In-Line Steel Tube Processing for Uniform Circumference Properties
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Solution Overview
Problem
The manufacturing of steel tubes often results in mechanical properties that are compromised due to deformation during roll forming and welding, leading to reduced ductility and varying properties along the tube circumference, including the weld and heat-affected zone, which limits design flexibility and requires multiple tool sets for different strength levels.
Innovation Solution
A method involving an in-line manufacturing process where steel strips are roll formed, welded, and heat treated in a controlled atmosphere to achieve a microstructure with at least 50% austenite, followed by specific cooling trajectories to reintroduce ferrite and/or bainite, ensuring uniform mechanical properties across the tube circumference, including the weld zone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If steel strip is roll formed and seam welded to manufacture tubes, then production efficiency is improved, but ductility is reduced due to deformation and welding effects
Solution Approach 1:
The patent applies parameter changes by implementing a controlled heat treatment process with specific temperature ranges (Ac1-Ac3 transformation zones) and holding times to transform the microstructure of the steel tube. This heat treatment modifies the material parameters to achieve uniform mechanical properties including improved ductility while maintaining the benefits of roll forming and welding production efficiency.
Solution Approach 2:
The patent utilizes phase transitions by heating the steel tube to achieve austenite formation (at least 50% austenite phase) and then controlling the cooling trajectory to re-introduce ferrite and/or bainite in desired volume fractions. This controlled phase transition process uniformizes the microstructure across the tube circumference, including the weld zone, thereby improving ductility without sacrificing production efficiency.
2Strength
If multiple tool sets are used for different strength levels, then mechanical property requirements are met, but device complexity and cost increase
Solution Approach 1:
The patent applies universality by developing a single in-line manufacturing process that can produce steel tubes with uniform mechanical properties suitable for multiple strength levels. The controlled heat treatment process with adjustable temperature and time parameters can be tuned to achieve different mechanical properties from the same base material, eliminating the need for multiple dedicated tool sets for different strength requirements.
Solution Approach 2:
The patent uses parameter changes in the heat treatment process (temperature, holding time, cooling rate) to achieve different mechanical properties from the same manufacturing line. By adjusting these parameters, the process can produce tubes with varying strength levels while maintaining uniform properties throughout, reducing the need for multiple specialized tool sets.
3Stability of the object's composition
If weld seam is positioned at least deformed location, then local property variations are minimized, but design flexibility is reduced
Solution Approach 1:
The patent applies homogeneity by implementing a controlled heat treatment process that creates a uniform microstructure throughout the entire tube circumference, including the weld zone and heat-affected areas. By achieving at least 50% austenite phase and then controlling the cooling trajectory to produce uniform ferrite and/or bainite distribution, the process eliminates local property variations without constraining weld seam positioning, thereby maintaining design flexibility.
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
This process enhances the ductility and strength of steel tubes, achieving uniform mechanical properties and reducing the need for multiple tool sets, thereby improving design flexibility and cost-effectiveness in producing advanced high-strength steel tubes.
Implementation Method 1
the heat treatment comprises a heating regime such that in successive cross-sections of the tube a microstructure is achieved which holds at least 50 vol% austenite and a cooling trajectory to re-introduce ferrite, and/or bainite in desired volume fraction
Implementation Method 2
giving the tube a heat treatment, characterised in that the mentioned steps are performed in one continuous in-line manufacturing line, the heat treatment comprises a heating regime such that in successive cross-sections of the tube a microstructure is achieved which holds at least 50 vol% austenite
Implementation Method 3
a cooling trajectory to re-introduce ferrite, and/or bainite in desired volume fraction
Data Source
AI summary
A method for manufacturing of steel tube from a long steel strip, including providing a length of steel strip material to the process, forming a tube of the steel strip material, welding the formed tube in longitudinal direction, giving the tube a heat treatment wherein the mentioned steps are performed in one continuous in-line manufacturing line and the heat treatment includes a heating regime such that in successive cross-sections of the tube a microstructure is achieved which holds at least 50 vol % austenite and a cooling trajectory to re-introduce ferrite, and/or bainite in desired volume fractions.