High-strength steel tension rod and thermal treatment method thereof

Abstract

The invention belongs to the field of metallurgy, and in particular relates to a high-strength steel pull rod and a method for producing the same through heat treatment. The high-strength steel pull rod comprises the following chemical components in weight percent: 0.25 to 0.50 percent of C, 0.30 to 1.8 percent of Si, 0.50 to1.8 percent of Mn, less than or equal to 0.03 percent of P and S; 0.15 to 0.55 percent of Mo, 0.25 to 1.2 percent of Cr, and one or more of V, Ti and B. The mechanical properties are as follows: the yield strength is between 650 and 1,080 N / mm<2>, the tensile strength is between 850 and 1,230 N / mm<2>, the percentage elongation after fracture is more than or equal to between 9 and 15 percent, and the relaxation rate is less than or equal to 4.0 percent or 2.5 percent. The microstructure is a tempered martensite structure. The high-strength steel pull rod adopts induction heat treatment under tensile stress state, the quenching heating temperature is between 850 and 1,050 DEG C and is then cooled to below 250 DEG C, and the tempering heating temperature is between 400 and 700 DEG C; besides, the microstructure of the finished steel pull rod is the superfine tempered martensite structure basically.

Description

technical field [0001] The invention belongs to the field of metallurgy, and in particular relates to a high-strength steel tie rod and a heat treatment method thereof. Background technique [0002] As an important component in the construction of long-span buildings, docks, docks and bridge structures, steel tie rods are mainly used in prestressed parts and environments in engineering project structures. The current steel tie rod standard in my country is GB / T20934--2007, which is suitable for steel tie rods used in civil engineering structures. The mechanical properties of the rod body are specified as follows: [0003] [0004] Yield strength 650-1080N / mm is not included in the above standard 2 products, and the relaxation performance is not included in the requirements for steel rod inspection. The relaxation rate (Vs) is the stress drop value per unit time, that is, the slope of the stress relaxation curve at a given moment, However, steel tie rods are mainly used...

AI Technical Summary

Problems solved by technology

Using this traditional heat treatment process, the operation is cumbersome, the energy consumption is large, and the heating time is long. It takes several hours to complete the heating from room temperature to the quenching heating temperature. The surface of the steel tie rod is seriously decarburized and the microstructure is coarse.

There are disadvantages of uneven heating, uneven cooling, large fluctuations in performance and quality between batches and roots, and it is easy to cause bending and deformation of steel tie rods. The flatness of the product exceeds the standard requirements, and the relaxation rate is high. , since my country's national standard does not specify the relaxation rate, this technical problem has not been effectively resolved

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