Nickel-Based Cladding Alloy for Cast Iron Repair
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Solution Overview
Problem
Existing cast iron repair alloys, such as those containing Inconel 690 with added lanthanum, face issues with hardness mismatch between the repair material and the base material, leading to potential brittleness and cracking due to carbide precipitation, and require additional heat treatment steps, which increase costs and complexity.
Innovation Solution
A nickel-based alloy with specific compositions of chromium, iron, silicon, boron, and carbon, ranging from 6.2% to 9.3% chromium, 3.0% to 4.5% iron, 1.4% to 2.15% silicon, 0.5% to 0.8% boron, and 0.1% carbon, is used for cladding, ensuring a hardness match with the base material and minimizing carbide precipitation, thus reducing the risk of cracking and eliminating the need for pre-heating and post-annealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Inconel 690 alloy with lanthanum is used for welding repair, then cracking of welded joints during cooling is prevented, but hardness mismatch between repair material and base material causes abrasion of repaired component or mating parts
Solution Approach 1:
The patent modifies the chemical composition parameters of the filler material by adding boron (0.05-1.0 wt%) and controlling carbon content (0.01-0.5 wt%), chromium (2.0-10.0 wt%), and other elements to adjust the hardness of the repaired area to match the base material, eliminating the hardness mismatch problem while maintaining crack prevention
2Reliability
If Inconel 690 alloy is used for welding repair, then welded joint integrity is improved, but carbide precipitation at the interface makes the interface brittle leading to further cracking
Solution Approach 1:
The patent controls carbon content (0.01-0.5 wt%) and adds boron (0.05-1.0 wt%) to modify the chemical parameters of the filler material, preventing carbide precipitation at the interface and eliminating interface brittleness while maintaining welded joint integrity
3Ease of repair
If conventional welding repair methods are used, then cracked portions can be repaired, but additional heat treatment is required after welding to relieve stresses
Solution Approach 1:
The filler material composition is designed to inherently relieve welding stresses without requiring external heat treatment processes, making the repair material itself perform the stress relief function that would otherwise require separate equipment and processes
4Reliability
If repair material with different hardness than base material is used, then crack prevention is achieved, but the repaired component or mating parts are abraded
Solution Approach 1:
The patent precisely controls the chemical composition parameters including boron (0.05-1.0 wt%), carbon (0.01-0.5 wt%), chromium (2.0-10.0 wt%), and other elements to achieve hardness matching between the repaired area and base material, eliminating abrasion while maintaining crack prevention capabilities
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 alloy achieves a Rockwell hardness comparable to the base material, reduces carbide formation, and eliminates interfacial cracks, enhancing the mechanical strength and fatigue life of repaired components while simplifying the repair process by reducing heat input and eliminating the need for additional heat treatment steps.
Implementation Method 1
The alloy may include on a weight basis, about 6.2% to about 9.3% of chromium (Cr), about 3.0% to about 4.5% of iron (Fe), about 1.4% to about 2.15% of silicon (Si), about 0.5% to about 0.8% of boron (B), about 0.1% of carbon (C), and a balance of nickel (Ni) and incidental impurities
Implementation Method 2
The disclosed alloy of the '446 patent may not prevent precipitation of carbides at the interface of the weld material and the base material of the component. Carbide precipitation may cause the interface between the weld material and the base material to become brittle
Implementation Method 3
Components welded using the method disclosed in the '446 patent may also require additional heat treatment after the welding process to relieve stresses in the component
Data Source
AI summary
An alloy for cladding cast iron is disclosed. The alloy may include on a weight basis, about 6.2% to about 9.3% of chromium (Cr), about 3.0% to about 4.5% of iron (Fe), about 1.4% to about 2.15% of silicon (Si), about 0.5% to about 0.8% of boron (B), about 0.1% of carbon (C), and a balance of nickel (Ni) and incidental impurities.