Roll-Bonded Metal Sheet Composition for Low-Temperature Toughness
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Solution Overview
Problem
Current methods for producing roll-bonded sheets with high toughness, particularly those meeting API 5L and DNV OS-F101 standards, face challenges in achieving the required toughness at lower temperatures or maintaining toughness as the thickness of the sheets increases, due to limitations in the final rolling temperature and metallurgical bond integrity.
Innovation Solution
A method involving a thermomechanical rolling process with a nickel-based support material having a reduced Niobium (Nb) content, allowing for a lower final rolling temperature without weakening the metallurgical bond, thereby enhancing the toughness of the carbon steel base material. This process includes a first rolling phase for pre-rolling, a cooling period, and a second rolling phase at a temperature of 880 °C or lower, ensuring improved toughness properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the final rolling temperature is reduced to improve toughness, then the toughness of the base material is improved, but the metallurgical bond between the overlay material and base material is weakened or destroyed
Solution Approach 1:
The patent changes the chemical composition parameters of the overlay material, specifically reducing Nb content to ≤2.5% and controlling N content to ≤0.014%, which allows the metallurgical bond to remain intact at lower final rolling temperatures (≤880°C, particularly 850°C) that would otherwise weaken or destroy the bond in conventional materials
Solution Approach 2:
The patent creates a composite material system with specific composition ratios between overlay material (nickel-based alloy with controlled Nb and N) and base material (carbon steel), where the optimized composition enables simultaneous achievement of strong metallurgical bonding and high toughness at reduced rolling temperatures
2Strength
If the final rolling temperature is reduced to improve toughness, then the toughness of the base material is improved, but the sheet thickness must be limited
Solution Approach 1:
By changing the chemical composition parameters of the overlay material (reducing Nb to ≤2.5% and N to ≤0.014%), the patent enables the production of thicker sheets (up to 40mm base material thickness) at reduced final rolling temperatures (850°C), whereas conventional materials would require higher temperatures that compromise toughness
3Reliability
If conventional overlay material composition is used, then the metallurgical bond is maintained at higher rolling temperatures, but the toughness of the base material cannot be improved at lower temperatures
Solution Approach 1:
The patent optimizes the chemical composition parameters of the overlay material by reducing Nb content to ≤2.5% and controlling N content to ≤0.014%, which shifts the bonding behavior to allow strong metallurgical bonds to form and persist at lower rolling temperatures (≤880°C, particularly 850°C), enabling toughness improvement without sacrificing bond integrity
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 improves the toughness of roll-bonded sheets by reducing the Nb content in the support material, allowing for lower final rolling temperatures that maintain the metallurgical bond, resulting in enhanced toughness and compliance with industry standards even at thicker sheet thicknesses.
Implementation Method 1
heating the layer package
Implementation Method 2
a metallurgical bond is created between the individual layers by rolling at elevated temperature
Implementation Method 3
a cooling period between the first rolling phase and the second rolling phase
Data Source
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AI summary
A method for producing a roll-bonded metal sheet comprises bringing together a metallic main material layer and a metallic plating material layer to produce a layer stack. The layer stack is then heated. This is followed by thermomechanical rolling of the heated layer stack, comprising: a first rolling phase for rough rolling the heated layer stack to form a metallurgical bond between the metallic main material layer and the metallic plating material layer; a second rolling phase for finally forming the layer stack; and a cooling period between the first rolling phase and the second rolling phase. The chemical composition of the plating material has a content in mass % of Nb ≤ 3.1, preferably of Nb ≤ 2.8, in particular of Nb + Ta ≤ 2.8. The final rolling temperature of the second rolling phase is set to a value less than or equal to 880°C, in particular 850°C.