A method for refining and controlling nitrogen of a swaged connecting rod steel

By using the LF+RH dual-synergistic nitrogen control system and nitrogen gradient nitrogen stabilization technology, the problem of precise control of nitrogen content under ultra-low oxygen conditions has been solved, enabling low-cost, high-yield, and high-cleanliness production of steel for fracture-resistant connecting rods.

CN122344643APending Publication Date: 2026-07-07HEBEI VOCATIONAL & TECH UNIV OF SCI & TECH +2
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Patent Information

Authority / Receiving Office
CN Β· China
Patent Type
Applications(China)
Current Assignee / Owner
HEBEI VOCATIONAL & TECH UNIV OF SCI & TECH
Filing Date
2026-06-09
Publication Date
2026-07-07

AI Technical Summary

Technical Problem

Existing processes are difficult to achieve precise control of nitrogen content within a narrow window under ultra-low oxygen clean conditions, resulting in high costs, low yield, and difficulty in ensuring component uniformity. In particular, the process is severely fragmented in the LFRH duplex refining process, with repeated fluctuations in nitrogen addition and removal, making it impossible to stably lock onto the target window.

Method used

The LF+RH dual-synergistic nitrogen control system is adopted. By precisely pre-increasing nitrogen during the LF refining process and stabilizing nitrogen with nitrogen gradient under RH vacuum conditions, combined with four-stage stepped flow regulation of the RH molten steel flow field, the nitrogen content under ultra-low oxygen conditions can be precisely controlled.

Benefits of technology

It has achieved stable control of nitrogen content within the range of 160-200 ppm under ultra-low oxygen conditions, which has reduced production costs, improved yield and composition uniformity, and ensured process stability and high cleanliness.

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Abstract

The present application belongs to the technical field of metallurgical refining, and specifically discloses a refining nitrogen control method for expansion fracture connecting rod steel. The refining nitrogen control method provided by the present application comprises the following steps: at 1550-1580 DEG C, performing differential flow nitrogen blowing treatment on molten steel to obtain first-stage LF refining molten steel; performing nitrogen increasing treatment on the molten steel after alloying at a rate of 3-7 ppm / min to obtain LF refining molten steel; and performing nitrogen blowing treatment on the LF refining molten steel in a four-stage stepped increasing flow in turn at 1640-1645 DEG C and a vacuum degree of 70-80 Pa to obtain RH refining expansion fracture connecting rod molten steel. The expansion fracture connecting rod molten steel prepared by the method has a total oxygen content of ≀3.5 ppm and a nitrogen content of 160-200 ppm, and the purpose of low-cost production of high-quality nitrogen-containing steel is achieved.
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