Research on the Nanobainitic Features Formed in the Ultra-low Carbon Steel Non-Containing Nb and Ti Elements

The XRD analysis, microstructure observation and mechanical test were used to investigate the phase composition, micromorphology and mechanical properties of the intermediate transformation products in an ultra-low carbon steel non-containing Nb and Ti elements. The results showed that even without the presence of Nb and Ti alloy compounds, the experimental steel still exhibited good Rockwell hardness level. When the steels were held for a shorter times at 450°C, its Rockwell hardness under stayed 100s after plastic deformation at 850°C was higher than that under cooled directly because the 100s-stayed process was benefit to the formation of nanobainite. However, when the steels were held over 30min at 450°C, its Rockwell hardness under stayed 100s were close to that of non-stayed steel

Effect of austenitizing temperature on the bainitic transformation in a high-carbon high-silicon steel

The effect of austenitizing temperature (880 - 1000°C) on the incubation period and bainitic transformation in steel 0.88% C - 1.35% Si - 1.0% Cr - 0.43% Mn is studied by the methods of x-ray diffraction and optical and transmission electron microscopy. The effect of the austenitizing temperature on the temperature and incubation period of the nose of the C-curve of the bainitic transformation is determined. The influence of a 20-min hold at 250°C after the austenitizing on the bainitic structure is studied

Characterization of a Nanocrystalline Structure Formed by Crystal Lattice Transformation in a Bulk Steel Material

The formation of nanocrystalline structures in bulk metal materials is of great significance for both investigating the structural features of nanocrystalline materials and enhancing the value of bulk metal materials in engineering applications. Herein, we report a nanocrystalline structure formed by lattice transformation in a three-dimensional bulk metal material. We characterized its phase composition, three-dimensional features, and boundary structure. This nanocrystalline structure had microscale length and height and nanoscale width, which gave it a “nanoplate„ structure in three-dimensional space. We observed edge dislocations in the interior of the nanocrystalline structure. A unique transitional boundary that contributed to maintaining its nanoscale size was found at the border between the parent phase and the nanocrystalline structure

Effect of Sm Doping on the Microstructure, Mechanical Properties and Shape Memory Effect of Cu-13.0Al-4.0Ni Alloy

The effects of rare earth element Sm on the microstructure, mechanical properties, and shape memory effect of the high temperature shape memory alloy, Cu-13.0Al-4.0Ni-xSm (x = 0, 0.2 and 0.5) (wt.%), are studied in this work. The results show that the Sm addition reduces the grain size of the Cu-13.0Al-4.0Ni alloy from millimeters to hundreds of microns. The microstructure of the Cu-13.0Al-4.0Ni-xSm alloys are composed of 18R and a face-centered cubic Sm-rich phase at room temperature. In addition, because the addition of the Sm element enhances the fine-grain strengthening effect, the mechanical properties and the shape memory effect of the Cu-13.0Al-4.0Ni alloy were greatly improved. When x = 0.5, the compressive fracture stress and the compressive fracture strain increased from 580 MPa, 10.5% to 1021 MPa, 14.8%, respectively. When the pre-strain is 10%, a reversible strain of 6.3% can be obtained for the Cu-13.0Al-4.0Ni-0.2Sm alloy

Variation in reference crop evapotranspiration caused by the Ångström-Prescott coefficient: Locally calibrated versus the FAO recommended

Accurate estimation of the reference crop evapotranspiration (ET0) is investigated due to its critical role in affecting calculation of crop water use and efficiency in agricultural ecosystems. The main emphasis in this paper is to clarify the possible uncertainty in the estimation of ET0 associated with using un-calibrated Ångström-Prescott (A-P) coefficients. We first calibrated the coefficients using long-term data records from 34 sites in the Yellow River basin in China, and then applied these coefficients to estimate short wave irradiance (Rs) and ET0 at 16 sites to evaluate the difference in ET0 between the FAO recommended and the locally calibrated. We found that the direct use of the FAO recommended coefficients significantly affected the estimation of ET0 at most sites, which differed from -3% to 15% at daily scale and from -4% to 16% at monthly scale from the locally calibrated ones. These differences are comparable with or larger than those caused by some alternatives of the FAO recommended algorithms for net irradiance or vapor pressure, which further highlights the importance of using the locally calibrated coefficients. The degree of difference in ET0 showed a significant threshold relation with altitude and longitude in such a way that relatively small impact lies around 2233m and 98°E, and away from these, the effect begins to increase. Given the large overestimation in water use as a consequence of the significant overestimation in ET0 associated with the direct use of the FAO coefficients, especially in those high yield production areas with altitudeReference crop evapotranspiration Ångström-Prescott coefficients Penman-Monteith