| 1 | Microstructural softening induced adiabatic shear banding in Ti-23Nb-0.7Ta-2Zr-O gum metal显示文摘Ti-23Nb-0.7Ta-2Zr-O gum metal(GM)is an attractive candidate material for applications that require superior mechanical properties.In our earlier investigation of the GM[1],geometrical softening and the generation of adiabatic shear bands(ASBs)were proposed as primary reasons for the documented anisotropic impact response.In the present study,electron backscattered diffraction(EBSD)analysis reveals two different deformed microstructures,i.e.,deformed ultrafine grains(UFGs)and dynamically recrystallized UFGs,formed in the ASBs of GM samples processed by extrusion equal channel angular pressing(ECAP),respectively.Additional calculation of temperature rise during dynamic compression suggests that the above microstructure differences in the ASBs was originated from their different maximum ASB temperatures(608 K for extruded GM and 1159 K for ECAP-processed GM).Moreover,our calculation on the temperature at the onset of ASBs indicates that microstructural softening is the primary cause for the development of ASBs in both extruded GM(321 K)and ECAP-processed GM(331 K). | Silu Liu Y.Z.Guo Z.L.Pan X.Z.Liao E.J.Lavernia Y.T.Zhu Q,M,Wei Yonghao Zhao | 2020 | Journal of Materials Science & Technology2020，54，19： | 2 |
| 2 | On the microstructure and texture evolution in 17-4 PH stainless steel during laser powder bed fusion: Towards textural design显示文摘Additive Manufacturing (AM) of metals allows the production of parts with complex designs, offeringadvanced properties if the evolution of the texture can be controlled. 17-4 precipitation hardening (PH)stainless steel is a high strength, high corrosion resistance alloy used in a range of industries suitable forAM, such as aerospace and marine. Despite 17-4 PH being one of the most common steels for AM, thereare still gaps in the understanding of its AM processing–structure relationships. These include the natureof the matrix phase, as well as the development of texture through AM builds under different processingconditions. We have investigated how changing the laser power and scanning strategy affects the microstructure of 17-4 PH during laser powder bed fusion. It is revealed that the matrix phase is δ-ferritewith a limited austenite presence, mainly in regions of the microstructure immediately below melt pools.Austenite fraction is independent of the printing pattern and laser power. However, reducing the timebetween adjacent laser passes during printing results in an increase in the austenite volume fraction.Another effect of the higher laser power, as well as additional remelting within the printing strategy, isan increase in the average grain size by epitaxial ferrite grain growth across multiple build layers andthe development of a mosaic type microstructure. Changes to the scanning strategy have significant impacts on the textures observed along the build direction, while (100) texture along the scanning directionis observed consistently. Mechanisms for texture formation and the mosaic structure are proposed thatpresents a pathway to the design of texture via AM process control. | M.S.Moyle N.Haghdadi X.Z.Liao S.P.Ringer S.Primig | 2022 | Journal of Materials Science & Technology2022，，22： | 0 |
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