Partial Hardening of Steel Components via Selective Austenitization
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Solution Overview
Problem
Existing press hardening methods face challenges in achieving partial hardening of steel components with high precision, energy efficiency, and high throughput, as they require complex processes and result in increased cycle times and energy demand, along with dimensional stability issues due to uneven cooling and twisting of parts.
Innovation Solution
A method involving a continuous furnace where components are heated to 700°C and then moved under three-dimensionally contoured radiating elements to selectively austenitize specific regions, allowing for precise partial heating and rapid cooling in a form hardening tool, using absorption masses to manage thermal energy and prevent overheating, thereby achieving distinct tensile strengths in different regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional press hardening methods are used for partial hardening, then hardening can be achieved, but the process complexity increases and cycle time extends
Solution Approach 1:
The heating process is segmented into two distinct stages: first heating the entire component to 700°C in a continuous furnace, then selectively heating only the regions requiring hardening to above Ac3 temperature using radiating elements. This segmentation allows precise control over which areas are hardened while simplifying the overall process architecture.
Solution Approach 2:
The component is preliminarily heated to 700°C in a continuous furnace before being transferred to the hardening station. This preliminary heating action prepares the entire component for selective austenitization in subsequent steps, enabling precise partial hardening without requiring complex real-time temperature control during the hardening phase.
2Manufacturing precision
If conventional heating methods are used for partial hardening, then selective hardening can be achieved, but energy consumption increases
Solution Approach 1:
The heating system applies different thermal treatments to different regions of the component. The continuous furnace provides uniform heating to 700°C for the entire component, while the radiating elements in the hardening station concentrate thermal energy only on specific regions that require austenitization and subsequent hardening, minimizing unnecessary energy consumption.
Solution Approach 2:
The continuous furnace enables uninterrupted heating of components to 700°C, maintaining optimal temperature for the desired duration without repeated heating cycles. This continuous thermal action improves energy efficiency compared to intermittent heating methods while ensuring uniform preliminary heating across all components.
3Manufacturing precision
If conventional heating methods are used, then hardening can be achieved, but cycle time increases
Solution Approach 1:
Components are preliminarily heated to 700°C in a continuous furnace before entering the hardening station. This preliminary heating eliminates the need for prolonged heating cycles during the hardening process itself, as the component is already at optimal temperature and only requires selective localized heating above Ac3, significantly reducing total cycle time.
Solution Approach 2:
The method skips the time-consuming phase of heating entire components from room temperature to austenitization temperature in conventional presses. Instead, components arrive pre-heated to 700°C and only require brief selective heating of specific regions, rushing through the time-intensive heating phase while maintaining precise hardening control.
4Manufacturing precision
If uneven cooling is applied for partial hardening, then selective hardening can be achieved, but dimensional stability deteriorates due to twisting
Solution Approach 1:
The cooling process is segmented into controlled phases where the hardening tool applies cooling pressure selectively to regions that were austenitized, while other regions cool more gradually. This segmented cooling approach maintains dimensional stability by controlling thermal gradients and preventing twisting, while still achieving selective hardening in the targeted areas.
Solution Approach 2:
The cooling rate and pressure parameters are changed and controlled during the hardening process. The hardening tool applies higher cooling rates and pressure to regions requiring hardening, while allowing other regions to cool more slowly, maintaining dimensional stability and preventing distortion while achieving the desired selective hardening effect.
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
This approach enables rapid, energy-efficient, and precise production of partially hardened steel components with reduced cycle times and improved dimensional stability, allowing for selective stress distribution during crash loads, while maintaining a low energy demand and high throughput capacity.
Implementation Method 1
heated to 700°C in a continuous furnace
Implementation Method 2
heated to 700°C in a continuous furnace
Implementation Method 3
moved under three-dimensionally contoured radiating elements to selectively austenitize specific regions
Implementation Method 4
austenitize specific regions, allowing for precise partial heating
Implementation Method 5
rapid cooling in a form hardening tool
Implementation Method 6
The quench hardening of the austenitic structure causes a martensitic hardening of the sheet metal component
Implementation Method 7
using absorption masses to manage thermal energy and prevent overheating
Data Source
AI summary
The invention relates to a method for producing partially-hardened components from steel sheets, in which a component that is cold-formed from a hardenable steel sheet material is heated, in a furnace, to a temperature below the austenitization temperature (<AC3), and a radiating element acts upon the component in sections where said component is to be austenitized (<AC3), this radiating element having a component-side contour that corresponds to the contour of the component in the section to be austenitized. The invention also relates to a device for carrying out said method.