High-Carbon Steel Wire Rod Composition Without Isothermal Treatment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing high-carbon steel wire rods struggle to simultaneously achieve high strength and high plastic toughness while maintaining cost-effectiveness, often requiring offline isothermal treatment or excessive alloying elements, leading to high production costs and difficulty in quality control.
Innovation Solution
A high-strength economical high-carbon steel wire rod composition comprising specific mass percentages of C, Si, Mn, Cr, V, Al, O, and N, with a balanced (V+Al)/(C+100N) ratio, and a manufacturing process involving smelting, billet casting, controlled rolling, and air cooling to achieve a refined sorbite structure, without isothermal treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If offline isothermal treatment is applied to high-carbon wire rods to achieve high strength, then tensile strength is improved, but production cost increases and manufacturing complexity increases
Solution Approach 1:
The patent extracts and eliminates the offline isothermal treatment step from the manufacturing process. By designing a specific chemical composition (C: 0.84-0.89%, Si: 0.60-1.00%, Mn: 0.30-0.80%, Cr: 0.25-0.50%, V: 0.02-0.06%, Al: 0.02-0.05%) and applying controlled rolling followed by air cooling, the wire rod directly forms a refined sorbite structure during production, achieving high strength without the need for subsequent isothermal treatment, thereby reducing production cost and manufacturing complexity
Solution Approach 2:
The patent changes the chemical composition parameters of the wire rod by precisely controlling the content ranges of C, Si, Mn, Cr, V, and Al elements. This parameter optimization enables the material to form a refined sorbite structure during controlled rolling and air cooling, achieving high strength (≥1320 MPa) and good plasticity simultaneously, thus eliminating the need for expensive offline isothermal treatment while maintaining or improving strength properties
2Strength
If alloying elements are increased to improve strength, then tensile strength is improved, but production cost increases
Solution Approach 1:
The patent optimizes the chemical composition parameters by precisely controlling the content ranges of alloying elements (C: 0.84-0.89%, Si: 0.60-1.00%, Mn: 0.30-0.80%, Cr: 0.25-0.50%, V: 0.02-0.06%, Al: 0.02-0.05%). This balanced composition design achieves high strength through synergistic effects of multiple elements rather than excessive addition of single elements, controlling production cost while meeting strength requirements
Solution Approach 2:
The patent creates a composite strengthening effect by combining multiple alloying elements (C, Si, Mn, Cr, V, Al) in specific proportions. Each element contributes differently: C provides high strength foundation, Si enhances strength and controls inclusions, Mn improves hardenability, Cr refines grain structure, V and Al form fine precipitates. This composite approach achieves superior strength-cost ratio compared to using single elements in excessive amounts
3Strength
If high-carbon composition is used to achieve high strength, then tensile strength is improved, but plastic toughness deteriorates
Solution Approach 1:
The patent optimizes the carbon content parameter within a specific range (0.84-0.89%) rather than using excessive carbon. This controlled carbon level provides high strength foundation while avoiding severe embrittlement. The combination with specific amounts of alloying elements and the refined sorbite structure formation during controlled rolling and air cooling ensures both high strength (≥1320 MPa) and adequate plasticity (area reduction ≥30%) are achieved simultaneously
4Strength
If complex heat treatment processes are applied to achieve high strength and high plasticity, then mechanical properties are improved, but manufacturing precision control becomes more difficult
Solution Approach 1:
The patent extracts and eliminates the offline isothermal treatment step from the process flow. By designing a specific chemical composition and applying controlled rolling followed by air cooling, the wire rod directly forms a refined sorbite structure during production, achieving high strength and good plasticity simultaneously. This simplification reduces the number of process steps and quality control checkpoints required, making manufacturing more manageable
Solution Approach 2:
The patent performs preliminary action by optimizing the chemical composition and controlling the rolling parameters during the main production process itself. The controlled rolling temperature range (950-1150°C) and cooling rate are designed to pre-establish the refined sorbite structure formation conditions, so that when air cooling occurs, the desired microstructure forms automatically without requiring subsequent corrective heat treatment, thereby simplifying quality control
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 solution results in wire rods with a tensile strength of ≥1320 MPa and area reduction rate of ≥30%, enabling the production of galvanized steel wires with ≥2000 MPa tensile strength and ≥11 times torsion value, suitable for bridge cables, at lower production costs.
Implementation Method 1
V and Al elements are prone to combine with C and N to form nanoscale carbon-nitride precipitates
Implementation Method 2
increasing the grain boundary area, providing more nucleation points for the transformation of sorbite structure
Implementation Method 3
Al also combines with O to form aluminum oxide
Implementation Method 4
refining the austenite structure
Implementation Method 5
providing more nucleation points for the transformation of sorbite structure
Implementation Method 6
Si solid-dissolved in the ferrite phase of the wire rod will significantly increase the strength of the material
Implementation Method 7
Si element will further be enriched at the interface between the ferrite phase and the cementite phase
Implementation Method 8
A refined sorbite lamellar structure possesses better deformation performance and work hardening performance
Data Source
AI summary
Disclosed in the present invention is a high-strength economical high-carbon steel wire rod, comprising Fe and inevitable impurities, and further comprising the following chemical elements in percentage by mass: C: 0.84%-0.89%; Si: 0.60%-1.00%; Mn: 0.30%-0.80%; Cr: 0.25%-0.50%; V: 0.02%-0.06%; Al: 0.02%-0.05%; O: 0.0015%-0.0035%; and N: 0.004%-0.008%. Correspondingly, also disclosed in the present invention is a manufacturing method for the wire rod. According to the present invention, by means of a reasonable chemical component design, the processing requirements of 2000MPa high-strength high-torsion zinc-plated steel wires can be met at low processing cost.