This study investigates the hot-cracking susceptibility of the Ni-based superalloy N06617 during welding through the integration of systematic experiments and thermo-mechanical coupled finite element simulations. Emphasis is placed on evaluating the relationship between strain rate within the brittle temperature range (BTR) and liquation-cracking susceptibility. Welding tests with different welding speeds, interpass temperatures, and cooling conditions were conducted for model validation and crack comparison, while the effect of heat input was investigated numerically. Three characteristic indicators—crack-susceptible duration (Δt), instantaneous strain at 1220 °C (ε), and average strain rate (dε/dt)—are defined to evaluate crack susceptibility. Results show that the average strain rate within the BTR increases with welding speed and interpass temperature, is further promoted by intensive water cooling, and decreases with increasing heat input. Experimental macrographs show that the observed cracking behavior is consistent with the calculated strain-rate trends, supporting the use of the average strain rate as a comparative indicator of liquation-cracking susceptibility under the investigated conditions.
Co-Cr-Mo components fabricated by the laser powder bed fusion (PBF-LB/M) additive manufacturing method are employed in aero-engine applications owing to their excellent high-temperature mechanical strength and corrosion resistance. In this study, nine different heat treatment (HT) conditions (750, 900, and 1050 °C, each for 1, 3, and 6 h of duration) were applied to as-built (with PBF-LB/M) Co-Cr-Mo alloy specimens, and their high-temperature oxidation behavior was evaluated through thermogravimetric analysis (TGA) at 800 °C for 20 h in synthetic air mixture of O2/N2 (20/80 vol.
The effect of aluminum addition on the phase evolution, microstructure, densification, hardness, and dry sliding wear behavior of powder metallurgy processed 316L stainless steel was investigated. Powder mixtures containing 0, 5, 10, and 20 wt.
Ti6Al4V titanium alloy is widely used in critical load-bearing components in the aerospace industry owing to its high specific strength and excellent high-temperature mechanical properties. However, under high-speed milling conditions, the low thermal conductivity of the material leads to severe heat accumulation in the cutting zone, significantly intensifying the thermo-mechanical coupling induced by cutting deformation and interfacial friction. As a result, surface roughness deterioration and subsurface damage are readily induced, thereby restricting the achievement of high-quality machining. Tool geometric parameters, including rake angle, clearance angle, and nose radius, play a decisive role in governing surface integrity and subsurface damage evolution by regulating stress distribution, frictional conditions, and material deformation behavior in the cutting zone. Accordingly, a single-factor experimental approach combined with finite element numerical simulations was employed to systematically investigate cutting force, milling temperature, surface roughness, and characteristics of the work-hardened layer during high-speed milling of Ti6Al4V under varying rake angles, clearance angles, and edge radii. The results indicate that a moderate increase in rake angle and clearance angle effectively reduces cutting force and milling temperature. The optimal overall machining performance was achieved at a rake angle of 0°, a clearance angle of 12°, and a nose radius of 3 mm, resulting in a maximum reduction of 56
AA2014 is a high-strength precipitation-hardenable Al-Cu-Mg-Si alloy used mainly as structural components of launch vehicles. Its widespread adoption in fusion-welded structures has, however, been limited by a strong susceptibility to solidification cracking, liquation cracking in the partially melted zone (PMZ) and post-weld softening. In the present work, 2 mm thick Al-clad AA2014-T6 sheets were joined in a square-butt configuration by Tungsten Inert Gas (TIG) welding under both continuous (CTIG) and pulsed (PTIG) current modes, with three filler wires of contrasting chemistry AA2319 (Al-6.25Cu), AA2014 (Al-4.3Cu-Mg-Si) and AA4043 (Al-5.1Si). Welded coupons were qualified by radiographic and dye-penetrant inspection, and characterized in the as-welded as well as in T4 and T6 post-weld heat-treated conditions through optical microscopy, SEM/EDS and uniaxial tensile testing. No solidification cracking was detected in any of the six filler and current combinations. Fusion-zone grain size ranged from 17 to 21.5 µm and correlated with the titanium content of the filler wire (0.025 to 0.20 wt.
