Roll-Bonded Clad Sheet Rolling for Low-Temperature Toughness
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Solution Overview
Problem
Existing roll-bonded clad metal sheets face challenges in achieving high toughness, especially at lower temperatures and thicker thicknesses, due to the deterioration of mechanical properties during thermomechanical rolling.
Innovation Solution
A process involving a nickel-based cladding material with a reduced niobium (Nb) content, combined with thermomechanical rolling phases, allows for a lower final rolling temperature, thereby improving the toughness of the base material without weakening the metallurgical bond, using a nickel-based alloy with specific chemical compositions and controlled rolling temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional thermomechanical rolling is used with standard cladding materials, then the metallurgical bond is maintained, but the toughness of the base material deteriorates at lower temperatures
Solution Approach 1:
The patent modifies the chemical composition parameters of the cladding material, specifically reducing Nb content to ≤3.1% and controlling Nb+Ta≤2.8%, which changes the yield stress behavior of the cladding material. This parameter change enables the metallurgical bond to remain stable at lower rolling temperatures (≤880°C, particularly 850°C) where the base material achieves improved toughness properties.
Solution Approach 2:
The patent applies different quality requirements to different layers: the cladding material is designed with specific low Nb content to maintain bond stability, while the base material is processed to achieve high toughness. The cladding material's yield stress is reduced to be close to the base material's yield stress, creating a localized property distribution that allows low-temperature rolling to improve base material toughness without destroying the bond.
2Ease of manufacture
If standard cladding material composition is used, then corrosion resistance is maintained, but the yield stress difference between cladding and base material is too large preventing low-temperature rolling
Solution Approach 1:
The patent changes the compositional parameters of the cladding material by reducing Nb content (≤3.1%) and controlling Nb+Ta≤2.8%. This parameter change reduces the yield stress of the cladding material, bringing it closer to the base material's yield stress. This enables thermomechanical rolling at lower temperatures (≤880°C, particularly 850°C) which would otherwise be impossible due to the excessive yield stress difference in conventional cladding materials.
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 process enhances the toughness of roll-bonded clad metal sheets by reducing the yield stress difference between the cladding and base materials, enabling lower final rolling temperatures that maintain the metallurgical bond and improve mechanical properties, such as notched impact strength and fracture proportion, while maintaining corrosion resistance.
Implementation Method 1
heating of the layer packet; thermomechanical rolling of the heated layer packet
Implementation Method 2
a cooling time between the first rolling phase and the second rolling phase; the final rolling temperature of the second rolling phase is set to a value equal to or less than 880° C.
Data Source
AI summary
A roll-bonded clad metal sheet and a method for producing a roll-bonded clad metal sheet is provided. The roll-bonded clad sheet includes a metallic base material layer and a metallic cladding material layer which are joined to one another by a metallurgical bond. The metallic cladding material layer includes a nickel-based material whose chemical composition includes, in % by mass, a proportion of more than 50% of Ni and a proportion of 3.1% of Nb. The metallurgical bond is obtained by a thermomechanical rolling process including a first rolling phase for prerolling, a second rolling phase for final forming and a cooling time between the first rolling phase and the second rolling phase, wherein a final rolling temperature of the second rolling phase is set to a value equal to or less than 880° C.