Cu-Ni-Sn Alloy Microstructure for Strength and Bending Workability
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Solution Overview
Problem
Existing copper alloys lack an appropriate organizational structure, resulting in insufficient strength and bending workability, particularly after aging treatment, as they do not consider crystal orientation and often have large crystal grains that hinder bending workability.
Innovation Solution
A copper alloy with a composition of 8.5 to 9.5 mass % Ni, 5.5 to 6.5 mass % Sn, and the remainder Cu, featuring an average crystal grain diameter of less than 6 μm, a specific crystal grain ratio, and controlled X-ray diffracted intensity ratios, along with controlled surface roughness and inclusion distribution, to achieve high strength and excellent bending workability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional Cu-Ni-Sn-based alloys are used with standard composition ranges, then the alloy can provide high strength through aging treatment, but bending workability is insufficient due to large crystal grain size and lack of crystal orientation control
Solution Approach 1:
The invention changes the composition parameters to a narrow optimal range (Ni: 8.5-9.5 mass%, Sn: 5.5-6.5 mass%) and introduces new control parameters for crystal grain size (<6 μm) and crystal orientation (XRD intensity ratios). This precise parameter control enables both high strength and excellent bending workability by optimizing the balance between strength mechanisms and ductility.
Solution Approach 2:
The invention creates a composite microstructure consisting of fine crystal grains with specific orientation distribution and a modulation structure formed through aging treatment. This multi-scale composite structure combines the strength benefits of fine grains and precipitation hardening with the ductility benefits of favorable crystal orientation, resolving the contradiction between strength and bending workability.
2Ease of operation
If crystal grain size is reduced to improve bending workability, then bending workability improves, but strength may be compromised without proper composition and orientation control
Solution Approach 1:
The invention optimizes composition parameters (Ni: 8.5-9.5 mass%, Sn: 5.5-6.5 mass%) to work synergistically with fine crystal grain size (<6 μm). This coordinated parameter change ensures that the fine grain structure provides both improved bending workability and enhanced strength through grain boundary strengthening, rather than compromising strength.
Solution Approach 2:
The invention creates a composite microstructure where fine crystal grains are combined with a modulation structure formed through aging treatment. This multi-scale composite provides dual benefits: fine grains improve bending workability while the precipitation hardening from the modulation structure maintains high strength, eliminating the trade-off between these properties.
3Strength
If Ni and Sn content is increased to improve strength, then strength increases, but bending workability deteriorates due to larger crystal grain formation
Solution Approach 1:
The invention narrows the composition range to optimal values (Ni: 8.5-9.5 mass%, Sn: 5.5-6.5 mass%) that prevent excessive crystal grain growth during processing. This precise parameter control allows the alloy to achieve high strength through precipitation hardening rather than grain growth, thereby maintaining both strength and bending workability.
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 simultaneous high strength and excellent bending workability by optimizing crystal grain size, orientation, and surface characteristics, ensuring stable performance in both tensile and bending tests.
Implementation Method 1
a modulation structure is formed through aging treatment
Implementation Method 2
a modulation structure is formed through aging treatment, and as a result, the Cu—Ni—Sn-based alloy is known to be an alloy that provides high strength
Implementation Method 3
an X-ray diffracted intensity ratio in a plate surface parallel to the rolling direction of the copper alloy includes, when an X-ray diffracted intensity of a (220) plane is standardized as 1
Implementation Method 4
an X-ray diffracted intensity ratio in a plate surface parallel to the rolling direction of the copper alloy includes, when an X-ray diffracted intensity of a (220) plane is standardized as 1, an intensity ratio of a (200) plane being 0.30 or less
Data Source
AI summary
A copper alloy according to the present invention is a copper alloy rolled to be plate-shaped. The copper alloy contains 8.5 to 9.5 mass % of Ni, 5.5 to 6.5 mass % of Sn with a remainder being Cu and unavoidable impurities. An average diameter of crystal grains in a cross section perpendicular to a rolling direction is less than 6 μm. A ratio x/y of an average length x of the crystal grains in a plate width direction to an average length y in a plate thickness direction satisfies 1≤x/y≤2.5. An X-ray diffracted intensity ratio in a plate surface parallel to the rolling direction of the copper alloy includes, when an X-ray diffracted intensity of a (220) plane is standardized as 1, an intensity ratio of a (200) plane being 0.30 or less, an intensity ratio of a (111) plane being 0.45 or less, and an intensity ratio of a (311) plane being 0.60 or less. The intensity ratio of the (111) plane is greater than the intensity ratio of the (200) plane and smaller than the intensity ratio of the (311) plane.