Composite Rolling Roll with MC Carbides in Tough Shaft Portions
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Solution Overview
Problem
Centrifugally cast composite rolls experience frequent damage due to wear and surface roughening, leading to premature discarding of shaft portions, which affects the durability and productivity of the rolling process.
Innovation Solution
Transferring hard MC carbides from the outer layer into the inner layer of graphite cast iron shaft portions without adding carbide-forming elements like V, enhancing the wear resistance of the shaft portions while maintaining toughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If carbide-forming elements like V are added to enhance wear resistance, then wear resistance improves, but toughness deteriorates
Solution Approach 1:
The invention extracts the harmful effect of adding carbide-forming elements to the inner layer by deliberately omitting V and other strong carbide-forming elements from the inner layer composition. Instead, the patent transfers MC carbides from the outer layer to the inner layer through controlled centrifugal casting, achieving wear resistance without the toughness-deteriorating side effects of adding carbide-forming elements directly to the inner layer.
Solution Approach 2:
The outer layer acts as an intermediary medium that contains the MC carbides. During centrifugal casting, these carbides are transferred from the outer layer to the inner layer through the molten metal flow, serving as a natural source of wear-resistant particles without requiring direct addition of carbide-forming elements to the inner layer, thus preserving toughness.
2Reliability
If frequent damage-removing grinding is performed to maintain surface quality, then surface quality is maintained, but productivity decreases and effective rolling diameter is reduced
Solution Approach 1:
The invention performs preliminary action by incorporating MC carbides into the inner layer shaft portions before the roll enters service. This pre-enhancement of wear resistance in the shaft portions prevents future damage and eliminates the need for frequent damage-removing grinding, thereby maintaining productivity and effective rolling diameter throughout the roll's service life.
Solution Approach 2:
The invention creates a composite structure where MC carbides are distributed within the graphite cast iron matrix of the inner layer shaft portions. This composite material approach provides exceptional wear resistance to the shaft portions, preventing damage that would otherwise require grinding interruptions and extending the effective rolling diameter range.
3Duration of action of stationary object
If the outer layer is made wear-resistant to extend roll life, then roll life extends, but shaft portions are likely damaged prematurely
Solution Approach 1:
The invention applies local quality by creating a non-uniform distribution of MC carbides specifically within the shaft portions of the inner layer, while maintaining the overall composite structure. The shaft portions contain 200/cm² or more MC carbides with 5μm diameter or more, providing localized wear resistance exactly where it is needed (in the high-stress shaft portions) without compromising the toughness of the inner layer matrix.
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 solution provides composite rolls with significantly improved wear resistance and extended life, reducing rolling costs and minimizing damage to shaft portions, thereby enhancing the durability and efficiency of the rolling process.
Implementation Method 1
a centrifugally cast outer layer of a wear-resistant iron-based alloy is integrally fused to a tough inner layer of ductile cast iron
Implementation Method 2
an outer layer having excellent wear resistance and impact resistance is integrally fused to an inner layer having excellent toughness and wear resistance
Data Source
Figure 1~2
Figure 3(a)~3(b)
Figure 4
AI summary
A composite roll for rolling comprising an outer layer and an inner layer integrally fused to each other; the outer layer being made of an Fe-based alloy comprising by mass 1-3% of C, 0.3-3% of Si, 0.1-3% of Mn, 0.1-5% of Ni, 1-7% of Cr, 1-8% of Mo, 4-7% of V, 0.005-0.15% of N, and 0.05-0.2% of B; the inner layer being made of graphite cast iron comprising by mass 2.4-3.6% of C, 1.5-3.5% of Si, 0.1-2% of Mn, 0.1-2% of Ni, less than 0.7% of Cr, less than 0.7% of Mo, 0.05-1% of V, and 0.01-0.1% of Mg; the inner layer comprising a core portion fused to the outer layer, and shaft portions integrally extending from both ends of the core portion; at least one of the shaft portions containing 200/cm2 or more of hard MC carbides having circle-equivalent diameters of 5 µm or more.