Composite Sintered Body Cutting Tool for Thermal Crack Resistance
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Solution Overview
Problem
Cutting tools made of composite sintered bodies with reduced tungsten content suffer from insufficient thermal crack resistance and abnormal damage such as chipping and fracture, especially during wet intermittent cutting, where high loads are applied intermittently.
Innovation Solution
A composite sintered body cutting tool is developed with a TiCN-based cermet layer and a WC-based cemented carbide layer, optimized in composition and thickness ratio to minimize deformation and enhance thermal crack resistance, featuring a WC-based cemented carbide layer on the rake face with a specific thickness and a TiCN-based cermet layer with controlled metal content, and optionally coated with a hard layer for improved wear resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If tungsten content is reduced in the cermet layer, then resource saving is achieved, but thermal crack resistance and abnormal damage resistance deteriorate
Solution Approach 1:
The patent changes the chemical composition parameters of the cermet layer by specifying precise ranges: W content (0-15 mass%), WC content (0-15 mass%), Mo content (5-20 mass%), Nb content (5-15 mass%), Cr content (2-10 mass%), and TiCN content (60-80 mass%). This parameter optimization allows reduction of tungsten while maintaining thermal crack resistance through compensating elements like Mo, Nb, and Cr that enhance high-temperature strength and crack resistance.
Solution Approach 2:
The patent creates a composite sintered body combining TiCN-based cermet layer with WC-based cemented carbide layer. This composite structure leverages the advantages of both materials: the TiCN-based cermet provides toughness and thermal crack resistance, while the WC-based cemented carbide provides hardness and wear resistance. The specific composition ranges and layer configuration enable reduced tungsten usage while maintaining or improving overall performance.
2Loss of substance
If tungsten content is reduced in the cermet layer, then resource saving is achieved, but abnormal damage resistance deteriorates
Solution Approach 1:
The patent optimizes composition parameters to balance tungsten reduction with maintaining strength. The cermet layer contains Mo (5-20 mass%) and Nb (5-15 mass%) which strengthen the matrix and improve abnormal damage resistance. The TiCN content (60-80 mass%) provides hardness while the controlled tungsten content (0-15 mass%) and WC content (0-15 mass%) maintain strength without excessive tungsten usage.
Solution Approach 2:
The composite structure with TiCN-based cermet layer (providing toughness and strength) and WC-based cemented carbide layer (providing hardness) creates synergistic effects. The interface between layers and the specific composition ranges enable the tool to resist abnormal damages like chipping and fracture while using less tungsten.
3Productivity
If the cutting tool is used in wet intermittent cutting with high loads, then productivity is maintained, but thermal crack and abnormal damage occur more frequently
Solution Approach 1:
The patent optimizes composition parameters for high-temperature strength and crack resistance: Cr content (2-10 mass%) improves oxidation resistance and high-temperature strength, Mo content (5-20 mass%) enhances thermal softening resistance, and the controlled TiCN content (60-80 mass%) provides thermal stability. These parameter changes enable the tool to withstand wet intermittent cutting conditions with thermal shocks and high loads.
Solution Approach 2:
The composite sintered body structure combines materials with complementary properties: TiCN-based cermet provides thermal crack resistance and toughness, while WC-based cemented carbide provides wear resistance. This composite structure enables the tool to maintain productivity in harsh cutting conditions while resisting thermal cracks and abnormal damages that would otherwise occur.
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 tool exhibits excellent abnormal damage resistance and wear resistance for long-term usage without compromising thermal crack resistance, even under high load and thermal stress conditions, while reducing tungsten usage.
Implementation Method 1
sintering in which they are held at 1300-1500° C. for 0.5-3 hours in the vacuum atmosphere
Implementation Method 2
the cemented carbide layer; and the cermet layer including 15-65 mass % or less of WC and W in total and 80 mass % or more of the iron group metal in the binder phase are Co, are laminated
Data Source
AI summary
A composite sintered body cutting tool is made of a composite sintered body comprising a TiCN-based cermet layer; and a WC-based cemented carbide layer. The angle between the rake face and the flank face of the cutting tool is 90°. The rake face including a cutting edge of the cutting tool is constituted from the WC-based cemented carbide layer, in which 4 to 17 mass % of an iron group metal component and 75 mass % or more of W are included; and a major hard phase component is WC. The thickness of the WC-based cemented carbide layer is 0.05 to 0.3 times the thickness of the composite sintered body. The TiCN-based cermet layer is constituted from a single layer of a TiCN-based cermet layer, including at least, 4 to 25 mass % of an iron group metal component, less than 15 mass % of W, 2 to 15 mass % of Mo, 2 to 10 mass % of Nb and 0.2 to 2 mass % of Cr in a case where contents of the constituting components of the cermet layer are expressed as contents of metal components, and satisfy the Co content relative to the total content of Co and Ni of 0.5 to 0.8 with respect to Co and Ni of the iron group metal component in a mass ratio. When the height profile from the upper end to the lower end of the flank face is measured in the plane, which passes the center of the rake face of the cutting tool and is perpendicular to both of the rake face and the flank face, as the line, which passes the ridge line where the rake face and the flank face intersect and perpendicular to the rake face, being the reference line, the maximum elevation difference value of the height profile is in a ratio of 0.01 or less with respect to the thickness of the composite sintered body from the front surface of the rake face to a rear surface.