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我国1987从西德和意大利引进了冷轧螺纹钢筋成套设备。某厂于1988年生产出直径5～6mm冷轧螺纹钢筋。这种钢筋是由低碳盘圆(3号钢)经冷轧而成,表成带螺纹,强度高,塑性好。它既有冷拔低碳钢丝的特性,又有变形截面钢筋特有的与砼粘结性好的优点。于1988年通过市级技术鉴定。冷轧螺纹钢筋抗拉强度为700～800MPa,是Ⅰ级钢的二倍以上,比冷拔钢丝高20％;延伸率为3.5％;可反复弯曲五次以上;握裹力是光面钢筋的三倍以上。由于变形截面可减少钢筋在砼中滑移,推迟了裂缝的出现,抑制了裂缝的开展,提高了构件
In 1987, our country introduced cold rolling screw rebar complete sets of equipment from West Germany and Italy. A factory in 1988 produced a diameter of 5 ~ 6mm cold-rolled rebar. This rebar is made of a low-carbon disk (steel No. 3) that has been cold-rolled to form a thread with high strength and good plasticity. It not only has the characteristics of cold-drawn low-carbon steel wire, but also has the advantages of good adhesion to the crucible of the deformed section steel. In 1988 passed the municipal technical appraisal. Cold rolled steel bar tensile strength of 700 ~ 800MPa, is more than twice the level I steel, 20% higher than the cold drawn steel wire; elongation rate of 3.5%; can be bent more than five times; grip strength is smooth steel bar More than three times. Because the deformed section can reduce the slippage of the steel bar in the concrete, it delays the appearance of cracks, inhibits the development of cracks, and improves the components.