Tailor Welded Blank Welding After Al-Fe Layer Removal
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The formation of ferrite during laser welding of aluminum-coated steel plates results in fractures in the weld zone, compromising the mechanical strength and integrity of tailor welded blanks, as the aluminum-rich region transforms into ferrite during cooling, leading to unintended softness and loss of intended function.
Innovation Solution
A method involving the preparation of a steel sheet with an aluminum-based plating layer that is heat-treated to form an Al-Fe-based intermetallic alloy layer, followed by the removal of this layer in the welding region before butt welding to prevent ferrite formation, ensuring a high-strength weld zone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If laser welding is performed on aluminum-coated steel plates, then welding efficiency and productivity are improved, but ferrite formation occurs in the weld zone causing fractures and loss of mechanical strength
Solution Approach 1:
The harmful aluminum-based plating layer is selectively removed from the welding region through methods such as sandblasting, grinding, or chemical treatment before laser welding. This extraction eliminates the source of ferrite formation while preserving the aluminum coating in non-welding areas for corrosion protection, thereby maintaining weld integrity without sacrificing overall productivity
Solution Approach 2:
The steel plate is given different surface conditions in different regions: the welding region has the aluminum plating layer removed to prevent ferrite formation, while non-welding regions retain the aluminum coating for corrosion protection. This local differentiation allows the component to meet both welding quality requirements and corrosion resistance requirements
2Strength
If the aluminum-based plating layer is removed before welding, then ferrite formation is prevented and weld strength is maintained, but additional processing steps are required increasing manufacturing complexity
Solution Approach 1:
The aluminum plating layer is removed in advance from the welding region before the actual laser welding process begins. By performing this preparation step beforehand, the welding process itself can proceed without interruption or modification, and the removed material can be managed systematically rather than dealing with ferrite formation issues during welding
Solution Approach 2:
An intermediary processing step (such as sandblasting, grinding, or chemical treatment) is introduced between the plating and welding operations. This intermediary process selectively removes the aluminum layer from welding areas while leaving it intact elsewhere, serving as a bridge that reconciles the conflicting requirements of weldability and corrosion resistance
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 prevents ferrite formation, maintaining the high strength and integrity of the weld zone, enhancing the mechanical properties and reliability of the tailor welded blanks by ensuring a martensite-rich microstructure, thus avoiding fractures and maintaining the component's intended function.
Implementation Method 1
heat-treating the plated steel sheet so that the aluminum-based plating layer becomes an Al-Fe-based intermetallic alloy layer
Implementation Method 2
the coating forms a surface alloy by mutual diffusion between steel and aluminum during heat treatment in a furnace
Implementation Method 3
laser beam welding has been used, advantageous in terms of process flexibility, quality, and productivity
Implementation Method 4
when austenite treatment (heating) is performed for the purpose of quenching the welded blank
Implementation Method 5
a use of a steel material having high mechanical strength by having martensite or bainite-martensite microstructure
Data Source
AI summary
An embodiment of the present invention provides a method for manufacturing a tailor welded blank using a steel sheet for hot pressing having an Al-Fe-based intermetallic alloy layer, the method comprising the steps of: preparing a plated steel sheet having a base steel sheet and an aluminum-based plated layer formed on one surface or both surfaces of the base steel sheet; heat-treating the plated steel sheet so that the aluminum-based plated layer becomes an Al-Fe-based intermetallic alloy layer; and subjecting the heat-treated plated steel sheet to butt welding, wherein, before the welding, a part or the entirety of the Al-Fe-based intermetallic alloy layer located in an area to be welded is removed.