Preparation method of high-purity low-alloy ultrahigh-strength steel bar
By employing a synergistic process of LF refining, RH cyclic degassing, and vacuum consumable smelting, combined with optimization of parameters across the entire process chain, the problems of high equipment investment and difficulty in achieving both high purity in the preparation of 300M steel have been solved. This has enabled the efficient preparation of high-strength steel bars, meeting the stringent requirements of high-end fields such as aerospace.
Patent Information
- Application Number
- CN202610470420.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-04-10
- Publication Date
- 2026-06-23
AI Technical Summary
Existing processes for preparing low-alloy ultra-high-strength steel (300M steel) suffer from problems such as large equipment investment, long production cycles, high costs, and difficulty in adapting to large-scale industrial production. In single-vacuum processes, inclusions are prone to secondary adsorption of gas, making simultaneous removal impossible. The RH vacuum degassing process does not take into account the alloy characteristics of 300M steel, resulting in insufficient floating force for inclusions. Each process step is operated independently with mismatched parameters, making it difficult to achieve both steel purity and mechanical properties.
The dual synergistic smelting process of LF refining + RH circulating degassing + vacuum consumable remelting is adopted. Combined with precise optimization of the parameters of the entire process chain and multi-pass forging-heat treatment, the synergistic control of gas removal and inclusion flotation is achieved by designing the steel circulation parameters of RH degassing and the convection parameters of the molten pool of vacuum consumable remelting, thereby refining the grains and optimizing the microstructure.
A high-purity 300M steel bar with excellent strength and toughness was prepared, with a tensile strength of 1930-2070MPa and a fracture toughness of ≥55MPa·m0.5. This breakthrough overcomes the technical bottleneck of traditional processes that make it difficult to balance purity and mechanical properties, reduces production costs, adapts to large-scale production, and improves service safety.