Vehicle Side Member Fabrication via Localized Martensite Transformation
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Solution Overview
Problem
Conventional hot stamping methods for producing high-rigidity vehicle side members using boron steel fail to effectively distribute collision energy, leading to partial buckling and inadequate absorption performance, compromising vehicle safety.
Innovation Solution
A method involving hot press forming of boron steel blanks into martensite organization, followed by partial transformation to ferrite organization through induction heating or laser-based secondary heat treatment, to achieve improved toughness and stabilized collision energy absorption without additional reinforcement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If hot stamping forming is used to produce high-rigidity vehicle side members using boron steel, then rigidity and light-weight characteristics are improved, but collision energy absorption performance deteriorates due to inadequate energy distribution and partial buckling
Solution Approach 1:
The patent applies local quality by creating distinct metal organizations in different regions of the side member. The first metal organization (martensite) provides high rigidity in critical load-bearing areas, while the second metal organization (ferrite or tempered martensite) provides improved toughness and energy absorption in collision-prone regions. This spatial differentiation of material properties resolves the contradiction between overall rigidity and localized energy absorption.
Solution Approach 2:
The patent changes the metal organizational parameters through controlled heating and cooling processes. By applying induction heating or laser beam heating to specific regions followed by controlled cooling, the patent transforms the metal organization from martensite to ferrite or tempered martensite in targeted areas. This parameter change enables different regions to exhibit different mechanical properties, simultaneously achieving rigidity and energy absorption.
2Strength
If uniform martensite organization is maintained throughout the side member, then high-rigidity is achieved, but collision energy distribution becomes uneven leading to buckling
Solution Approach 1:
The patent introduces local quality variations by creating regions with different metal organizations within the side member. Instead of uniform martensite throughout, specific regions are transformed to ferrite or tempered martensite through localized heating and cooling. This creates a non-uniform but optimized structure where different regions serve different functions: rigidity in load-bearing areas and energy absorption in collision zones.
Solution Approach 2:
The patent segments the side member into regions with different metal organizations. By dividing the structure into zones with distinct material properties (first metal organization vs. second metal organization), the patent enables differentiated functionality across the component, allowing simultaneous optimization of rigidity and energy distribution stability.
3Reliability
If conventional steel materials are used for side members, then collision energy absorption is adequate, but weight increases and rigidity is insufficient
Solution Approach 1:
The patent creates a composite metal organizational structure within the side member by combining different metal organizations (martensite, ferrite, tempered martensite) in specific regions. This composite approach at the microstructural level allows the use of lighter boron steel material while achieving both the weight reduction goal and the collision energy absorption requirement through optimized material distribution.
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 method enhances collision energy absorption performance by evenly distributing energy across the vehicle body, reducing the risk of buckling and maintaining high-rigidity and light-weight characteristics, thus improving vehicle safety and manufacturing efficiency.
Implementation Method 1
the boron steel plate of ferrite organization having a tensile strength of 500 MPa to 800 MPa approximately before forming is formed at a temperature more than 900° C. through an austenitation, and a martensite organization M having a high-tensile strength of 1300 MPa to 1600 MPa through a quick cooling is obtained
Implementation Method 2
heating respectively pre-calculated position of the inner member and the outer member having a first metal organization of high-rigidity considering an directivity of an energy absorption to each transformation point secondarily through a heating source
Implementation Method 3
or to a metal organization heat treated by tempering process through induction heating or secondary heat treatment using laser beam LB of conduction area T2
Implementation Method 4
cooling respectively the inner member and the outer member formed by the hot forming secondarily with using a second cooling method so as to obtain a second metal organization having a partial low-rigidity comparably
Data Source
AI summary
As to the method for fabricating a member of a vehicle, after a member for the vehicle having high-rigidity of martensite organization is fabricated by a hot stamping forming, the martensite organization is transformed to a ferrite having a low-rigidity partially and improved toughness or to a metal organization heat treated by tempering process through induction heating or secondary heat treatment using laser beam of conduction area, and thereby collision absorption performance is improved by stabilizing the absorption directivity of the collision energy without additional reinforcement.