| Hot rolled ribbed steel bars are widely used construction steels in building structures and other constructions. The output of rebar in China accounts for about 30% of long products. For a long time, rebar used in building structures is basically HRB355 in China, result in a waste of ore resource etc. On the other hand, the rebars with yield strength of more than 400MPa have been widely used in 70s in the 20th century as a main structural steel. With the continuous development of China's national economy, metallurgy, construction and other industries are speeding up the pace with international standards. Relative authorities in China have repeatedly requested to promote the use ofâ…¢andâ…£grade high-strength construction rebars. At present, the products in iron and steel plants are mainlyâ…¡grade rebar of 20MnSi series orâ…¢grade rebar with a small amount of microalloy elements, while the main products of foreign steel companies areâ…£grade rebar.Domestic enterprises have produced gradeâ…£rebar with the yield strength of more than 500MPa. The production route is to add Nb, V and other microalloy elements. The production costs are relatively high by this technical route because of higher price of addition element Nb and V, which makes the profits of gradeâ…£rebar is becoming less and less. Contrary, the price of addition Ti is lower than that of Nb and V, so it is important to develop new low-cost, high-strength gradeâ…£rebar with Ti-addition.In this paper, Ti microalloyed gradeâ…£rebar was developed in laboratory. The effects of compositions on microstructure and properties were studied and the optimum chemical compositions were decided. In addition, the inclusions in steel were investigated and the mechanism of precipitation strengthening in Ti microalloyed gradeâ…£rebar was analyzed. The refine and rolling technologies are also studied in the paper. |
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