Ultra-High-Strength Valve Spring Steel Composition
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Solution Overview
Problem
Conventional engine valve springs made of CrSi or CrSiV steel lack the necessary tensile and fatigue strength required for improved fuel efficiency, as they have limited alloy composition optimization, leading to suboptimal performance in weight reduction and dynamic load management.
Innovation Solution
An ultra-high-strength spring steel composition is developed with optimized contents of Mo, Ni, V, Nb, Ti, B, and W, along with controlled inclusions, achieving a tensile strength of 3000 MPa or higher and fatigue strength of 1200 MPa or higher, suitable for engine valve springs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional CrSi or CrSiV steel compositions are used, then manufacturing simplicity is maintained, but tensile strength and fatigue strength are insufficient for improved fuel efficiency
Solution Approach 1:
The patent applies parameter changes by precisely controlling the chemical composition parameters of multiple alloying elements (C: 0.45-0.75%, Si: 1.00-2.50%, Mn: 0.50-1.50%, Cr: 0.50-1.50%, Mo: 0.10-0.60%, Ni: 0.05-0.80%, V: 0.05-0.50%, Nb: 0.05-0.50%, Ti: 0.05-0.30%, B: 0.001-0.010%, W: 0.01-0.50%). This systematic optimization of compositional parameters achieves ultra-high tensile strength (≥3000 MPa) and fatigue strength (≥1200 MPa) while maintaining manufacturing feasibility through established steelmaking processes
Solution Approach 2:
The patent creates a composite alloy system by combining multiple alloying elements (Cr, Si, V, Mo, Ni, Nb, Ti, B, W) in specific proportions. This multi-element composite composition synergistically enhances both tensile strength and fatigue strength, producing a steel material that exceeds the performance of conventional single-element or dual-element alloys while remaining compatible with existing manufacturing technologies
2Strength
If alloy element contents are increased to enhance strength, then tensile strength improves, but control of inclusions and manufacturing precision become more difficult
Solution Approach 1:
The patent converts the potentially harmful effect of alloying element additions (which can generate inclusions) into a beneficial outcome by carefully selecting and balancing the types and amounts of elements. The specific composition design promotes the formation of fine, dispersed inclusions that act as strengthening sites rather than defects, achieving tensile strength ≥3000 MPa while maintaining inclusion levels that satisfy manufacturing requirements
Solution Approach 2:
The patent employs precise parameter control by limiting the content of each alloying element to specific ranges and controlling impurity levels (P ≤ 0.030%, S ≤ 0.030%, O ≤ 0.005%). This systematic parameter optimization ensures that strength enhancement through alloying does not compromise manufacturing precision or inclusion control
3Use of energy by moving object
If weight reduction is implemented in valve springs to improve fuel efficiency, then fuel efficiency improves, but strength and reliability may be compromised
Solution Approach 1:
The patent achieves ultra-high strength (tensile strength ≥3000 MPa, fatigue strength ≥1200 MPa) through optimized compositional parameters, enabling significant weight reduction in valve springs while maintaining or improving reliability. The enhanced strength-to-weight ratio allows for lighter spring designs that meet or exceed performance requirements, directly contributing to improved fuel efficiency without sacrificing reliability
Solution Approach 2:
The patent develops a high-performance composite alloy system that provides exceptional strength and fatigue resistance, enabling weight reduction in valve springs. This advanced alloy composition allows manufacturers to design lighter springs with reduced cross-sectional areas while maintaining the necessary strength and reliability, thereby reducing dynamic load and improving fuel efficiency
Data Source
AI summary
An ultra-high-strength spring steel for an engine valve spring steel comprises, by weight: 0.5-0.7% of carbon (C), 1.3-2.3% of silicon (Si), 0.6-1.2% of manganese (Mn), 0.6-1.2% of chrome (Cr), 0.1-0.5% of molybdenum (Mo), 0.05-0.8% of nickel (Ni), 0.05-0.5% of vanadium (V), 0.05-0.5% of niobium (Nb), 0.05-0.3% of titanium (Ti), 0.001-0.01% of boron (B), 0.01-0.52% of tungsten (W), 0.3% or less (0% exclusive) of copper (Cu), 0.3% or less (0% exclusive) of aluminum (Al), 0.03% or less (0% exclusive) of nitrogen (N), 0.003% or less (0% exclusive) of oxygen (O), and a remainder of Fe and other inevitable impurities, based on 100% by weight of the ultra-high-strength spring steel.