Influence of pre- and post-weld heating on weldability of modified 9Cr–1Mo(V–Nb) steel pipe under shielded metal arc and tungsten inert gas welding processes

Abstract

Influence of pre-and post-weld heating on weldability of modified 9Cr-1Mo(V-Nb) steel pipe under shielded metal arc and tungsten inert gas welding processes P. K. Ghosh and U. SinghWelding of modified 9Cr-1Mo(V-Nb) steel pipes has been carried out via shielded metal arc (SMA) and tungsten inert gas (TIG) welding processes. The weld joints have been produced using different preheating temperatures, followed by post-weld heat treatment (PWHT) at various temperatures. The microstructures of the weld and of the heat affected zone (HAZ) of the weld joints have been studied under the optical microscope and correlated with the preheating and PWHT. The average hardness of the weld and different regions of the HAZ, and tensile properties of the weld joints have also been studied and correlated with the preheating and PWHT. The tensile properties of the SMA and TIG weld joints produced using preheating and PWHT at various temperatures are compared and correlated with their microstructures. It is noted that a comparatively high preheating temperature of the order of 573 K is beneficial, and PWHT is necessary to reduce the susceptibility to cold cracking of weld joints of the present steel. The PWHT at 1123 K enhances ductility to fracture, but decreases the tensile strength of the base material, causing fracture of both the SMA and TIG weld joints from this region close to the HAZ. The tensile properties of SMA welds are found to be superior to those of the TIG welds, especially for PWHT at temperatures up to 1023 K. STWJ/403Extruded modified 9Cr-1Mo(V-Nb) steel pipes of outer diameter and wall thickness of the order of 50 and 6 mm respectively were welded via SMA and TIG welding processes. For both welding processes the root pass was carried out via autogenous TIG welding. The pipes, in sections of length 105 mm, were welded after an edge preparation to form a weld groove as shown schematically in Fig. 1. Before welding the sections of pipe were precisely matched with no root gap and held by a tack weld, followed by thorough cleaning of the weld groove by wire brushing. The job was held horizontally in a centring chuck of a stepless rotating table and a suitable fixture was arranged

Multipass pulsed current gas metal arc welding of P91 steel

“…1 The overall width of the HAZ remains between 3.0 and 3.5 mm in contrast to 4.5 to 5.0 mm as observed in GTAW and SMAW of P91 steels. 14 The reduction in HAZ width in GMAW-P can be considered significantly beneficial towards reducing the susceptibility to type IV cracking in welds of P91 steel. 1,13 The weld bead toughness for each sample weld is evaluated at three different locations as shown in Fig.…”

“…1,7,11,12 Several processes are attempted for joining of P91 steels depending on the original joint geometry, welding position, and the required rate of electrode deposition. 1,2,14,18,19 Gas tungsten arc welding (GTAW) could provide the joint toughness of around 100 J at room temperature although the lower rate of filler metal deposition remained a concern. 1,2,13,14,18,19 Conventional welding processes with consumable electrode could improve the deposition rate, but the welds commonly suffered from loss of alloying elements, low toughness, and high level of oxygen content and non-metallic inclusions.…”

“…1,2,14,18,19 Gas tungsten arc welding (GTAW) could provide the joint toughness of around 100 J at room temperature although the lower rate of filler metal deposition remained a concern. 1,2,13,14,18,19 Conventional welding processes with consumable electrode could improve the deposition rate, but the welds commonly suffered from loss of alloying elements, low toughness, and high level of oxygen content and non-metallic inclusions. 13,14,[18][19][20][21][22] Newell reported severe lack of fusion (LF) and oxide inclusions in conventional gas metal arc welding (GMAW) of P91 steels with a solid wire electrode.…”

Soldagem Gtaw Do Aço Sae 4130: Influência Do Pré-Aquecimento

“…Marcelino P. Nascimento (2011) verificou a influência da resistência à fadiga do aço AISI 4130 submetido a repetidos processos de reparação pelo método GTAW, observando que estes ciclos influenciam significativamente as propriedades mecânicas da junta [13].…”

Microstructural evolution of 9Cr–1Mo deposited metal subjected to weld heating

“…Controlling of welding conditions, e.g. welding heat input (Abe, 1984), preheating temperature (Ghosh and Singh, 2004;Roger, 1991), intercooling temperature (Totemeier * Corresponding author.…”