Temper-Resistant Steel Alloy for Chassis Heat-Affected Zones
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Solution Overview
Problem
Motor vehicle chassis and drive components face challenges in withstanding mechanical loads and thermal stress, particularly in the heat-affected zones, where tempering of materials occurs, affecting their properties and weldability.
Innovation Solution
A temper-resistant steel alloy with specific compositions of carbon, manganese, chromium, silicon, vanadium, boron, titanium, and optionally molybdenum is used to enhance mechanical characteristics, ensuring high yield and tensile strength, air-hardening properties, and improved weldability, reducing the need for additional alloying elements and heat treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If carbon content is increased to improve strength, then yield strength and tensile strength increase, but weldability deteriorates
Solution Approach 1:
The patent optimizes the carbon content parameter to a specific range (0.17-0.25%) to achieve the desired balance between strength and weldability. This parameter optimization allows the material to attain sufficient mechanical properties while maintaining manufacturability through welding operations.
Solution Approach 2:
The patent creates a composite alloy system by combining carbon with multiple alloying elements (manganese, silicon, chromium, vanadium, boron, titanium, and optionally molybdenum) in specific proportions. This composite material approach allows the synergistic effects of different elements to enhance strength while mitigating the negative impact of carbon on weldability.
2Strength
If alloying elements are added to increase strength, then mechanical properties improve, but material cost increases
Solution Approach 1:
The patent specifies precise parameter ranges for each alloying element to optimize the strength-to-cost ratio. By defining narrow compositional windows, the patent achieves the required mechanical properties with minimal necessary amounts of expensive alloying elements, avoiding unnecessary cost increases.
Solution Approach 2:
The patent applies different alloying strategies to different functional requirements: carbon and manganese provide baseline strength and hardenability, while smaller amounts of vanadium, boron, and titanium provide targeted microstructural control and temper resistance. This localized approach to alloying ensures each element contributes efficiently to specific property goals.
3Ease of manufacture
If thermal processing is applied to join components, then welding is achieved, but tempering occurs in the heat-affected zone reducing material properties
Solution Approach 1:
The patent converts the harmful effect of heat exposure during welding into a beneficial outcome by designing the alloy composition to develop superior mechanical properties through controlled tempering in the heat-affected zone. The specific alloying elements promote formation of tempered martensite or bainite structures that provide high strength and toughness after welding thermal cycles.
Solution Approach 2:
The patent modifies the material's chemical composition parameters to include elements that stabilize desired microstructures during thermal processing. The combination of manganese, silicon, chromium, and vanadium creates a compositional state that promotes formation of strong, ductile microstructures in the heat-affected zone after welding, transforming the thermal process from harmful to beneficial.
4Weight of moving object
If wall thickness is reduced to decrease weight, then weight reduction is achieved, but load-bearing capacity may be compromised
Solution Approach 1:
The patent employs a composite steel alloy containing multiple elements in specific proportions that work synergistically to achieve high strength-to-weight ratio. The combination of carbon, manganese, silicon, chromium, vanadium, boron, and titanium creates a material with superior mechanical properties that enables weight reduction while maintaining load-bearing capacity.
Solution Approach 2:
The patent optimizes the compositional parameters of the alloy to achieve a microstructure with enhanced strength characteristics. By controlling the content of each alloying element within specific ranges, the material develops a microstructure that provides high yield strength and tensile strength, enabling thinner-walled components to carry the same loads.
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 provides high yield and tensile strengths in the heat-affected zones, preventing component failure under dynamic loads, allowing for reduced wall thickness and potential weight reduction without compromising load-bearing capacity, while maintaining sufficient hardness and weldability.
Implementation Method 1
the material used according to the invention is an air-hardening material
Implementation Method 2
manganese contributes to the increase of strength by solid solution strengthening
Implementation Method 3
In particular in the area of thermal stress, which is also referred to as heat-affected zone, tempering of the material of the component may occur
Data Source
AI summary
The present invention relates to a, comprising a tubular element (10) with at least one heat-affected zone (14), characterized by a yield strength Rp0.2 in the heat-affected zone (14) of at least 640 MPa and a tensile strength Rm in the heat-affected zone of at least 850 MPa and by at least the tubular element (10) consisting of a steel alloy consisting, in weight percent:C0.12-0.22%Mn1.5-2.5%Si0.45-0.85%Cr <1.5%V≥0.04%B0.0010-0.0040%Ti 0.02-0.1% undoptionally Mo ≤0.6%,balance iron and impurities resulting from smelting.