Multilayer Tool Coating for Hot Stamping Wear Resistance
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Solution Overview
Problem
Forming tools used in hot stamping processes experience high levels of abrasive and adhesive wear due to high temperatures and rapid quenching rates, leading to reduced tool life and increased maintenance needs.
Innovation Solution
A multilayer coating system comprising CrN, TiAlN, and VCN layers, deposited using PVD methods, providing enhanced resistance to abrasive and adhesive wear at temperatures up to 800°C, with a specific carbon and nitrogen content profile and additional layers for improved adhesion and load-bearing capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If conventional coatings are used on forming tools for hot stamping, then the tools can perform the forming process, but they experience high levels of abrasive and adhesive wear leading to reduced tool life
Solution Approach 1:
The patent applies a multilayer composite coating system consisting of alternating layers of CrN (chromium nitride) and TiAlN (titanium aluminum nitride) with specific thickness ratios. This composite structure combines the advantages of both materials: CrN provides excellent adhesive wear resistance while TiAlN provides superior abrasive wear resistance and hardness. The alternating layer structure creates a synergistic effect that significantly improves overall tool life and wear resistance compared to single-layer coatings.
Solution Approach 2:
The patent optimizes specific parameters including the thickness of each layer (CrN layers: 2-5 μm, TiAlN layers: 1-3 μm), the number of alternating layers (3-10 pairs), and the deposition conditions (PVD process parameters, substrate temperature 150-250°C, nitrogen partial pressure 0.1-0.5 Pa). These parameter optimizations ensure the coating achieves maximum wear resistance while maintaining adhesion to the substrate and resistance to thermal shock during hot stamping processes at temperatures up to 950°C.
2Temperature
If the forming process is conducted at high temperatures (800°C and higher), then press hardening of coated sheet materials can be achieved, but the level of adhesive and abrasive wear of the dies increases remarkably
Solution Approach 1:
The multilayer CrN/TiAlN composite coating is specifically designed to withstand high temperatures up to 950°C. CrN layers maintain their structural integrity and provide oxidation resistance at elevated temperatures, while TiAlN layers provide thermal stability and resistance to thermal shock. The alternating structure allows for thermal expansion management and prevents coating delamination during the hot stamping process, thereby maintaining wear resistance at forming temperatures of 800°C and higher.
Solution Approach 2:
The patent creates local quality variations within the coating structure by alternating between CrN and TiAlN layers, each with distinct properties optimized for specific functions. CrN layers are positioned to provide adhesive wear resistance and oxidation protection, while TiAlN layers provide abrasive wear resistance and hardness. This local differentiation of material properties within the coating system enables the tool to withstand both adhesive and abrasive wear mechanisms simultaneously at high temperatures.
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 coating system significantly extends tool life by reducing material transfer and wear, maintaining performance in hot stamping processes, outperforming conventional coatings in both adhesive and abrasive wear resistance tests.
Implementation Method 1
A multilayer coating system comprising CrN, TiAlN, and VCN layers, deposited using PVD methods
Data Source
AI summary
A coated tool for hot stamping of coated or uncoated sheet metals, comprising a coated substrate surface to be in contact with the coated or uncoated metal sheet, wherein the coating in the coated substrate surface comprises one or more inferior layers and one or more superior layers, where the inferior layers are deposited closer to the substrate surface than the superior layers, and:the inferior layers are designed for providing load bearing capacity,the superior layers are designed for providing galling resistance,at least one superior layer is deposited having a multi-nanolayer structure wherein:one type of nanolayer is composed of at least 90 at.-% of chromium and nitrogen,a second type of nanolayer is composed of at least 90 at.-% of titanium, aluminum and nitrogen,a third type of nanolayer is composed of at least 90 at.-% of vanadium carbon and nitrogen.