Nickel-Based Alloy Inclusion Control for Superior Surface Quality
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Solution Overview
Problem
Existing methods for controlling non-metallic inclusions in Ni-based alloys containing more than 50 mass % of Ni are inadequate, leading to surface defects such as linear flaws, pitting, and reduced yield, which are not effectively addressed by previous patent documents.
Innovation Solution
Control the composition of non-metallic inclusions in Ni-based alloys by adjusting the concentrations of Si, Al, Mg, Ca, and O within specific ranges, and using a CaO—SiO2—MgO—Al2O3—F-based slag to refine the metal, followed by continuous casting and rolling processes, to minimize the formation of harmful inclusions that cause surface defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods for controlling non-metallic inclusions are applied to Ni-based alloys containing more than 50 mass % of Ni, then the general inclusion control approach is used, but surface defects such as linear flaws and pitting occur because the specific composition control for high-Ni alloys is insufficient
Solution Approach 1:
The patent applies parameter changes by establishing specific concentration ranges for Si (0.01 to 0.10 mass %), Al (0.001 to 0.170 mass %), Mg (0.0010 to 0.0200 mass %), Ca (0.0001 to 0.0040 mass %), and O (0.0001 to 0.0050 mass %) in high-Ni alloys. These precise parameter adjustments transform the inclusion control approach from generic to tailored for >50% Ni alloys, resolving the inadequacy of conventional methods and preventing surface defects like linear flaws and pitting
Solution Approach 2:
The patent segments the inclusion control strategy by specifically addressing high-Ni alloys (>50 mass % Ni) as a distinct category requiring separate composition parameters from lower-Ni alloys. This segmentation recognizes that Ni content greatly affects inclusion composition control, and applies dedicated compositional ranges for Si, Al, Mg, Ca, and O that are optimized specifically for the high-Ni regime, thereby improving surface quality where general methods fail
2Reliability
If Ni content is increased to more than 50 mass % for superior corrosion resistance and acid resistance, then corrosion performance is improved, but inclusion composition control becomes more difficult and surface defects increase
Solution Approach 1:
The patent resolves this contradiction by implementing specific parameter changes: limiting Si to 0.01-0.10 mass %, Al to 0.001-0.170 mass %, Mg to 0.0010-0.0200 mass %, Ca to 0.0001-0.0040 mass %, and O to 0.0001-0.0050 mass %. These tightened parameter controls are specifically designed for high-Ni alloys to manage the increased difficulty of inclusion composition control, thereby maintaining both superior corrosion resistance and high surface quality without the surface defects that typically accompany high-Ni processing
3Ease of manufacture
If trace quantities of Ca, Mg, Al, Si, and O are kept the same across different Ni contents, then compositional simplicity is maintained, but oxide-based non-metallic inclusion composition differs greatly and surface defects occur
Solution Approach 1:
The patent rejects compositional simplicity in favor of precision by establishing distinct parameter ranges for Si (0.01-0.10 mass %), Al (0.001-0.170 mass %), Mg (0.0010-0.0200 mass %), Ca (0.0001-0.0040 mass %), and O (0.0001-0.0050 mass %) specifically for high-Ni alloys. This recognizes that even trace quantities have amplified effects on oxide-based non-metallic inclusion composition when Ni content exceeds 50 mass %, and that tailored parameter control is necessary to prevent surface defects despite increased manufacturing complexity
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 effectively reduces the occurrence of surface defects and improves the cleanness and pitting corrosion resistance of Ni-based alloys, enhancing their suitability for severe corrosive environments.
Implementation Method 1
using a CaO—SiO2—MgO—Al2O3—F-based slag to refine the metal
Implementation Method 2
controlling the slag composition and Si, Al, Mg, Ca, and O in the molten metal, thereby controlling non-metallic inclusions in the molten metal to be harmless compositions
Implementation Method 3
controlling non-metallic inclusions in the molten metal to be harmless compositions, and further reducing the number of inclusions on the surface
Data Source
AI summary
A composition of non-metallic inclusions that affect surface properties and provides Ni-based alloys with superior surface properties. A Ni-based alloy consisting of: all by mass %, Ni: 52.0% or more, C: 0.001% to 0.030%, Si: 0.01 to 0.10%, Mn: 0.10 to 1.50%, P: 0.030% or less, S: 0.0050% or less, Cr: 13.0 to 25.0%, Mo: 10.0 to 18.0%, W: 1.00 to 5.00%, Cu: 1.00% or less, Co: 3.00% or less, Al: 0.001 to 0.170%, Fe: 2.00 to 8.00%, Mg: 0.0010 to 0.0200%, Ca: 0.0001 to 0.0040%, V: 0.500% or less, Nb: 0.001 to 0.100%, O: 0.0001 to 0.0050%, wherein the non-metallic inclusions includes one or more of MgO, CaO, CaO—MgO-based oxides, CaO—Al2O3—MgO-based oxides, and MgO.Al2O3, the MgO.Al2O3 has number ratio of 50% or less with all oxide-based non-metallic inclusions.