ROLLED METAL AND TRANSFER OF ENHANCED STRENGTH FOR PRODUCTION OF NUTS OF THE CLASS OF STRENGTH 8 AND 9

摘要

The proposed solution relates to metallurgy and metal forming, more particularly - to the manufacture of rolled round smooth profile (wire rod) of the high strength low carbon steel for the production of fasteners, such as nuts, preferably hexagonal strength class 8 and 9. The proposed utility model solves the problem of obtaining rolled steel (wire rod) increased strength of ordinary steel grades for the production of class nuts 8 and 9, which prevents the heat treatment of the finished product and provides the reduction itself the cost of its production. The problem is solved in that the rolling is made in the form of a rod formed into a hank, low carbon steel containing 0.15 ... 0.35% carbon, 0.5 ... 1.6% Mn, the balance being iron and unavoidable impurities, the value of carbon equivalent _(eq C) not less than 0.23% determined by the formula: C _eq = C + Mn / 20 where: C, Mn - weight fraction of carbon and manganese in% and has a yield strength at least 360 N / mm ^2, tensile strength of at least 480 N / mm ^2, elongation (δ ₅₎ at least 28%, contraction ratio is not less than 60%. The process of preparation includes steelmaking, hot rolling and heat treatment. At this temperature the end of hot rolling to limit the range of from 950 to 1050 ° C, the heat treatment is carried out by means of rolling heat interrupted quenching to-average temperature of 660 ... 760 ° C, and the rolling is made as a rod with a diameter of 6.0 to 22.0 mm, formed into a hank whose weight can reach 5.0 tons.