Austenitic Stainless Steel Watch Spring Alloy Design
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Solution Overview
Problem
Current watch springs face challenges in achieving high fatigue resistance and power reserve due to materials' sensitivity to corrosion and permanent deformation, with high-nitrogen stainless steel alloys being difficult to produce and expensive, and existing solutions failing to provide effective alternatives for small-scale horological applications.
Innovation Solution
A stainless steel alloy with a low nitrogen content and added carbon, comprising 15-25% chromium, 5-25% manganese, 0.10-0.90% nitrogen, and 0.10-1.00% carbon, optimized for improved ductility and mechanical properties, allowing for the production of springs with small dimensions and high curvature radii, reducing production costs and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-nitrogen stainless steel alloy is used to improve fatigue resistance and mechanical properties, then the spring durability and elasticity are enhanced, but the ductility is reduced and the manufacturing becomes difficult and expensive
Solution Approach 1:
The patent applies parameter changes by precisely controlling the nitrogen content (0.03-0.10% by weight) and carbon content (0.003-0.03% by weight) within specific ranges, along with adding manganese (1.0-2.0% by weight) and controlling chromium content (13.0-20.0% by weight). This optimization of compositional parameters achieves the desired balance between fatigue resistance and ductility, making the alloy easier to manufacture while maintaining high reliability
Solution Approach 2:
The patent creates a composite material system by combining multiple alloying elements (chromium, manganese, nitrogen, carbon) in specific proportions to form an austenitic stainless steel with enhanced properties. The synergistic interaction between these elements produces a material that simultaneously achieves high fatigue resistance, adequate ductility, and improved manufacturability
2Strength
If high-nitrogen stainless steel alloy is used to improve mechanical properties, then the spring strength is enhanced, but the cost of production increases
Solution Approach 1:
The patent reduces production cost by optimizing the nitrogen content to a lower range (0.03-0.10% by weight) compared to conventional high-nitrogen alloys, while compensating for mechanical properties through controlled carbon content (0.003-0.03% by weight) and manganese addition (1.0-2.0% by weight). This parameter optimization maintains spring strength while reducing material and processing costs
3Strength
If high-nitrogen stainless steel alloy is used to improve elasticity, then the power reserve is enhanced, but the ductility is reduced
Solution Approach 1:
The patent resolves the ductility-elasticity contradiction by precisely controlling the nitrogen content (0.03-0.10% by weight) to prevent excessive brittleness while maintaining elasticity, and by adding manganese (1.0-2.0% by weight) which enhances both ductility and elastic properties. The controlled carbon content (0.003-0.03% by weight) further contributes to achieving the desired balance between these properties
4Duration of action of stationary object
If high-nitrogen stainless steel alloy is used to improve fatigue resistance, then the service life is extended, but the manufacturing precision becomes difficult to control
Solution Approach 1:
The patent improves manufacturing precision by controlling nitrogen content within a moderate range (0.03-0.10% by weight) rather than using very high nitrogen levels, which makes the alloy less sensitive to processing parameters. The addition of manganese (1.0-2.0% by weight) and controlled carbon content (0.003-0.03% by weight) further stabilizes the material properties during manufacturing, enabling better dimensional control while maintaining extended service life through improved fatigue resistance
Data Source
Figure 1
Figure 2~3
AI summary
Watchmaking spring (1) made of austenitic stainless steel alloy having a base of iron and chromium. Its thickness is less than 0.20 mm. It comprises by mass: - chromium: minimum value 15%, maximum value 25%; - manganese: minimum value 5%, maximum value 25%; - nitrogen: minimum value 0.10%, maximum value 0.90%; - carbon: minimum value 0.10%, maximum value 1.00%; - the total mass content of carbon and nitrogen in proportion to the total between 0.40% and 1.50%; - the (C/N) ratio of the mass content of carbon in proportion to that of nitrogen in proportion to the total between 0.125 and 0.550; - impurities and filler metals except iron: minimum value 0%, maximum value 12.0%; - iron: the remainder to 100%. Application to a barrel spring.