpy impact values of weld metals decrease with increasing the ambient pressure