Solid-State Welding of Nitinol-Stainless Joints Under Staged Force
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Solution Overview
Problem
Existing methods struggle to directly weld dissimilar metallic materials, such as nitinol and stainless steel, together in a solid state without melting, leading to inconsistent weld integrity and unpredictable failure due to metallurgical incompatibilities.
Innovation Solution
A method involving the application of a first force during electrical current delivery followed by a greater follow-up force after deformation to form a weld nugget, ensuring solid-state deformation without melting, resulting in a thinner and larger cross-sectional area weld joint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrical current is delivered through dissimilar metallic materials to weld them in solid state, then the materials are heated and undergo solid state deformation to form a weld joint, but the weld integrity becomes inconsistent and unpredictable due to metallurgical incompatibilities
Solution Approach 1:
The method applies a preliminary force to the dissimilar metallic materials before delivering electrical current, pre-positioning the materials in optimal alignment. This preliminary action ensures consistent contact and deformation patterns during welding, eliminating variability caused by misalignment and resulting in uniform weld integrity across all joints.
Solution Approach 2:
The invention changes the parameters of the welding process by applying controlled mechanical force in conjunction with electrical current. By adjusting the magnitude and timing of the applied force relative to the electrical current delivery, the method achieves consistent solid state deformation and weld formation despite metallurgical incompatibilities between dissimilar materials.
2Manufacturing precision
If a follow-up force greater than the first force is applied after deformation occurs, then the weld nugget becomes thinner and of larger transverse cross-sectional area, but the process complexity increases
Solution Approach 1:
The welding process employs periodic action by applying force in distinct stages: an initial force during current delivery, followed by a greater follow-up force after deformation begins. This staged, periodic application of force creates consistent weld nugget dimensions with controlled thickness and enlarged transverse cross-sectional area, while the systematic nature of the periodic action keeps process complexity manageable.
3Strength
If electrical current is used to heat materials for solid state welding, then the materials deform and form weld joints without melting, but dissimilar materials with metallurgical incompatibilities produce unpredictable weld strength
Solution Approach 1:
The method incorporates feedback by monitoring the deformation response of the dissimilar materials during welding and adjusting the applied force accordingly. The follow-up force is specifically tuned based on the observed deformation characteristics, ensuring that weld strength reaches optimal levels while compensating for metallurgical incompatibilities between the dissimilar materials.
Solution Approach 2:
The invention effectively creates a composite weld structure by joining dissimilar metallic materials through controlled solid state deformation. The process produces a weld nugget that combines the properties of both materials with a thinner profile and larger transverse cross-sectional area, achieving predictable and reliable weld strength despite the metallurgical incompatibilities of the constituent materials.
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 method achieves consistent weld strength and reduced variability, enabling reliable joining of dissimilar metals with improved kink resistance and increased durability.
Implementation Method 1
the applied electrical (e.g., DC, AC, or both) current serves to heat the portions of the members to be joined so that they undergo solid state deformation, such that the materials are not melted
Implementation Method 2
delivering electrical (e.g., DC, AC, or both) current through the separate members so as to weld the separate portions to one another
Data Source
AI summary
The present disclosure is directed to a multi-segment device comprising an elongate first portion comprising a first metallic material, an elongate second portion comprising a different metallic material, the first and second elongate portions being directly joined together end to end, a heat affected zone surrounding an interface of the elongate first portion and the elongate second portion, a shapeable distal end formed from at least a portion of the elongate second portion, a coil disposed about a portion of the elongate second portion.