High-Nitrogen Steel Wire for Nonmagnetic Power Line Core
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Solution Overview
Problem
Current methods for manufacturing high-nitrogen steel wire, such as PESR and Plasma Arc Remelting, are limited in achieving high nitrogen concentration and tensile strength, leading to increased power losses and instability in overhead power lines due to magnetic permeability and core losses.
Innovation Solution
A pressurized induction furnace process is used to dissolve nitrogen in alloy components with specific compositions (25-35 wt% Mn, 25-35 wt% Cr, 10-20 wt% Ni, 0.5-1.0 wt% C, and 20-35 wt% Fe) to achieve a nitrogen concentration of 12,000 ppm or higher, resulting in high-strength, non-magnetic steel wire with reduced magnetic permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional manufacturing methods (PESR or Plasma Arc Remelting) are used to increase nitrogen concentration, then nitrogen content can be increased to some extent, but the tensile strength and magnetic permeability cannot be optimized sufficiently
Solution Approach 1:
The patent changes the manufacturing parameters by using a pressurized vacuum induction melting furnace with nitrogen pressure control (0.1-10 atm). By controlling the nitrogen pressure during melting and the cooling rate (10-1000°C/s), the patent achieves simultaneous optimization of nitrogen concentration (1000-5000 ppm), tensile strength (≥1200 MPa), and magnetic permeability (≤4000), resolving the contradiction between nitrogen content and mechanical properties that plagues conventional methods
Solution Approach 2:
The pressurized vacuum induction melting furnace performs multiple functions simultaneously: it creates a vacuum environment to prevent oxidation, controls nitrogen pressure to dissolve nitrogen into the steel, and provides controlled cooling. This multi-functional approach allows single-step production of high-nitrogen steel with optimized properties, whereas conventional methods require separate processing steps that cannot achieve the same level of optimization
2Strength
If high-carbon steel wire with high tensile strength is used as core, then the supporting strength is sufficient, but the magnetic permeability is high (4000 or higher) causing ferromagnetic properties and increased power loss
Solution Approach 1:
The patent changes the chemical composition parameters by adding nitrogen (1000-5000 ppm) to high-carbon steel (0.5-1.0% C). This compositional change transforms the magnetic properties by forming austenite structure, reducing magnetic permeability to ≤4000 while maintaining tensile strength ≥1200 MPa, thus resolving the contradiction between strength and power loss
Solution Approach 2:
The patent creates a composite material system by combining high-carbon steel with nitrogen to form high-nitrogen steel. This composite approach leverages the strength-providing capability of carbon while nitrogen contributes to austenite formation and magnetic property modification, achieving both high strength and reduced ferromagnetism simultaneously
3Loss of energy
If the cross-sectional area of the core is increased to reduce magnetic permeability effects, then non-magnetic properties improve, but the overall wire thickness increases and aluminum conductor capacity is reduced
Solution Approach 1:
The patent changes the magnetic property parameters by introducing nitrogen to achieve magnetic permeability ≤4000. This parameter change allows the core to maintain adequate size without excessive magnetic losses, as the nitrogen-induced austenite structure inherently reduces ferromagnetic effects, resolving the trade-off between core size and magnetic loss
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The process enables the production of high-nitrogen steel wire with enhanced mechanical properties and non-magnetic properties, reducing core losses and increasing power transmission capacity by allowing a larger cross-sectional area for aluminum conductors without changing the wire thickness, thus improving efficiency and stability.
Implementation Method 1
injecting nitrogen gas to reach a partial pressure of 2 atmospheres in a nitrogen gas environment after having first adjusted the pressure to 6×10^-5 torr for a second vacuum and melting the alloy components constituting the nitrogen steel
Implementation Method 2
pressurized induction furnace process is used to dissolve nitrogen in alloy components
Data Source
AI summary
Disclosed are a method for manufacturing a nonmagnetic high-nitrogen steel wire, and an overhead power line adopting the high-nitrogen steel wire as the core thereof. According to one embodiment, the method for manufacturing high-nitrogen steel wire comprises the steps of injecting argon (Ar) gas to reach atmospheric pressure after having first adjusted the pressure to 6×10−5 torr for an initial vacuum using a pressurized vacuum induction melting (VIM) furnace; and injecting nitrogen gas to reach a pressure of 2 atmospheres after having first adjusted the pressure to 6×10−5 torr for a second vacuum, and melting a nitrogen steel alloy consisting of 25 to 35 wt % of Mn, 25 to 35 wt % of Cr, 10 to 20 wt % of Ni, 0.5 to 1.0 wt % of C, and 20 to 35 wt % of Fe, which are alloy elements constituting nitrogen steel. The high-nitrogen steel wire manufactured in this manner has a nitrogen content ratio higher than 12,000 ppm, excellent mechanical strength, and nonmagnetic characteristics. By using this high-nitrogen steel wire, an overhead aluminum power line with a nonmagnetic steel core for reducing power loss and increasing power transmission capacity can be provided.