High-temperature mechanical properties of laser welds in Co-base superalloy and its improvement by laser surface melting

Assessment of the effects of heat input on microstructure and mechanical properties in laser beam welded Haynes 188 undermatched joints

“…The k values for the major alloying elements (Cr, Fe, Ni, Co, Mn, and W) calculated in this study are close to unity, indicating that a tendency for segregation is not expected. These values of k are in good agreement with the findings of Makino et al [17], who investigated high temperature mechanical properties of laser beam welding and tungsten inert gas (TIG) welding used 0.9 mm diameter Haynes 188 compatible filler wire. In Makino et al [17] study alloying element concentrations obtained by both welding processes (TIG and LBW) were similar to each other although the expected cooling rates in the welds were significantly different.…”

“…However the lower the k value (ko1), the lower the concentration of the particular alloying element in the dendrite core regions [35]. Table 5 lists the calculated values of k from the samples #1 and #9 from this study and others [17] previously reported for Haynes 188. The k values for the major alloying elements (Cr, Fe, Ni, Co, Mn, and W) calculated in this study are close to unity, indicating that a tendency for segregation is not expected.…”

“…Similarly, Hongxiao et al [14] and Kumar and Shahi [15] described the importance of the applied heat input on the weld microstructure, fusion zone shape, surface quality and mechanical properties of stainless steel joints. Although there have been a number of studies on the welding process of various alloy systems, there have been only two reports on superalloy Haynes 188 [16,17]. The primary aim of this study was to evaluate the effect of laser beam power on the microstructure and mechanical properties of laser beam welded superalloy Haynes 188.…”

Influence of Yb:YAG Laser Beam Parameters on Haynes 188 Weld Fusion Zone Microstructure and Mechanical Properties

“…[17] For the whole temperature range of measurement during the mechanical tests, the yield strength of the welds was almost the same as that of the parent metal. The maximum strength and ductility were 95 and 60 pct of those of the parent metal, respectively.…”

“…Odabasi et al observed by optical microscopy no HAZ or cracks at the interface of the base material (BM) with the FZ, but noted a gradient in hardness between these two zones over several hundred microns. Electron probe micro analysis (EPMA) measurements performed by Makino et al [17] showed that the FZ composition was identical to that of the BM after laser welding. There was thus no loss of chemical elements by spraying.…”