Spheroidizing annealing technology of high-tenacity fastener wire rod

Abstract

The invention discloses a spheroidizing annealing technology of a high-tenacity fastener wire rod. The spheroidizing annealing technology comprises the following steps: placing a fastener wire rod into a thermal treatment furnace, introducing a protective gas into the thermal treatment furnace, raising the temperature in the furnace to 720-740DEG C, and performing heat preservation for 1-3h; carrying out first-stage cooling: cooling the temperature in the furnace to 680-700DEG C at the speed of 10DEG C / h, and performing heat preservation for 2-4h; carrying out second-stage cooling: further reducing the temperature in the furnace to 630-650DEG C at the speed of 20DEG C / h; and carrying out third-stage cooling: naturally cooling the fastener wire rod to normal temperature. The fastener wire rod treated by adopting the technological method is uniform in metallographic structure, high in tenacity, high in ductility, low in hardness and suitable for subsequent high-difficulty repeated plastic machining forming, and the forming cracking rate of the product is low.

Description

Technical field: [0001] The invention relates to an annealing process for metal materials, in particular to a spheroidizing annealing process for high-toughness fastener wires. Background technique: [0002] Spheroidizing annealing is one of the basic ways to improve the structure and properties of steel. The main purpose of spheroidizing annealing is to spheroidize carbides in the microstructure of steel materials, reduce the hardness of materials, improve the plasticity of materials, and reduce the deformation resistance of materials. , making the material easy to plastic processing. Fasteners are the general term for a class of mechanical parts used when two or more parts (or components) are fastened and connected into a whole. In order to obtain ideal performance and organization in the production of fastener wires, the key is Select the appropriate spheroidizing annealing process. [0003] At present, in industrial production, the two-phase zone spheroidizing anneali...

AI Technical Summary

Problems solved by technology

[0003] At present, in the industrial production, the two-phase zone spheroidizing annealing process is mostly used to obtain the spheroidized carbide structure. The beneficial effect of undissolved carbide in homogeneous austenite or the non-self-nucleation of high-concentration carbon segregation in austenite accelerates spheroidization. However, in fact, when the temperature is above the A1 temperature, the carbide is completely dissolved within 0.5h , If the pearlite is very fine, the dissolution will be more rapid. Therefore, according to the existing process, if it is heated above the temperature of A1 and then slowly cooled to below A1, the fine pearlite structure will often be slowly cooled or kept warm. The result is that it is not conducive to the spheroidization of carbides, and it is difficult to obtain an ideal pearlite spheroidization structure. When producing fastener wires, the metallographic structure is uneven and the hardness is high. Poor toughness, a large number of fastener wires have cracks after cold forming, the light ones need to cut off the cracked parts, and the severe ones will directly lead to the scrapping of the fastener wires produced, seriously affecting the quality and yield of fastener wires