The anisotropy and it's evolution during ageing treatment for Al-Li alloy 1420 cold-rolling sheet were investigated by means of tensile test and fractograph observation.
Though polyurethane leather with its characteristic advantages of resistance to oil, abrasion, cold, flexion, and good mechanical strength, it has disadvantage of easily ageing.
聚氨酯合成革有耐油、耐磨、耐寒、耐屈曲、机械强度好等优点，但也容易发生老化。
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The strain ageing of cold-rolling ribbed bar leads to high strength and drop of elongation, so this seriously affects the quality of concrete component and regular production of the bar.