Studies On Microstructure And Property Of GH4169 Argon-arc Welding Joint

As one kind of Ni-based wrought superalloy, GH4169 can is manufactured into many complex parts and is wildly used in following fields, such as astronavigation, atomic energy, oil and so on, at the temperature range of -253-700℃. This thesis reports an investigation on the microstructure and physical properties of base metal and Argon-arc welding joint of Ni-based GH4169 superalloy.GH4169 superalloy plates of 1.5mm-thickness were jointed by Argon-arc welding and part of joints was rolling-treated. Tensile tests at room temperature and 650℃, blend, stress-rupture and microhardness tests were finished according to involved astronavigation standards. Physical property, fracture appearance and microstructure of the joints were studied by means of optical, scanning electron microscopes, energy spectrometer.The fracture of the alloy is featured with dimple in tensile test both at room and high temperature, mixed mechanism fracture, existing both dimples and tear ridges, is labeled with the alloy in creep rupture. The position where the joints got cracking almost at fusion area or welded seam at 650℃ while cracked at base metal at room temperature. Tensile fracture of joint is dimple at room temperature while conchoidal fracture belongs to high tensile and inter-granular and quasicleavage are with stress-rupture tensile. Stress-rupture strength of the joints is equivalence to the value the base metal has, while plasticity gets deteriorating both at room and high temperature. Microhardness value in HAZ is higher than that in welded zone. Physical properties of the rolled joint are better than unrolled joints'. Austenite microstructure of the alloy is featured with banding at room temperature while regular pattern through long-time high temperature, and...