Filler metal

About: Filler metal is a research topic. Over the lifetime, 11152 publications have been published within this topic receiving 86590 citations.

Hot cracking in tungsten inert gas welding of magnesium alloy AZ91D

Abstract: Plates of 3–5 mm in thickness were extracted from an AZ91D ingot and then butt joints of the plates were produced using tungsten inert gas (TIG) welding method. The TIG arc was also used to deposit welding beads on some of the thin plates. No cracking was found in the butt joints. However, hot cracking was always observed to propagate from the heat affected zone (HAZ) under the welding bead into the weld metal right after a welding bead was deposited on the thin plate. Metallographic and fractographic evidence was obtained to show that the hot cracking is 'liquation cracking' in the partially melted HAZ under the high thermal stresses. In the butt joints, the weld metal has the finest grains, highest strength and best ductility, and the HAZ was found to be the 'weakest link'.

Elucidation of the effect of welding speed on melt flows in high-brightness and high-power laser welding of stainless steel on basis of three-dimensional X-ray transmission in situ observation

Abstract: This research was performed with the objective of clarifying the effect of welding speed on melt flows during melt-run welding of SUS304 stainless steel plates with a 6-kW power laser beam on the basis of three-dimensional X-ray transmission in situ observation. As welding speed increased from 25 to 250 mm/s, three kinds of welds characterized by porosity formation and no defects or underfilling due to spatters were produced. The average and the maximum values of measured melt flow velocity were 3 and 10 times higher than the welding speed, respectively. Two kinds of circulation flows at the inlet or the tip of a keyhole were confirmed to control heat transfer in a molten pool. It was found that the circulation flows were so sensitive to the welding speed that bubbles resulting in porosity or spatters were often formed. According to X-ray observation of the formation of spatters with tungsten carbide (WC) tracers, as the melt flow rose along the keyhole wall, the velocity was accelerated from 0.24...

Effects of laser brazing parameters on microstructure and properties of TiNi shape memory alloy and stainless steel joint

Abstract: Laser brazing has been applied for joining TiNi shape memory alloy (SMA) and stainless steel (SS) using the silver-based filler metal with composition of 52%Ag, 22%Cu, 18%Zn and 8%Sn (wt.%) and effects of laser brazing parameters has been investigated. The filler metal has good wettability on both TiNi SMA and SS. The brazing seam metal consists of α-Ag solid solution, α′-Cu solid solution surrounded by the α-Ag and eutectic structures. Heat affected zones (HAZs) of TiNi SMA and SS are comprised of B2 and B ′ 19 phases and austenite phase, respectively. Increasing laser output power and brazing time resulted in the grain coarsening and reducing the microhardness value in the HAZs. The laser output power and brazing time have effects on the superelasticity (SE) and shape memory effect (SME) of the TiNi SMA HAZ. With increasing laser output power and brazing time from 50 W/10 s to 70 W/20 s, the residual strain (ɛu) at room temperature in the HAZ increased from 0.37% to 2.22% and the shape recovery rate (ψ) at 100 °C decreased from 91.6% to 62.1%. The deterioration of SE and SME in TiNi SMA HAZ could be attributed to the coarse-grained structures. It is favourable to decrease laser output power and brazing time for improving both SE and SME of TiNi SMA HAZ.