Medium carbon steel on-line balling rolling tech.

A process, carbon steel technology, applied in the field of medium carbon steel online spheroidizing rolling process, to achieve the effect of saving energy, reducing environmental pollution and reducing manufacturing costs

Active Publication Date: 2007-07-18
MAANSHAN IRON & STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although the medium-carbon cold-heading steel wire can be directly softened online, it can avoid annealing the medium-carbon cold-heading steel wire to make 8.8 high-strength fasteners, and the annealing process before cold heading is omitted, but becau

Method used

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  • Medium carbon steel on-line balling rolling tech.

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specific Embodiment approach

[0020] Medium-carbon steel billets with a carbon content of 0.25% to 0.55% are used as raw materials, and conventional methods are used on plate, wire, and bar rolling mills to form rough rolling, intermediate rolling, pre-finishing rolling, and finishing rolling. The rolling temperature of rolling, intermediate rolling and pre-finishing rolling is 900-1050°C. The controlled-rolling-controlled-cooling low-temperature rolling process is adopted in the finishing rolling process, and the rolling temperature is controlled at 680-850°C. It is required that the low-temperature rolling has enough Large deformation, the deformation of the cross-section is 50% to 80% of the cumulative area reduction rate, and the deformation induces the dynamic phase transformation of ferrite, that is, the austenite precipitates ferrite during the deformation process, on the one hand, it increases the ferrite in the structure. Ratio, refine ferrite grains, on the other hand, increase the carbon concentr...

Embodiment 1

[0025] Use any medium-carbon steel billet with a carbon content of 0.25% to 0.55%, the rolling temperature for rough rolling, intermediate rolling, and pre-finishing rolling is 950°C, the metallographic structure of the rolled piece is austenite, and cool to 700°C , rolling deformation at 50% area reduction rate, deformation rate 20 / s, and then cooling to 680°C at 5°C / s, after isothermal process or slow cooling process, the metallographic structure of the rolled piece after natural cooling to room temperature is ferrite Body + carbide spheroidized pearlite.

[0026] The isothermal process is cooling to 680°C and the holding time is 600 seconds; the slow cooling process is cooling to 680°C and then slow cooling at a cooling rate of 0.2°C / s.

Embodiment 2

[0028] Use any medium-carbon steel billet with a carbon content of 0.25% to 0.55%. The rolling temperature for rough rolling, intermediate rolling, and pre-finishing rolling is 950°C. The metallographic structure of the rolled piece is austenite, and it is cooled to 750°C. , rolling deformation at 70% area reduction rate, deformation rate 20 / s, and then cooling to 680°C at 8°C / s, after isothermal process or slow cooling process, the metallographic structure of the rolled piece after natural cooling to room temperature is ferrite Body + carbide spheroidized pearlite.

[0029] The isothermal process is cooling to 680°C and the holding time is 900 seconds; the slow cooling process is cooling to 680°C and then slow cooling at a cooling rate of 0.1°C / s.

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Abstract

The present invention discloses on-line medium carbon steel nodularizing and rolling process. The process includes low temperature finish rolling at 680-850 deg.c and accumulated cross section deformation of 50 %-80 %, controlled cooling after rolling at 3-15 deg.c/s to 660-720 deg.c, isothermal course, and naturally cooling to room temperature. The said technological scheme results in metallographic structure of the rolled piece with high ferrite component, less pearlite component, small and dispersed pearlite and granular cementite, lowered strength and hardness, raised plasticity and excellent cold machining performance.

Description

technical field [0001] The invention relates to a metallurgical process, more specifically, the invention relates to an online spheroidizing rolling process of medium carbon steel. Background technique [0002] Special steel occupies a very important position in the whole steel product and is an important raw material for cold processing. Special steel produced according to the traditional metallurgical production process, such as cold heading steel, bearing steel, gear steel, spring steel, alloy structural steel and carbon structural steel, etc., in order to have good cold working performance, the material is required to have low deformation resistance And excellent plasticity, therefore, the carbide (ie cementite) in the steel microstructure is required to be spherical. For this reason, spheroidizing annealing is generally performed before cold working. This annealing treatment often takes a long period, consumes a lot of energy and resources, and pollutes the environment...

Claims

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Application Information

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IPC IPC(8): C21D8/00C21D11/00B21B37/74B21B37/56B21B37/46
Inventor 于同仁惠卫军胡孝三张步海孙维华刚苏世怀
Owner MAANSHAN IRON & STEEL CO LTD
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