Tempered Transition Zone in Hot-Stamped B-Pillars for Joint Ductility
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Solution Overview
Problem
Structural components for automotive vehicles often face challenges in achieving zones of high strength and ductility, with existing methods being complex and costly, and lacking effective energy absorption during impacts without fracturing at joints.
Innovation Solution
A structural component with a transition zone of intermediate ductility formed by heating adjacent portions of high strength and high ductility steel parts, using existing materials like Usibor and Ductibor, and a localized tempering process in a laser trimming cell to reduce costs and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If in-die tempering processes are used to form transition zones, then the structural component achieves improved ductility at joints, but additional tooling costs and maintenance costs are incurred
Solution Approach 1:
A susceptor layer is applied to the steel blank which acts as an intermediary medium to absorb electromagnetic energy from the induction heating system and convert it to thermal energy, enabling localized tempering of the transition zone without requiring complex in-die tempering tooling
Solution Approach 2:
The mechanical in-die tempering system is replaced with an electromagnetic induction heating system that uses electromagnetic fields to heat the transition zone through the susceptor layer, eliminating the need for complex mechanical tooling and contact-based heating mechanisms
2Reliability
If in-die tempering processes are used to form transition zones, then the structural component achieves improved ductility at joints, but additional maintenance costs and quality control costs are incurred
Solution Approach 1:
The susceptor layer serves as a mediator that enables controlled, localized heating of the transition zone through electromagnetic induction, providing a simpler and more cost-effective alternative to in-die tempering while maintaining consistent quality
Solution Approach 2:
The susceptor layer self-heats when exposed to the induction heating field, converting electromagnetic energy to thermal energy directly at the target location, which eliminates the need for complex external heating systems and reduces quality control requirements
3Reliability
If welded steel blanks are used to achieve zones of different strength and ductility, then the structural component achieves high strength and high ductility zones, but the process complexity and cost increase
Solution Approach 1:
Instead of creating different material zones through welding, the invention applies local quality by selectively tempering only the transition zone adjacent to the weld joint, leaving the base materials unchanged while achieving the desired ductility gradient locally where needed
Solution Approach 2:
The invention changes the physical parameter (ductility) of the transition zone through controlled thermal tempering after welding, rather than changing the material composition or structure through welding different materials, thereby simplifying the overall process
4Ease of manufacture
If induction heating with susceptor layer is used to form transition zone, then the manufacturing cost and process complexity are reduced, but the heating system must be designed to work outside the forming die
Solution Approach 1:
The manufacturing process is segmented into distinct stages: welding/assembly followed by separate induction heating treatment, allowing the heating system to be positioned independently outside the forming die while maintaining process efficiency and reducing integration 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
The transition zone enhances energy absorption during impacts, reduces the risk of joint failure, and allows for adjustable dimensions without additional tooling costs, simplifying the manufacturing process and reducing capital investment.
Implementation Method 1
The localized transition zone of the structural component can be formed by tempering using a relatively inexpensive induction heating system
Implementation Method 2
The structural component includes a first steel blank welded to a second steel blank using a laser beam welding system
Data Source
AI summary
The invention provides a hot stamped structural component (20) for an automotive vehicle, such as a B-pillar, including a first part (22) formed of a high strength steel material joined to a second part (24) formed of a high ductility steel material. The structural component (20) also includes a locally tempered transition zone (26) along the joint (28) to reduce the potential for failure along the joint (28). The transition zone (26) has strength and ductility levels between the strength and ductility levels of the remaining portions of the first and second parts (22, 24). The tempering step can be incorporated into a laser trimming cell or assembly cell, and thus the transition zone (26) can be created without adding an additional process step or increasing cycle time.