Spheroidizing annealing method for medium-and-low-carbon alloy cold forging steel

A low-carbon alloy and spheroidizing annealing technology, which is applied in the field of deep processing of wire rods, can solve the problems of poor diffusion effect and achieve the effect of simple process, good effect and no impact on cost

Inactive Publication Date: 2016-10-12
XINGTAI IRON & STEEL
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

This patent is also heated below Ac1, for alloy steel, the diffusion effect is not good

Method used

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  • Spheroidizing annealing method for medium-and-low-carbon alloy cold forging steel
  • Spheroidizing annealing method for medium-and-low-carbon alloy cold forging steel
  • Spheroidizing annealing method for medium-and-low-carbon alloy cold forging steel

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Experimental program
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Effect test

Embodiment 1

[0029] Embodiment 1: Taking 20Cr cold heading steel as an example, the specific process of the spheroidizing annealing method of low carbon alloy cold heading steel is as follows.

[0030] The Ac1 temperature of 20Cr cold heading steel is 766°C. Since the carbon content of this steel is not high, it can be drawn directly, with a deformation of 25%. Taking a wire rod with a diameter of Φ16mm as an example, after pickling and phosphating, it can be drawn to Φ13.8mm at one time. After that, the spheroidizing annealing process is carried out. First, the temperature is raised to 790°C for 1.5h, and then the temperature is lowered to 740°C at 15°C / h for 1.5h; after 3 cycles, it is slowly cooled to 550°C, and then air-cooled to room temperature.

[0031] Through the 20Cr wire rod of present embodiment spheroidization process, by figure 1 It can be seen that its spheroidized structure level is greater than 5, which can meet the requirements of cold heading with large deformation.

Embodiment 2

[0032] Example 2: Taking 30CrMnSi cold heading steel as an example, the specific process of the spheroidizing annealing method of low carbon alloy cold heading steel is as follows.

[0033] The Ac1 temperature of 30CrMnSi cold heading steel is 760°C. There are many types of steel alloys, and softening annealing is required before drawing. The annealing temperature is 740 ° C and the temperature is kept for 5 hours. After softening and annealing, pickling and phosphating are carried out, and then 40% cold drawing deformation is carried out; taking the Ф20mm specification as an example, it is drawn twice to Ф16.1mm. Keep at 780°C for 2 hours, then cool at 18°C / h to 730°C and hold for 1.5 hours. After 3 cycles, the furnace is cooled to 500°C and then air-cooled to room temperature.

[0034] The 30CrMnSi wire rod processed by the spheroidization of the present embodiment is made of figure 2 It can be seen that its spheroidized structure level is 6, which can meet the requiremen...

Embodiment 3

[0035] Example 3: Taking 30CrMo cold heading steel as an example, the specific process of the spheroidizing annealing method of low carbon alloy cold heading steel is as follows.

[0036]The Ac1 temperature of 30CrMo cold heading steel is 757°C. There are many types of steel alloys, and softening annealing is required before drawing. The annealing temperature is 730 ° C and the temperature is kept for 4 hours. After softening and annealing, pickling and phosphating are carried out, and then 30% cold drawing deformation is carried out; taking the Ф14mm specification as an example, it is drawn to Ф11.7mm at one time. Insulate at 785°C for 2.5h, then cool at 10°C / h to 730°C and hold for 1.0h. After 3 cycles, the furnace is cooled to 500°C and then air-cooled to room temperature.

[0037] Through the 30CrMo wire rod of present embodiment spheroidization process, by image 3 It can be seen that its spheroidized structure level is 6, which can meet the requirements of cold heading...

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Abstract

The invention discloses a spheroidizing annealing method for medium-and-low-carbon alloy cold forging steel. The method technology includes the steps that firstly, cold drawing deforming is conducted, wherein cold drawing deforming with the deformation ranging from 25% to 40% is conducted on an alloy steel wire of the medium-and-low-carbon alloy cold forging steel; secondly, spheroidizing is conducted, wherein the temperature of the alloy steel wire obtained after cold drawing deforming is increased to Ac1+20 DEG C to Ac1+30 DEG C, heat insulation is conducted, then the temperature is reduced to Ac1-20 DEG C to Ac1-30 DEG C, and heat insulation is conducted; and thirdly, discharging is conducted, wherein the alloy steel wire obtained after spheroidizing is slowly cooled and discharged. By means of the method, an adjusting drawing and spheroidizing technology is combined with a spheroidizing annealing technology with the single-pass deformation larger than 25% so that the spheroidizing effect of medium-and-low-carbon alloy cold forging steel can reach the fifth level or higher, and the spheroidizing structure is good and cannot crack in the subsequent cold forging process; and the beneficial effects that the technology is simple and effects are good are achieved. When multiple times of repeated spheroidizing annealing periods are adopted in the method, although several times of cooling is added, the total annealing time is not prolonged, the cost is not affected, and the beneficial effects that effects are good and cost is low are achieved.

Description

technical field [0001] The invention belongs to the field of deep processing of wire rods, in particular to a spheroidizing annealing method for low-carbon alloy cold heading steel. Background technique [0002] Cold heading steel wire rod or wire rod often needs spheroidizing treatment in the deep processing of wire rod. The general purpose of cold heading steel is to make standard parts such as bolts and nuts and other special-shaped parts, which require good cold heading performance; spherical pearlite structure is considered to be the most suitable structure for cold heading. General cold heading steel is hot-rolled into wire rod, which is usually ferrite plus pearlite structure, which needs deep processing (spheroidization treatment) to transform the structure into spherical pearlite structure; in order to facilitate spheroidization, in Before the spheroidizing treatment, a certain amount of drawing is carried out to elongate and break the pearlite structure. [0003]...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D1/32C21D9/52C21D8/06
CPCC21D1/32C21D8/06C21D9/525
Inventor 苑希现王宁涛田新中张治广陈继林王利军孔令波翟进坡刘超冯忠贤张鹏黄翠环
Owner XINGTAI IRON & STEEL
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