Strain Aging Resistant Steel via Boron Nitride Formation
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Solution Overview
Problem
The steel industry faces challenges with strain aging in steel production, particularly in high-carbon steel, due to high nitrogen content, which reduces ductility and increases brittleness, leading to cracking and breaking during forming processes, and existing methods to control nitrogen content are costly and inefficient.
Innovation Solution
Adding boron to the steel to form boron nitride, stabilizing free nitrogen and reducing its content to below 80 ppm, thereby enhancing strain aging resistance, which can be achieved through deoxidization, analysis, and casting processes in electric arc furnaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional methods are used to control nitrogen content in steel, then nitrogen content can be reduced, but production costs increase significantly
Solution Approach 1:
The invention changes the chemical composition parameter by adding boron to the steel, which has a high affinity for nitrogen. This causes nitrogen to form boron nitride compounds, effectively reducing free nitrogen content to below 80 ppm without requiring expensive conventional nitrogen removal processes.
Solution Approach 2:
Boron acts as an intermediary substance that mediates between the harmful nitrogen and the steel matrix. By introducing boron, nitrogen is bound into stable boron nitride compounds, preventing it from causing strain aging while avoiding the need for costly nitrogen extraction methods.
2Reliability
If nitrogen content is reduced to prevent strain aging, then ductility and toughness are maintained, but manufacturing complexity increases
Solution Approach 1:
The invention performs preliminary action by adding boron during the steelmaking process itself, rather than attempting to remove nitrogen after the steel is formed. This proactive approach prevents strain aging from occurring in the first place, simplifying the overall manufacturing process.
Solution Approach 2:
By changing the chemical parameter through boron addition, the steel's nitrogen binding capacity is enhanced, automatically preventing strain aging without requiring additional complex processing steps or equipment.
3Strength
If high-carbon steel is heat-treated to increase hardness, then strength improves, but toughness and ductility are lost
Solution Approach 1:
The invention converts the typically harmful effect of nitrogen (which causes strain aging and brittleness) into a beneficial outcome by using boron to bind nitrogen into stable compounds. This allows the steel to maintain both high strength from heat treatment and adequate toughness by preventing nitrogen-induced embrittlement.
Solution Approach 2:
By controlling the nitrogen content through boron addition, the steel's microstructure can be optimized to achieve both high hardness and maintained toughness, resolving the traditional trade-off between strength and ductility in high-carbon steels.
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 method effectively reduces free nitrogen content, preventing strain aging and improving the steel's resistance to brittleness, allowing for the production of high-carbon steel wires that maintain ductility and toughness without increasing production costs or reducing throughput.
Implementation Method 1
adding boron to the steel wherein substantially all of the boron in the steel forms boron nitride, stabilizing the free nitrogen in the steel
Implementation Method 2
the furnace is charged with the scrap steel, and three graphite electrodes inside the furnace create electric arcs that melt the steel scrap into liquid steel
Implementation Method 3
if a basic oxygen furnace is used, the furnace is charged with a mixture of scrap and liquid pig iron, and oxygen is blown into the liquid steel to melt the scrap and purify the steel
Data Source
AI summary
A method for making a strain aging resistant steel comprises adding boron to the steel, wherein substantially all of the boron in the steel forms boron nitride. A method for making steel comprises adding a nitride-forming element to the steel to lower the free nitrogen content of the steel to a free nitrogen content specification. A high-carbon steel contains boron nitride, wherein the free nitrogen content of the steel is less than 80 ppm. A strain aging resistant steel wherein the carbon content of the steel is between about 0.54 percent and about 0.75 percent.