高强度低松弛管桩钢筋的发展及质量现状

Evolution and Quality Situation of High Strength Low Relaxation Rod for Pipe Pile

介绍高强度低松弛凹螺纹预应力管桩钢筋的发展及生产和质量现状 ,指出我国管桩钢筋存在的质量问题 ,并进行了分析 ,认为钢筋镦头开裂与原材料的质量有关 ,观察到断口组织晶粒粗大 ,有时有杂质和微孔 ;钢筋的滞后断裂、抗拉强度波动大 ,延伸率不稳定 ,表面质量不好是管桩钢筋生产上的原因。要保证管桩钢筋有好的质量 ,应保证合适的原料化学成分 [w(C) =0 2 5 %～ 0 45 % ,w(Si) =1 0 %～ 2 0 % ,w(Mn)≤ 1 0 % ,w(Si) /w(Mn) =1 2 0± 0 30 ],合适的回火温度 (35 0～ 5 0 0℃ ) ,合适的应变值 (≥ 0 8% ) ,好的挺直度 (≤ 3mm/m)

To introduce the evolution and production and quality situation of high strength low relaxation concave thread prestressed rod for pipe pile The quality problems existing in rod for pipe pile produced in China are pointed out It is considered through analyzing that the rod cracking when upset is related to the quality of raw materials The coarse grain and impurity and micro holes in fracture microstructure are observed It is due to production process that rod exists hysteresis fracture,tensile strength has strong fluctuation,percentage elongation is not stable and surface quality is bad In order to easure good quality of rod for pipe pile,it must be ensured that the chemical composition of raw material is suitable[ w (C)=0 25%～0 45%, w (Si)=1 0%～2 0%, w (Mn)≤1 0%, w (Si)/ w (Mn)=1 20±0 30],temper temperature issuitable(350～500?℃),strain value is suitable(≥0 8%),straight and upright degree is good (≤3?mm/m) and etc