Composite Pipe Structure Using TRIP/TWIP Steel for Corrosion Resistance
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Solution Overview
Problem
Existing methods for producing composite pipes for corrosive environments are costly due to the need for high-alloy steels with limited formability, which increases production costs and material expenses.
Innovation Solution
A composite pipe design featuring a support tube made of non-corrosion-resistant steel with a partially austenitic structure exhibiting TRIP and/or TWIP effects, combined with a corrosion-resistant protective tube, allowing for enhanced cold formability and reduced material thickness, thereby lowering production costs and improving mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-alloy steels with limited formability are used for the support tube, then corrosion resistance is improved, but production costs and material expenses increase
Solution Approach 1:
The patent applies local quality by providing corrosion protection only where needed - through a protective tube or coating on the support tube. The support tube itself uses cost-effective non-corrosion-resistant steel, while the protective layer provides localized corrosion resistance at the surface exposed to corrosive environments. This resolves the contradiction by eliminating the need for expensive high-alloy steels throughout the entire tube structure.
Solution Approach 2:
The patent employs composite material structure by combining non-corrosion-resistant steel support tube with a protective tube or coating layer. This composite approach allows each component to fulfill its specific function - the support tube provides structural integrity at low cost, while the protective layer provides corrosion resistance. This resolves the technical contradiction by achieving both cost-effectiveness and corrosion protection through material combination.
2Strength
If high-alloy steels with limited formability are used, then mechanical properties are improved, but cold formability deteriorates
Solution Approach 1:
The patent applies parameter changes by carefully controlling the chemical composition of the support tube steel (carbon content 0.05-2.5%, silicon 0.05-2.5%, manganese 1.0-5.0%, and optional alloying elements) to achieve optimal balance between mechanical strength and cold formability. The protective tube or coating is applied after forming, allowing the support tube to be formed using cost-effective, formable steels without compromising final mechanical properties.
Solution Approach 2:
The patent applies preliminary action by forming the support tube from non-corrosion-resistant steel with good formability first, then subsequently applying the protective tube or coating. This sequence allows the support tube to be manufactured using economical materials and processes, with mechanical properties enhanced by the protective layer applied in a preliminary manufacturing step rather than requiring expensive high-alloy steels from the outset.
3Reliability
If protective tube is added to provide corrosion resistance, then corrosion protection is improved, but device complexity increases
Solution Approach 1:
The patent applies merging by integrating the protective function directly onto the support tube through coating techniques or by tightly coupling a protective tube to the support tube. This combined structure provides both structural support and corrosion protection as a unified component system, reducing assembly complexity and eliminating the need for separate protective elements. The protective layer and support tube function together as an integrated corrosion-resistant structure.
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 composite pipe achieves excellent mechanical properties, including high strength, elongation, and toughness, enabling lightweight construction and reduced material usage while maintaining corrosion resistance, thus offering a cost-effective solution for corrosive environments.
Implementation Method 1
non-corrosion-resistant steel which has at least a partially austenitic structure and which, when exposed to mechanical stresses has a TRIP and/or TWIP effect
Implementation Method 2
non-corrosion-resistant steel which has at least a partially austenitic structure and which, when exposed to mechanical stresses has a TRIP and/or TWIP effect
Implementation Method 3
A non-positive connection is created between the outer tube and the inner tube in the sense of a press fit by mechanical shrinking
Implementation Method 4
hydraulically expanding the inner pipe with or without simultaneous heating of the outer pipe
Data Source
Figure 1a
Figure 1b
Figure 1c
AI summary
The invention relates to a composite pipe consisting of a carrier pipe (2) and at least one protective pipe (3), wherein the carrier pipe (2) is produced from a non-corrosion resistant steel, which has at least a partially austenitic structure, with the following chemical composition (in wt.%): C: 0.005 to 1.4; Mn: 5 to 35; the remainder being iron including unavoidable elements accompanying steel, with the optional alloying of the following elements (in wt.%): Ni: 0 to 6; Cr: 0 to 9; Al: 0 to 15; Si: 0 to 8; Mo: 0 to 3; Cu: 0 to 4; V: 0 to 2; Nb: 0 to 2; Ti: 0 to 2; Sb: 0 to 0.5; B: 0 to 0.5; Co: 0 to 5; W: 0 to 3; Zr: 0 to 4; Ca: 0 to 0.1; P: 0 to 0.6; S: 0 to 0.2; N: 0.002 to 0.3. The invention also relates to a method for producing such a composite pipe (1) of this type, wherein the carrier pipe (2) and the at least one protective pipe (3) are mechanically or metallurgically connected to one another.