Fine-Grained Cemented Carbide Insert for HRSA Turning
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Solution Overview
Problem
Machining heat-resistant super alloys and stainless steels under wet conditions poses challenges due to increased cutting forces, wear, and thermal heat conductivity issues, leading to notch wear, flank wear, and plastic deformation, particularly in roughing and semi-roughing operations.
Innovation Solution
A coated cutting tool insert with a very fine-grained cemented carbide body, specifically tungsten carbide with controlled Co and Cr content, combined with a PVD (Ti,Al)N coating, enhances notch wear resistance and maintains flank wear resistance across various machining operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high temperature strength is increased in super alloys and stainless steels, then mechanical and chemical properties at elevated temperatures are improved, but cutting forces and wear on the cutting edge increase
Solution Approach 1:
The invention changes the microstructural parameters of the cemented carbide substrate by controlling WC grain size (0.4-1.0 μm) and binder phase composition (Cr/Co ratio of 0.05-0.15), enabling the tool to withstand increased cutting forces and wear when machining high-strength super alloys and stainless steels
Solution Approach 2:
The invention uses a composite structure combining fine-grained tungsten carbide particles with a controlled cobalt-chromium binder phase, creating a material that simultaneously provides hardness for wear resistance and toughness for withstanding cutting forces in high-temperature machining
2Temperature
If stronger materials are used to improve high temperature properties, then thermal resistance is improved, but heat generation during chip formation increases and thermal conductivity remains low, leading to very high cutting temperatures
Solution Approach 1:
The invention optimizes the binder phase composition with specific Cr/Co ratios (0.05-0.15) and controlled WC grain size to enhance thermal management properties, reducing cutting temperatures while maintaining resistance to thermal softening in high-temperature machining environments
3Reliability
If fine grained cemented carbide is used, then notch wear resistance is improved, but substrate hardness and resistance to plastic deformation must be maintained
Solution Approach 1:
The invention creates a composite microstructure with fine WC grains (0.4-1.0 μm) embedded in a controlled Cr-Co binder phase, where the fine grain structure provides notch wear resistance while the optimized binder composition maintains substrate hardness and resistance to plastic deformation
Solution Approach 2:
The invention carefully controls the Cr content and Cr/Co ratio (0.05-0.15) in the binder phase to achieve the optimal balance between fine grain structure for notch wear resistance and sufficient binder strength to prevent plastic deformation under cutting loads
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 significantly improves tool life by reducing notch wear and maintaining resistance against plastic deformation and flank wear, extending tool life in machining heat-resistant super alloys and stainless steels, even under wet conditions.
Implementation Method 1
a (Ti,Al)N PVD-coating
Data Source
Figure 1~2
Figure 3~4
AI summary
The present invention relates to a cutting insert for turning in heat resistant super alloys and stainless steels comprising a very fine grained hard substrate and a coating. The substrate comprises WC 5-8 wt-% Co and 0.3-1.5 wt-% Cr. Additionally, ppm levels of Ti, Ta, or mixtures of these, are present. The ratio of Me/Co= (at-%Ti+ at-%Nb+at-%Ta)/at-%Co is lower than or equal to 0.014-(CW_Cr)*0.008 and higher than 0.0005. The average sintered WC-grain size is 0.5-0.95 µm and CW_Cr 0.75-0.95. The cemented carbide body is coated with a PVD TixAl1-xN-coating with an average composition of 0.4<x<0.9 present as single or multilayer coating with a total thickness of >1 µm, but <6.0 µm. racterised in that the substrate comprises WC, 5-8 wt% Co, 0.3-1.5 wt% Cr, and ppm levels of Ta, Ti or mixtures thereof, present in such amounts that the ratio Me/Co=(at-%Ti+at-%Ta)/at-%Cc is lower than or equal to 0.014-(CW_Cr)*0.008 and higher than 0.0005, and CW_Cr is 0.75-0.95, wherein CW_Cr= (magnetic-% Co +1.13*wt-% Cr)/wt-% Co, wherein magnetic-% Co is the weight percentage of magnetic Co, wt-% Cr is the weight percentage of Cr and wt-% Co is the weight percentage of Co in the cemented carbide, and the coating is a PVD TixAl1-xN-coating with an average composition of 0.4<x<0.9 present as single or multilayer coating with a total thickness of >1 µm, but <6.0 µm.