Strain-Hardened Nickel Alloy Welds for High-Strength Steel
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Solution Overview
Problem
Conventional ferrous-based weld metals used in steel structures lack sufficient strength, toughness, and integrity, particularly in high-strength steel applications, leading to issues like hydrogen cracking, tensile residual stress, and low fatigue resistance, which are exacerbated in offshore and deepwater structures where weight is critical.
Innovation Solution
The use of strain-hardened nickel-based alloy weld metals with compositions including greater than 10 wt% Mo, combined with other elements like W and Cr, to enhance weldment properties through solid solution strengthening and controlled cooling rates during fusion, friction stir, electron beam, or laser beam welding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional ferrous-based weld metals are used in high-strength steel structures, then the welding process is simple and cost-effective, but the weld strength, toughness, and fatigue resistance are insufficient
Solution Approach 1:
The patent changes the chemical composition parameters of the weld metal by using nickel as the primary base metal instead of ferrous-based alloys, and by controlling specific ranges of alloying elements (Mo: 5-20%, W: 2-10%, Cr: 5-15%, Mn: 2-10%, Ni: 3-12%). This parameter change transforms the weld metal's fundamental properties to achieve superior strength and toughness while maintaining controlled complexity through defined compositional ranges
Solution Approach 2:
The patent creates a composite weld metal system by combining nickel with multiple alloying elements (Mo, W, Cr, Mn, Ni) in specific proportions. This composite approach leverages the synergistic effects of different elements: nickel provides base strength and ductility, Mo and W contribute to solid solution strengthening and heat resistance, Cr enhances corrosion resistance, and Mn improves toughness. The resulting composite material achieves high strength and fatigue resistance that conventional ferrous-based weld metals cannot attain
2Reliability
If conventional ferrous-based weld metals are used, then the manufacturing process is straightforward, but hydrogen cracking and tensile residual stress occur
Solution Approach 1:
The patent changes the chemical composition parameters to nickel-based with controlled alloying elements, which fundamentally alters the weld metal's susceptibility to hydrogen cracking. The high nickel content combined with specific Mo, W, and Cr ranges creates a more resistant microstructure that prevents hydrogen embrittlement and reduces tensile residual stresses, thereby improving reliability without requiring complex additional manufacturing steps
Solution Approach 2:
The patent converts the potential harm of alloying element complexity into a benefit by strategically selecting elements that actively prevent hydrogen cracking and residual stress formation. The Mo, W, and Cr additions, while increasing compositional complexity, create a microstructure that is inherently more resistant to hydrogen embrittlement and thermal stress, thus improving weld integrity
3Strength
If conventional ferrous-based weld metals are used in offshore structures, then weight constraints are not addressed, but weld toughness and fatigue resistance are low
Solution Approach 1:
The patent changes the base metal parameter from ferrous to nickel-based, which provides a higher strength-to-weight ratio. The controlled alloying element ranges (Mo: 5-20%, W: 2-10%, Cr: 5-15%) further enhance toughness and fatigue resistance through solid solution strengthening, achieving superior mechanical properties that reduce the overall structural weight required for offshore applications
Solution Approach 2:
The patent applies local quality by concentrating specific alloying elements in the weld metal zone to achieve enhanced toughness and fatigue resistance where it is most needed. The high nickel content with controlled Mo, W, and Cr additions creates a localized region of superior mechanical properties in the weld metal, which directly addresses the toughness and fatigue resistance requirements for offshore structures without requiring increased overall structure weight
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 strain-hardened nickel-based alloy welds achieve superior mechanical properties such as increased fatigue strength, toughness, and strain capacity, providing an overmatched condition for high-strength steel joints, reducing residual stresses and hydrogen embrittlement, and enhancing weldment integrity.
Implementation Method 1
strain-hardened nickel-based alloy weld metals with compositions including greater than 10 wt% Mo, combined with other elements like W and Cr, to enhance weldment properties through solid solution strengthening and controlled cooling rates during fusion, friction stir, electron beam, or laser beam welding
Implementation Method 2
enhance weldment properties through solid solution strengthening and controlled cooling rates
Implementation Method 3
fusion, friction stir, electron beam, or laser beam welding
Data Source
AI summary
Provided are strain hardened high strength nickel based alloy welds that yield improved properties and performance in joining high strength metals. The advantageous weldments include two or more segments of ferrous or non-ferrous components, and fusion welds, friction stir welds, electron beam welds, laser beam welds, or a combination thereof bonding adjacent segments of the components together, wherein the welds comprise a strain hardened nickel based alloy weld metal composition including greater than or equal to 10 wt % Mo based on the total weight of the nickel based alloy weld metal composition. Also provided are methods for forming the welds from the nickel based alloy weld compositions. The strain hardened high strength nickel based alloy welds are useful in the oil, gas and petrochemical industry in applications for natural gas transportation and storage, oil and gas well completion and production, and oil and gas refinery and chemical plants.