Papers by Author: Zhen Hua Li

Abstract: Focusing on improving the galvanizability of the third generation automotive steel, the effect of surface oxides morphologies on the galvanizability was studied. The results show that the surface oxide types of sample steels by XPS analysis after annealing in different conditions are the same, only MnO and Cr₂O₃ were detected and no complex oxides exist on the surface. Morphologies of surface oxides can greatly influence the galvanizability of the third generation automotive steel, nodule-like oxides surface can contribute to better wettability and inhibition layer than vitreous film-like oxides surface. Galvanizing panels of nodule-like oxides surface steels only show pinhole-sized bare spots, while panels galvanized from vitreous film-like oxide surface steels reveal larger areas of bare spots and uncoated areas. Inhibition layer observed in galvanizing panels of nodule-like oxides surface steels are compact but not homogeneous, some inhibition layer grains are fine, and others are coarse. While the inhibition layer grains of panels galvanized from vitreous film-like oxide surface steels have a non-compact morphology with some particularly fine equiaxed crystals which developed deficiently.

Abstract: In order to get rid of health hazard of asbestos fiber, a new kind of non-asbestos fiber reinforce composite by beater-addition process, which is used for sealing and gasket, has been developed to replace traditional asbestos gasket materials. The mechanical properties of the new composite were tested, and the performance between it and asbestos sheet paper were contrasted. Results show that the density, cross direction tensile strength, machine direction tensile strength and ignition loss at temperature of 300°C of the new composite are 1.19g/cm3, 2.62MPa, 3.15MPa and 15.61% respectively, while the performances of asbestos paper produced under the same condition are 1.26g/cm3, 2.87MPa, 3.24MPa and 12.03% respectively. Excellent performance, low cost and simple manufacture process of the new composite make it is possible to substitute traditional asbestos paper and apply widely.

Abstract: A new nonlinear constructive model for description of temperature field of carbon steel axisymmetric body during the magnetic field quenching has been established based on thermo-magnetic coupling analysis. Using the model and finite element method, a numerical calculation program is developed with Microsoft FORTRAN 5.0, and cooling curves of center in a carbon steel sample of 30mm in diameter and 60mm in length during magnetic field quenching and common quenching are calculated and tested. Results showed that calculated cooling curves is accordant with corresponded tested cooling curves very well, and the calculated accuracy of temperature field during magnetic field quenching based on the new model is satisfactory.

Abstract: A bainite/martensite dual-phase cast steel was fabricated by a process of combination of alloying with Si and Mn elements and controlled cooling heat-treatment. Its microstructure was consisted of fine lower bainite with carbide particles precipitated homogeneously, martensite and a little residual austenite. Because of the good match of hardness and impact toughness, its impact wear performance was a little better than that of the isothermal quenching steel, and much better than that of high manganese steel such as Mn13.