Hardening (metallurgy)

About: Hardening (metallurgy) is a research topic. Over the lifetime, 25584 publications have been published within this topic receiving 376012 citations.

Does partial melting reduce the creep strength of the upper mantle

Abstract: The seismic low-velocity zone has been thought to correspond to a zone of partial melting that significantly reduces the creep strength, making it possible for the plates to decouple from the underlying mantle1,2. This view is examined here in light of recent experimental results which show that water has more effect on the creep strength of olivine3–6 than does partial melting7,8 and that the former depends on the fugacity of water5,6. When there is a limited amount of water, partial melting will result in depletion of water from olivine, and therefore have a hardening, rather than a softening, effect.

High Strength and Ductility of Additively Manufactured 316L Stainless Steel Explained

Abstract: Structure–property relationships of an additively manufactured 316L stainless steel were explored. A scanning electron microscope and electron backscattered diffraction (EBSD) analysis revealed a fine cellular-dendritic (0.5 to 2 μm) substructure inside large irregularly shaped grains (~ 100 μm). The cellular structure grows along the 〈100〉 crystallographic directions. However, texture analysis revealed that the main 〈100〉 texture component is inclined by ~15 deg from the building direction. X-ray diffraction line profile analysis indicated a high dislocation density of ~1 × 1015 m−2 in the as-built material, which correlates well with the observed EBSD microstructure and high-yield strength, via the traditional Taylor hardening equation. Significant variations in strain hardening behavior and ductility were observed for the horizontal (HB) and vertical (VB) built samples. Ductility of HB and VB samples measured 49 and 77 pct, respectively. The initial growth texture and subsequent texture evolution during tensile deformation are held responsible for the observed anisotropy. Notably, EBSD analysis of deformed samples showed deformation twins, which predominately form in the grains with 〈111〉 aligned parallel to the loading direction. The VB samples showed higher twinning activity, higher strain hardening rates at high strain, and therefore, higher ductility. Analysis of annealed samples revealed that the observed microstructures and properties are thermally stable, with only a moderate decrease in strength and very similar levels of ductility and anisotropy, compared with the as-built condition.

Description of tantalum deformation behavior by dislocation mechanics based constitutive relations

Abstract: Dislocation mechanics based constitutive equation constants are determined for temperature, strain rate, work hardening, and polycrystal grain size influences on the deformation behavior of various tantalum materials. An analysis of the maximum load point strain provides a useful method of determining the work hardening constants. Different athermal stress constants and thermal activation related constants are obtained for certain groupings of the different tantalum materials. The variations are correlated with the annealing history of the materials and related to dislocation model parameters involved in the thermal activation strain rate analysis. Computed tantalum deformation results based on these constants are shown to agree with Gourdin’s reported expanding ring test measurements and with the deformed shape of a Taylor cylinder impact test specimen.