Cemented Carbide Cutting Tool Oxygen Control
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Solution Overview
Problem
Existing cemented carbide cutting tools lack sufficient plastic deformation resistance for high-speed interrupted cutting, leading to deformation, wear, and reduced tool life when cutting complex-shaped forgings like carbon steel and alloy steel.
Innovation Solution
The oxygen content in the cemented carbide is controlled to 0.01 to 0.08 mass %, with a B1-type solid solution phase containing oxygen at 1 to 4 atomic % to enhance hardness and strength, inhibiting crack propagation and plastic deformation during high-speed interrupted cutting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxygen content and nitrogen content are reduced in the cemented carbide, then fracture resistance and wear resistance are improved, but plastic deformation resistance becomes insufficient for high-speed interrupted cutting
Solution Approach 1:
The invention changes the chemical composition parameters by precisely controlling oxygen content (0.005-0.200 wt%) and nitrogen content (0.005-0.200 wt%) within specific ranges, and by specifying the presence of B1-type solid solution phase with plate crystal WC. This parameter optimization resolves the contradiction by finding the optimal balance point where both fracture resistance and plastic deformation resistance are sufficient for high-speed interrupted cutting.
Solution Approach 2:
The invention creates a composite microstructure consisting of B1-type solid solution phase and plate crystal WC dispersed in the cemented carbide matrix. This composite structure combines the fracture resistance of reduced oxygen/nitrogen content with the plastic deformation resistance provided by the specific microstructure, resolving the contradiction between these two properties.
2Productivity
If high-speed cutting is performed to reduce machining costs, then productivity increases, but the cutting edge is heated and subjected to strong impact causing deformation
Solution Approach 1:
The invention utilizes plate crystal WC with high aspect ratio (curved/plate-like shape) that can absorb and distribute impact forces more effectively than equiaxed crystals. This curved/plate structure helps maintain cutting edge integrity under high-speed impact conditions, preventing deformation and maintaining cutting accuracy while enabling high productivity.
3Strength
If plate crystal WC is deposited by adding oxygen-containing compound powder, then hardness and strength are improved, but oxygen remaining in the B1-type solid solution phase lowers hardness and strength
Solution Approach 1:
The invention precisely controls the oxygen content parameter within a specific range (0.005-0.200 wt%) and specifies the nitrogen content range (0.005-0.200 wt%). By optimizing these chemical composition parameters and controlling the microstructure to include B1-type solid solution phase with plate crystal WC, the invention resolves the contradiction by preventing excess oxygen from remaining in the solid solution phase, thereby maintaining both hardness/strength and plastic deformation resistance.
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
This approach results in a cutting tool with improved wear resistance and fracture resistance, preventing plastic deformation and extending tool life by suppressing crack propagation and maintaining strength under high-temperature and high-impact conditions.
Implementation Method 1
a B1-type solid solution phase, expressed by M(CNO) or M(CO) where M is at least one selected from the group consisting of metals of the group IV, V, and VI in the periodic table, containing niobium as being essential, and containing oxygen at a rate of 1 to 4 atomic %
Data Source
AI summary
A cutting tool comprised of a cemented carbide is provided. The cemented carbide is consisted of a composition including: a predetermined amount of at least one selected from specific carbide, nitride, and carbon nitride, except for cobalt and niobium; 0.01 to 0.08 mass % of oxygen; and the rest consisted of tungsten carbide and unavoidable impurities. The cemented carbide is further made up of a structure in which a tungsten carbide phase and a B1-type solid solution phase being expressed by M(CNO) or M(CO) where “M” is at least one selected from the group consisting of metals of the group IV, V, and VI in the periodic table, containing niobium as being essential, and containing oxygen at a rate of 1 to 4 atomic % are bound by a binder phase composed mainly of the cobalt. This achieves the cutting tool having a long tool life in high-speed interrupted cutting.