Manufacturing method for annealing drawn steel rods for finish machining

A steel bar and annealing technology, which is applied in the field of steel bar and its annealing and drawing process, can solve the problems of increased tool wear and sticking, and achieve good precision machining performance, low cost, and easy precision machining

Active Publication Date: 2019-08-30
JIANGYIN XINGCHENG SPECIAL STEEL WORKS CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Due to the low hardness and good toughness of the ferrite, it is easy to cause sticking to the tool and continuous chips, while the hardness of the bainite structure mixed in it is too high, which will aggravate the wear of the tool

Method used

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  • Manufacturing method for annealing drawn steel rods for finish machining
  • Manufacturing method for annealing drawn steel rods for finish machining
  • Manufacturing method for annealing drawn steel rods for finish machining

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] The material is 42CrMo steel. The chemical composition of the steel meets the smelting specifications of the industry standard. It belongs to the hypoeutectoid low-alloy steel. The chemical composition is not the design point of this application. Misunderstanding, the chemical composition is not disclosed in this embodiment, and those skilled in the art can refer to the industry standard for this steel grade:

[0030] 1) Steelmaking: Electric furnace + LF furnace + VD vacuum degassing + continuous casting are used to make steel. During the steelmaking process, the S content in the molten steel is adjusted, and the final content is stable at 0.030%. Higher S can make the steel bar In the subsequent rolling process, long strip-shaped sulfide inclusions are formed, which reduces toughness and improves chip breaking performance during machining.

[0031] 2) Rolling: The continuous casting billet is rolled into a 35mm-sized bar, and it is rolled off the line through a long c...

Embodiment 2

[0036] The material is 40Cr steel. The chemical composition of the steel meets the GB standard for the steel grade. It belongs to hypoeutectoid low alloy steel. The specific production steps are:

[0037] 1) Steelmaking: adopt electric furnace / converter + LF furnace + continuous casting to make steel, add sulfur to 0.035% in the molten steel, so that the steel bar will form long strips of sulfide inclusions in the subsequent rolling process, reduce toughness, and improve mechanical properties. Chip breaking performance during machining.

[0038] 2) Rolling: The continuous casting billet is rolled into a 24mma bar, and it is air-cooled to obtain a faster cooling rate (3°C / s) when it is off-line. The cooling rate passes through the bainite region of the CCT curve and ensures that The off-line temperature is lower than 550°C, and a metallographic structure dominated by bainite is obtained. At the same time, there is a small amount of ferrite in the structure. The volume fraction of...

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Abstract

The invention relates to an annealing drawn steel rod for finish machining; the steel rod selects raw materials of hypoeutectoid low-alloy steel; the steel rod adopts uniform (granular) bainite, and possibly contains fewer ferrites; carbide particles are uniformly distributed in a basal body; strip sulfide inclusions are distributed in the structure; and the hardness of steel is 160-250 HB. The steel rod with the bainite structure is generated after rolling of a blank; the annealed rod with controllable hardness is obtained through softening and annealing; the product with target hardness is drawn; the product shows excellent precise machining performances; and when a precise cutter is adopted to machine such shapes with higher chip removing requirements as small-diameter deep holes and annular blind holes, the life of the cutter is equivalent to that when isothermal annealed rods with the same hardness are machined, and is twice of that in a conventional annealing process.

Description

technical field [0001] The invention relates to a steel bar suitable for finishing and its annealing and drawing process. Background technique [0002] With the continuous development of mechanical cutting processing in the direction of automation, high speed, precision and complexity, parts manufacturers have higher and higher requirements for machinability of materials. The cutting performance of materials is affected by many factors. Taking steel materials as an example, Plastic elongated inclusions and flaky pearlite structure in steel It is beneficial to promote the formation of small and short curly chips during machining, which is easy to remove, reduces tool wear, reduces the roughness of the machined surface, and improves tool life; and choose the appropriate hardness The range is also very important. If the hardness is too high, it is easy to break chips but will increase tool wear. If the hardness is too low, it is easy to cut but will cause sticking and chip br...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D8/06C22C38/02C22C38/04C22C38/08C22C38/12C22C38/16C22C38/20C22C38/22C22C38/42C22C38/44C22C38/60
CPCC21D8/065C21D2211/002C21D2211/004C21D2211/005C22C38/02C22C38/04C22C38/08C22C38/12C22C38/16C22C38/20C22C38/22C22C38/42C22C38/44C22C38/60
Inventor 冀鸰胡绍鑫许晓红白云黄镇邵淑艳李芸孔祥伟
Owner JIANGYIN XINGCHENG SPECIAL STEEL WORKS CO LTD
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