预应力混凝土用30MnSi钢棒延迟断裂性能的改进.pdfVIP

ABSTRACT Several years since the introduction of high-speed wire rod mill from Morgan Stelmor Inc., Tianjin Steel Plant has been put much effort in the research and technological improvement of the production line. The researchers have acquired the key techniques, on the basis of which developed a series of new products, with varying specifications of Ф8.0-Ф13.0. However, problems of delayed fracture are occasionally reported in the products’ service life, causing inconvenience to the customers. To solve these problems, it is imperative that quality of products be improved through intensive investigation into the delayed fracture of 30MnSi hot-rolled wire rod. In the present study, the problem products were analyzed through industrial production and laboratory thermal simulation method s of, and the following conclusions were achieved. (1) In the smelting process, by use of high quality molten iron, strict control of raw material quality, and adoption of LF refining, the number of non-metallic inclusions could be effectively reduced and the content of elements in the steel could be precisely controlled. (2) Adopting whole process protection, low superheat, electromagnetic-stirred casting, combined with lower pulling rate, and control of liquid surface fluctuation, the surface quality of the slab, and the compositional segregation of the slab could be improved. (3) Strict inspection of the rolling blank, rational development, appropriate planning and execution of rolling process, and timely replacement of worn parts can effectively reduce surface defects of the rolling materials; controlling rolling tens