Hot-Press Steel Plate Molding With Differential Cooling Zones
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Solution Overview
Problem
Existing hot-press molding methods produce products with uniform characteristics, failing to achieve desired variations in strength and ductility across different parts, particularly in larger products where specific characteristics are required for safety and efficiency.
Innovation Solution
A hot-press molding method involving a first heating process to austenitize the steel plate, followed by differential cooling to create martensite and austenite regions, a reheating process to temper martensite, and a final cooling process to stabilize structures, allowing for the creation of products with distinct hardness and strength characteristics across different parts during molding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the entire steel plate is uniformly cooled after heating to austenite, then high strength is obtained throughout the product, but uniform characteristics are produced which fail to meet varying requirements for different parts
Solution Approach 1:
The patent applies local quality by implementing differential cooling rates across different regions of the steel plate. Specifically, a first region is rapidly cooled to produce martensite for high strength, while a second region is slowly cooled to retain austenite for high ductility. This allows each part of the molded article to have locally optimized properties matching its functional requirements.
2Strength
If the steel plate is rapidly cooled to produce martensite, then high strength is obtained, but high ductility is lost
Solution Approach 1:
The patent creates spatial differentiation in material properties by applying different cooling rates to different regions. The first region undergoes rapid cooling to form martensite with high strength, while the second region undergoes slow cooling to retain austenite with high ductility, thus simultaneously satisfying both requirements in different locations of the same component.
Solution Approach 2:
The steel plate is functionally segmented into two distinct regions with different thermal histories and resulting microstructures. The first region is designated for high-strength applications with martensitic structure, while the second region is designated for high-ductility applications with retained austenite, allowing the component to meet diverse performance requirements.
3Adaptability or versatility
If the steel plate is heated to austenite and then cooled to produce different regions, then varying characteristics are obtained, but the process complexity increases
Solution Approach 1:
The patent controls the cooling rate parameter differently for different regions of the steel plate. By adjusting the cooling rate (rapid cooling for first region, slow cooling for second region) during the molding process, the microstructure and properties of each region are controlled, achieving varying characteristics without adding significant process complexity.
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
Enables the production of hot-press molded products with varying characteristics, such as high strength and high ductility, by controlling cooling and reheating processes, resulting in parts with significant hardness differences and tailored properties.
Implementation Method 1
a first heating process in which a steel plate is heated and the entire steel plate becomes austenite
Implementation Method 2
a first cooling process in which a cooling rate of the steel plate after the first heating process is partially changed, a first region which is a part of the steel plate is transformed into martensite
Implementation Method 3
a second heating process in which the entire steel plate is reheated and the first region becomes tempered martensite
Implementation Method 4
a second cooling process in which the entire steel plate after the second heating process is cooled
Data Source
AI summary
A hot-press molding method of the present disclosure includes a first heating process in which a steel plate is heated and the entire steel plate becomes austenite, a first cooling process in which a cooling rate of the steel plate after the first heating process is partially changed, a first region which is a part of the steel plate is transformed into martensite, and a second region other than the first region remains as austenite, a second heating process in which the entire steel plate is reheated and the first region becomes tempered martensite, and a second cooling process in which the entire steel plate after the second heating process is cooled. At least one of the first cooling process and the second cooling process is performed during a molding process in which the steel plate is press-molded on a molding die.