Abstract
Semi-solid billets of GH3536 alloy were prepared by semi-solid isothermal treatment of wrought superalloy method. GH3536 samples were soaked at several semi-solid temperatures (1350 °C, 1360 °C, 1364 °C, and 1367 °C) for 5–120 min. The effects of temperature and soaking time on the microstructure of GH3536 billets were studied. The results indicated that the microstructure was affected by coalescence mechanism, Ostwald ripening mechanism, and breaking up mechanism. Semi-solid microstructure of GH3536 alloy was composed of spherical solid particles and liquid phases, and the liquid phases affected the microstructure greatly. At 1350 °C, the coalescence mechanism was dominant at the early stage of isothermal treatment, then the Ostwald ripening mechanism played a major role for the longer soaking times. At higher temperatures, the breaking up mechanism occurred to form large irregular grains and small spherical grains. As the heating continued, the Ostwald ripening mechanism was dominant. However, at 1364 °C and 1367 °C, the solid grains had irregular shapes and large sizes when the isothermal time was 120 min. The optimum parameters for the preparation of GH3536 semi-solid billets were: temperature of 1364–1367 °C and soaking time of 60–90 min.
Highlights
Nickel-based superalloy is widely used for the manufacture of critical components of aero-engines owing to the excellent creep performance, corrosion resistance and abrasion resistance at high temperatures [1,2,3,4]
The average averagegrain grainsize sizeand andshape shapefactor facof of solid grains were significantly different under different heating parameters, which was tor solid grains were significantly different under different heating parameters, which mainly influenced by the coarsening mechanism and and refinement mechanism
In order to verify the feasibility of semi-solid billets of GH3536 alloy prepared by semi-solid isothermal treatment of wrought superalloy (SSITWS) method, extruded GH3536 samples were directly heated to semi-solid temperatures and soaked for 5–120 min
Summary
Nickel-based superalloy is widely used for the manufacture of critical components of aero-engines owing to the excellent creep performance, corrosion resistance and abrasion resistance at high temperatures [1,2,3,4]. The parts formed by casting methods have some defects such as segregation and porosity [6]. Semi-solid processing (SSP) is a novel technology to form near-net shaped components of metal materials [7]. It combines both the advantages of casting and forging, and can form parts with good comprehensive performance and complex geometry. The SSP method of high melting point alloys has not received widespread attention because of the high semi-solid temperatures. The requirements (suitable semi-solid temperature range) of SSP for metallic materials are not high, so it is possible to adopt SSP on nickel-based superalloys. It is meaningful to study the SSP of nickel-based superalloys
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