Study And Development Of The Multi-wire And Large Diameter Low Relaxation PC Steel Strand

Along with the rapid enhancement of pre-stressing technology, the scale of pre-stressing construction is greater. As a kind of skeleton material, PC steel strand is expected the performance becomes more and more high, 1×7—Φ15.24 mm-1860MPa low relaxation PC steel strand is now in widespread use is not able to satisfy the need of the high and advanced pre-stressed construction day by day. In order to make up for the strength insufficiency of the thin diameter PC steel strand, it has the realistic feasibility that enhances the strength of pre-stressing products through the increase of PC steel strand diameter using the available raw material and technology, the development of multi-silk and large diameter low relaxation PC steel strand becomes the most new development direction of the pre-stressing technology. The relation between the performance of 1×7-Φ15.24mm-1860MPa low relaxation PC strand and the raw material quality or the steel wire drawing technology was studied in this article, then the production technology of 1X19 large diameter low relaxation PC steel strand was designed.The studied results indicates that, the sorbite content, abnormal microstructure in the central and the larger inclusion of wire rod have remarkable effect, and become the primary factor of affecting the mechanical performance of steel wire and strand during steel wire drawing and stranding; When the average pass draught is about 18%, the first pass draught is smaller, the second pass draught is bigger, and the later pass draught reduces gradually, the effect of steel wire drawing is good, and...