INFLUENCE OF DEGREE OF THICKNESS REDUCTION RATIO ON DEVELOPMENT OF STRUCTURE IN THE STEEL 1 . 5710
Intensity of structural changes during forging is usually determined in dependence on the forging ratio. Forging ratio at elongation is most often calculated with use of simple relations, which are based on the change of cross-section of the forged pieces. The intensity of structure development is influenced not only by the simple change of cross-sections, but also by relative length of the stroke, magnitude of deformation in individual passes, manner of edging, temperature, friction and shape of anvils. The paper gives an analysis of influence of the relative length of the stroke on the forging ratio.
STRAIN IN THE UPSETTING PROCESS
In the paper strain distribution in materials commonly referred to as soft materials (electrolytic copper 99,9 % Cu, annealed) and hard ones (steel 20, containing 0,2 % C) produced during hot upsetting process. Numerical calculations were performed with a use of commercial software QForm2D/3D. Significance of the influence of friction forces in the head surface on the free surface profile and distor-tion of rectangular coordination grid of deformations, as well as, effective strain distribution, in various stages of the process was investigated. The results indicate changes in nonuniformity of strain in obtained forgings.
Experimental investigation of the geotechnical properties and microstructure of lime-stabilized saline soils under freeze-thaw cycling
Abstract The Song-Nen Plain in northeastern China holds one of the three largest expanses of soda saline-alkali soil in the world. Due to its disadvantageous geotechnical properties, the saline soil in this area is unable to meet the needs of construction projects. This study evaluates the stabilizing effect of adding lime to such soils. Specifically, it investigates how the physicochemical and mechanical properties and microstructure of soda saline-alkali soil are altered by lime and how these changes are affected by both freeze-thaw cycling and the duration of curing. The results reveal that adding lime to saline soil transforms clay particles into sand and silt particles and causes the pore size distribution (PSD) to become bimodal, with small-pore and macropore populations. An increase in lime content leads to an increase in the unconfined compressive strength (UCS) but a gradual decrease in both the cation exchange capacity (CEC) and plastic index. Freeze-thaw cycles break up coarse particles and aggregate finer particles, increasing the diameter of macropores and decreasing the USC; however, the effect on specimens with >9% lime is negligible. It is further shown that the geotechnical properties of the soil change immediately after the addition of lime, indicating that the cation exchange reaction takes place very quickly. Furthermore, the pozzolanic reaction leads to an increase in the percentage of sand-sized particles and a decrease in porosity after 28 days of curing. Overall, these results indicate that it is feasible to use lime to improve the engineering properties of soda saline-alkali soil in this area.