Friction Stir Welding Tool Cemented Carbide Al2O3 Coating
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Solution Overview
Problem
Friction stir welding tools for steel face challenges with high temperature mechanical strength, wear resistance, and oxidation resistance, leading to potential tool failure and reduced lifespan.
Innovation Solution
A friction stir welding tool made of cemented carbide with WC grains and a binder phase containing 3-10 wt% Ni, coated with a surface layer of Al2O3 and optionally Ti or Zr compounds, providing high hot hardness, mechanical strength, and resistance to thermo-mechanical fatigue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a friction stir welding tool is made of hard metal for high temperature welding, then mechanical strength at high temperature is improved, but oxidation resistance and wear resistance deteriorate
Solution Approach 1:
The invention uses a composite material consisting of cemented carbide (WC-Co-Ni) as the base material and Al2O3 as a surface coating layer. This composite structure combines the high mechanical strength and hot hardness of cemented carbide with the excellent oxidation resistance of aluminum oxide coating, thereby resolving the contradiction between mechanical strength and oxidation resistance at high temperatures.
Solution Approach 2:
The invention modifies the chemical composition parameters of the cemented carbide by specifying 3-10 wt% Ni content and 6-12 wt% Co content, and controls the coating thickness parameters (1-10 μm for Al2O3, 0.1-5 μm for intermediate layers). These parameter optimizations ensure both high temperature mechanical strength and sufficient oxidation resistance.
2Productivity
If the probe is exposed to high temperature for welding steel, then welding capability is improved, but tool lifetime deteriorates due to oxidation and wear
Solution Approach 1:
The Al2O3 coating is applied in advance to the cemented carbide tool surface before welding operations. This preliminary protective action creates a barrier layer that prevents oxidation and wear during high temperature welding, thereby extending tool lifetime without compromising welding capability.
Solution Approach 2:
The Al2O3 coating acts as a sacrificial protective layer that can be relatively thin (1-10 μm) compared to the bulk tool material. This thin coating provides sufficient protection for extended tool life while being cost-effective to apply, allowing the tool to withstand high temperature welding conditions.
3Reliability
If a surface coating is applied to improve oxidation resistance, then oxidation resistance is improved, but manufacturing complexity increases
Solution Approach 1:
The invention applies surface coating only to the critical areas of the tool that require oxidation protection, such as the probe and shoulder surfaces exposed to high temperature and oxygen during welding. This localized coating approach improves oxidation resistance while minimizing the complexity of the coating process compared to coating the entire tool.
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 enhanced wear resistance, oxidation resistance, and thermo-mechanical fatigue resistance, enabling prolonged and predictable use at high temperatures for welding various metallic materials, including steel, with improved chemical and oxidation resistance.
Implementation Method 1
the welding tool is at least partly coated with a surface coating comprising Al2O3... high oxidation resistance
Implementation Method 2
said cemented carbide comprises from 3 wt % to 10 wt % Ni... high hot hardness, high mechanical strength
Implementation Method 3
The friction stir welding tool according to the invention has a high hot hardness, high mechanical strength and is resistant to thermo-mechanical fatigue
Data Source
AI summary
A friction stir welding tool for welding of metallic plates and especially steel plates. The friction stir welding tool is made of cemented carbide comprising WC grains in a binder phase and wherein the welding tool is at least partly coated with a surface coating comprising Al2O3.