Method for softening and rolling cold forging steel

Abstract

The invention discloses a method for softening and rolling a cold forging steel. The main process flow comprises the steps of heating, rolling, performing finish rolling, spinning, performing Sitaimoer roller controlled cooling, collecting, transporting, bundling, performing coil discharging, keeping the temperature in a temperature controlled chamber and performing stack cooling, wherein after collecting is finished, the cold forging steel coil is put to a P-F transportation line and the steel coil is rapidly transferred to a bander along a straight line rail; after coil discharging is finished, the steel coil is put to the temperature controlled chamber and slowly operates in the temperature controlled chamber until the temperature is 400-600 DEG C when the steel coil reaches the outlet; and finally stack cooling is performed to achieve room temperature. By adopting the method, the problems of low plasticity of the steel material and easy cracking of the cold forging steel due to integrated inner stress of the rolled cold forging steel are solved, the deep processing capability of the steel material is increased and the non-annealing of the cold forging steel is realized.

Description

technical field [0001] The invention belongs to the technical field of iron and steel pressure processing, and in particular relates to a softening and rolling processing method for producing light round wire rods and cold heading steel bars by a high-speed wire rolling mill in the iron and steel industry. Background technique [0002] At present, the demand for steel for cold heading and cold extrusion in China is gradually increasing, and the annual demand has reached more than 10 million tons. The proportion of cold heading steel fasteners of grade 8.8 and above has increased year by year, and has reached 40% of the total fasteners. 60% to 70%. The raw materials for the production of high-grade fasteners of grade 8.8 and above are generally high-strength steels such as medium carbon or medium carbon alloy steel. The material itself has high strength and hardness, and its plasticity index is relatively poor. Fastener processing enterprises need to perform spheroidizing an...

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Problems solved by technology

The advantage of the first type of method is that the effect of softening steel is obvious, but the requirements for process technology and production equipment are relatively high, the rolling is difficult, and the consumption of spare parts is high, especially the possibility of smooth production on ordinary high-speed rolling mills is small. ; The second type of method can reduce the strength of the steel by reducing the alloy elements in the steel and rolling with ordinary methods, but the problem is that it may affect the strength, hardenability, hardenability, etc. of the fasteners; the disadvantages of the third type of method The reason is that the steel needs to be kept warm and slowly cooled on the Stelmo roller table cooling line for a long time, which is almost impossible for a single-line rolling mill, and it is very difficult to achieve normal economic production even for a four-line rolling mill.

[0006] To sum up, at present, the more effective rolling method for softening cold heading steel is based on the theory of "deformation-induced phase transformation", which enables the rolled piece to be rolled under the condition of "low temperature and large reduction" to achieve softening, but this process It is very difficult to realize and economically produce cold heading steel in batches on ordinary high-speed rolling mills, and the popularization and application are limited

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