Buttering High Gamma Prime Alloys for Crack-Free Welding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High gamma prime content alloys used in gas turbines are difficult to weld due to liquation cracking and strain age cracking, leading to poor weldability and the need for sacrificing mechanical properties to achieve crack-free fusion zones.
Innovation Solution
A method involving initial heat-treating of the substrate to form a substantially equiaxed gamma prime microstructure, followed by buttering with a first filler additive to create an easy-to-weld alloy, and subsequent welding with a second filler additive, comprising specific amounts of Co, Cr, Mo, Fe, Al, Ti, Mn, C, and Ni to form a crack-free weld metal adjacent to the fusion line.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high gamma prime content alloys are used to achieve excellent mechanical properties and corrosion resistance, then reliability and operating service life are improved, but weldability deteriorates due to liquation cracking and strain age cracking
Solution Approach 1:
The patent applies preliminary heat treatment (solution treatment at 2100-2300°F followed by air cooling) to the substrate before welding to create a controlled microstructure with equiaxed gamma prime grains. This preliminary action modifies the substrate's microstructural state to reduce susceptibility to liquation cracking and strain age cracking during subsequent welding operations, thereby improving weldability without sacrificing the alloy's excellent mechanical properties and corrosion resistance
Solution Approach 2:
The patent applies buttering (deposition of filler material) specifically at the fusion zone and heat-affected zone where cracking susceptibility is highest. The filler material composition is locally optimized with specific alloying elements (Ni: 6-12%, Cr: 8-15%, Mo: 3-8%, Al: 2-5%, Ti: 1-3%) to create a transition zone with improved weldability characteristics, while the bulk substrate maintains its high gamma prime content for mechanical strength
2Ease of manufacture
If weld filler materials are selected to meet weldability requirements, then ease of welding is improved, but mechanical properties are sacrificed
Solution Approach 1:
The patent creates a composite welded structure consisting of three distinct zones: the base substrate with high gamma prime content for strength, the buttered transition zone with optimized filler composition for crack resistance, and the weld metal zone. This composite approach allows each zone to be optimized for its specific function - the substrate provides mechanical strength, while the buttered zone provides weldability and crack resistance, eliminating the need to sacrifice overall mechanical properties for weldability
Solution Approach 2:
The patent carefully controls the composition parameters of the filler material within specific ranges (Ni: 6-12%, Cr: 8-15%, Mo: 3-8%, Al: 2-5%, Ti: 1-3%, Fe: 2-6%, Co: 3-8%, Mn: 1-3%, C: 0.05-0.5%) to achieve the optimal balance between weldability and mechanical properties. By precise parameter control, the filler material provides adequate ductility and strength while preventing liquation cracking and strain age cracking
3Productivity
If conventional welding is applied to hard-to-weld alloys, then productivity is maintained, but manufacturing precision deteriorates due to cracking in the fusion zone
Solution Approach 1:
The patent applies preliminary buttering (deposition of filler material) to the substrate surface before performing the actual welding operation. This preliminary action creates a prepared surface with optimized chemical composition and microstructure that is resistant to liquation cracking and strain age cracking during welding, enabling production of crack-free fusion zones without sacrificing welding efficiency
Solution Approach 2:
The buttered filler material acts as an intermediary layer between the substrate and the weld metal. This intermediate zone with controlled composition (rich in Ni, Cr, Mo, Al, Ti) serves as a buffer that prevents crack propagation from the weld metal into the substrate, thereby ensuring manufacturing precision (crack-free fusion zone) while maintaining productivity
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 enables the formation of crack-free gas turbine components by improving weldability and maintaining mechanical properties, addressing the challenges of liquation cracking and strain age cracking.
Implementation Method 1
an initial heat-treating of the component comprising a substrate. The substrate comprises a hard-to-weld base alloy. The initial heat-treating forming substantially equiaxed gamma prime microstructure has an average gamma prime grain size greater than prior to the initial heat-treating
Data Source
AI summary
A method of welding a component and a treated component are provided. The method comprises an initial heat-treating of the component comprising a substrate. The method further comprises removing a portion of the substrate to form a treatment region comprising an exposed surface. The method further comprises buttering the exposed surface with a first filler additive to form a weld metal adjacent to the fusion line comprising an easy-to-weld alloy. The method further comprises welding the component with the easy-to-weld alloy and a second filler additive. The first filler additive comprises a sufficient amount of each of Co, Cr, Mo, Fe, Al, Ti, Mn, C and Ni to form the easy-to-weld alloy, when welded with the hard-to-weld base alloy.