Brazed Carbide-Steel Tool Joint With Uniform Hardness Profile
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Solution Overview
Problem
Existing methods for joining steel with cemented carbide by brazing or welding face challenges such as differences in thermal expansion, strength of the braze joint, undesired hardness profiles, and wear resistance, particularly when threading is involved, leading to issues with fastening cutting tools.
Innovation Solution
A tool comprising a cemented carbide part and a steel part with specific compositions, joined by an active brazing process using a Ti-containing braze material that forms a TiC layer, followed by quenching and tempering, to achieve a strong, even hardness profile and improved wear resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If induction heating using a coil is used to heat the braze joint, then local heating is achieved leaving the rest of the tool unaffected, but unwanted hardness profiles are created in the steel part
Solution Approach 1:
The heating process is divided into two distinct stages: first, localized induction heating to melt the braze material and create the joint; second, furnace heating to uniformly heat the entire steel part and eliminate hardness gradients. This segmentation allows each heating method to perform its optimal function without causing adverse effects.
Solution Approach 2:
The induction heating is performed first as a preliminary step to establish the braze joint, followed by the furnace heating step that preliminarily addresses the hardness profile issue before final cooling and tempering. The sequence ensures that the hardness uniformity problem is addressed after the joint is already formed.
2Manufacturing precision
If the whole steel and cemented carbide part is heated to make the hardness profile more even, then hardness uniformity is improved, but the increased temperature affects the whole steel part and leads to less hardness overall
Solution Approach 1:
The steel composition is specifically adjusted with higher carbon content (0.63-0.70 wt%) and optimized alloying elements to ensure that even after uniform heating and cooling, the steel achieves and maintains the required hardness range (390-510 HV30). This compositional parameter change compensates for the softening effect of uniform heating.
Solution Approach 2:
The use of a specifically formulated steel composition acting as a composite material system with optimized carbon and alloy content allows the steel to maintain high hardness properties even after experiencing uniform thermal cycles that would normally reduce hardness in conventional steels.
3Ease of operation
If the steel part is provided with threading for fastening cutting tools, then tool attachment is enabled, but wear of the threading affects fastening negatively over time
Solution Approach 1:
The steel composition is modified with increased carbon content (0.63-0.70 wt%) and specific alloying elements to achieve high hardness (390-510 HV30) in the threaded regions, which significantly improves wear resistance while maintaining the threading functionality for tool fastening.
4Temperature
If individual tool handling is used for coil heating, then precise local heating is achieved, but automation and industrial production efficiency are reduced
Solution Approach 1:
The manufacturing process is segmented into distinct stages: induction heating for joint formation, furnace heating for hardness uniformity, and furnace cooling/tempering for final properties. This segmentation allows the first stage to maintain precision while subsequent stages can be automated, improving overall productivity without sacrificing joint quality.
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 method results in a tool with a predictable, high-strength braze joint and a steel part with consistent hardness, enhancing wear resistance and facilitating efficient industrial production.
Implementation Method 1
Joining steel with cemented carbide by brazing or welding has been known for a long time in the art of making tools
Implementation Method 2
one of the most common ways is induction heating using an induction coil
Implementation Method 3
a Ti-containing braze material that forms a TiC layer
Implementation Method 4
followed by quenching and tempering, to achieve a strong, even hardness profile
Implementation Method 5
followed by quenching and tempering, to achieve a strong, even hardness profile
Data Source
AI summary
A tool includes a cemented carbide part and a steel part joined by brazing, where the steel part has an average hardness of between 390 and 510 HV30. The braze joint includes Ti and a TiC layer, with a thickness of between 0.03 and 5 μm, adjoining to the cemented carbide part. The tool provides a strong braze joint and a steel part that have an even hardness.