Resistance-Welded Steel Joints Tempered to Prevent Quench Cracks
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Solution Overview
Problem
Welding high-carbon steel materials, such as quenched carburized steel, often results in brittle welded portions prone to cracking due to the formation of a hard and brittle quenched structure during the welding process.
Innovation Solution
A method involving resistance welding with simultaneous pressure application, followed by electromagnetic heating using induction heating coils to temper the welded joint, ensuring the joint is heated differently on opposing edges to prevent cracking, allowing for increased flexibility in the welding process and improved productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If resistance welding is performed on high-carbon steel materials, then welding speed and productivity are improved, but the welded portions become hard and brittle and prone to cracking
Solution Approach 1:
The patent applies preliminary tempering treatment to the high-carbon steel members before resistance welding. This pre-treatment modifies the material structure in advance to prevent the formation of hard and brittle quenched structures during welding, thereby preventing cracks while maintaining high welding speed and productivity.
Solution Approach 2:
The patent changes the thermal parameter by applying tempering heat treatment before welding. This parameter change transforms the material's thermal history and microstructure, making it resistant to quenching during the welding process, thus resolving the contradiction between welding speed and crack resistance.
2Reliability
If electromagnetic heating is applied after welding, then tempering of the welded portion is achieved and crack occurrence is inhibited, but the manufacturing process becomes more complex
Solution Approach 1:
The patent combines the tempering treatment and welding operations into a single integrated manufacturing process. By applying tempering before welding and maintaining it throughout, the process achieves crack inhibition without requiring separate post-welding tempering equipment or steps, thus avoiding increased device complexity.
Solution Approach 2:
The patent maintains continuous tempering heat treatment throughout the welding process. This continuous application of tempering ensures that the material remains in a non-prone-to-cracking state throughout welding, eliminating the need for separate discrete tempering steps and reducing overall process complexity.
3Reliability
If the entire joint surface is tempered uniformly, then crack resistance is improved, but the flexibility in positioning heating equipment is reduced
Solution Approach 1:
The patent applies tempering treatment locally to the joint surface regions that require crack resistance, rather than uniformly treating the entire member. This localized approach allows flexible positioning of heating equipment only where needed at the joint, maintaining equipment positioning flexibility while achieving sufficient crack resistance at the critical welded portions.
Solution Approach 2:
The patent varies the tempering parameters (such as temperature and duration) across different regions of the joint surface based on local requirements. This parameter variation allows the use of flexible heating equipment positioned at different locations, achieving adequate crack resistance without requiring uniform treatment of the entire surface.
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 effectively inhibits the occurrence of cracks in welded joints by tempering the quenched portions, reducing the hardness of the welded area to a suitable level, thereby enhancing the durability and reliability of the joined member without the need for pre-treating the carburized layer.
Implementation Method 1
electromagnetic heating using induction heating coils to temper the welded joint
Implementation Method 2
electromagnetic heating step of tempering a portion where the first member D and the second member E have been welded to each other by electromagnetic heating
Implementation Method 3
welding the joint target portions of the first member D and the second member E by heating
Data Source
AI summary
To provide a method and apparatus for manufacturing a joined member that inhibit occurrence of cracks in a joined member even when the joined portion is quenched when members are welded together. The method includes placing the first member D and the second member E with a joint target portion Df and a joint target portion Ef being in contact with each other, welding the joint target portions by heating, subjecting the first member D after the welding to a process for inhibiting occurrence of cracks, and tempering a portion where the first and second members have been welded to each other by electromagnetic heating. The apparatus includes a first electrode 11 to contact with the first member D; a second electrode 12 to contact with the second member E; and an induction heating coil 23 for performing induction heating of a portion where a joint target portions Df and Ef have been contacted and joined to each other, and the induction heating coil 23 is placed between the two electrodes 11 and 12 when the induction heating is performed.