High Strength Low Alloy Steel Composition for Automotive Weight Reduction
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Solution Overview
Problem
The automotive industry faces challenges in achieving energy savings and safety through weight reduction, where existing high strength steels do not adequately balance strength, weldability, and cost-effectiveness for structural and safety components.
Innovation Solution
A new generation of high strength low alloy steel with specific compositions and manufacturing processes, including quenched and tempered fine-grained microstructure, optimized alloying elements, and heat treatment methods, to achieve enhanced mechanical properties and deep hardenability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional high strength steels are used to achieve weight reduction, then strength is improved, but weldability and cost-effectiveness deteriorate
Solution Approach 1:
The patent applies parameter changes by precisely controlling the chemical composition parameters of the steel alloy, specifically limiting nickel to 1.0% maximum, molybdenum and tungsten sum to 0.20% maximum, vanadium to 0.30% maximum, and titanium and niobium sum to 0.10% maximum. These compositional parameter changes enable achieving high strength (215-340 ksi tensile strength) while maintaining weldability and cost-effectiveness, resolving the contradiction between strength improvement and manufacturing ease.
2Strength
If conventional high strength steels are used to achieve weight reduction, then strength is improved, but cost-effectiveness deteriorates
Solution Approach 1:
The patent implements parameter changes by optimizing the alloy composition to use lower concentrations of expensive elements. Specifically, nickel is limited to 1.0% maximum, molybdenum and tungsten combined to 0.20% maximum, and vanadium to 0.30% maximum. This compositional optimization achieves the required strength range (215-340 ksi) while reducing material costs, thereby improving cost-effectiveness without sacrificing strength.
3Weight of moving object
If existing high strength steels are used for structural components, then weight reduction is achieved, but the balance between strength, weldability, and cost is insufficient
Solution Approach 1:
The patent resolves the reliability issue by making comprehensive parameter changes in the steel composition. The specific constraints on alloying elements (nickel ≤1.0%, Mo+W ≤0.20%, V ≤0.30%, Ti+Nb ≤0.10%) create a balanced material that simultaneously achieves weight reduction through high strength, maintains weldability through controlled composition, and ensures cost-effectiveness through reduced alloy content. This multi-parameter optimization creates a reliable balance among all three factors.
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 new steel achieves tensile strengths of 110 ksi to 340 ksi, elongation of 20% to 30%, and Charpy impact toughness of 30 ft-lb to 40 ft-lb, making it suitable for automotive structural, safety, power-train, and suspension components while offering weight reduction benefits.
Implementation Method 1
quenched and tempered, fine-grained, with deep hardenability, high strength and low alloy steel
Implementation Method 2
The first embodiment of the New Steel is a low alloy composition having in weight percentage nickel of 1.0% maximum, a sum of molybdenum and tungsten of 0.20% maximum, vanadium of 0.30% maximum, and a sum of titanium and niobium of 0.10% maximum
Data Source
AI summary
The present invention relates to a wrought, quenched and tempered, fine-grained, with deep hardenability, high strength and low alloy steel having a sum of the alloying elements: nickel, molybdenum, tungsten, vanadium, titanium, and niobium in weight percent 1.0% to 1.60%. The air melted and hot forged steel of the present invention has hardness of HRC 55, an ultimate tensile strength of 300 ksi, a yield strength of 257 ksi, a total elongation of 9%, a reduction of area of 32%, and Charpy v-notch impact toughness energy of 15 ft-lb after normalizing, gas quenching, and tempering at 450° F.