Graded High-Strength Spring-Steels by a Special Inductive Heat T reatment

18th Chemnitz Seminar on Materials Engineering – 18. Werkstofftechnisches Kolloquium

Tump, A.^1,2 ; Brandt, R.^2

Mubea Fahrwerksfedern GmbH, Dr.-Karl-Heinz-Muhr-Straße, Weißensee

99631, Germany^1

Lehrstuhl für Werkstoffsysteme für Den Fahrzeugleichtbau, Universität Siegen - Fakultät IV, Am Eichenhang 50, Siegen

57076, Germany^2

关键词: Automotive component;    Comprehensive testing;    Corrosive environment;    Hardness gradient;    High specific strength;    Lightweight design;    Notch sensitivity;    Tailored materials;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/118/1/012021/pdf
DOI  :  10.1088/1757-899X/118/1/012021

来源: IOP

【 摘 要 】

A method for effective lightweight design is the use of materials with high specific strength. As materials e.g. titanium are very expensive, steel is still the most important material for manufacturing automotive components. Steel is cost efficient, easy to recycle and its tensile strength easily exceeds 2,000 MPa by means of modern QT-technology (Quenched and Tempered). Therefore, lightweight design is still feasible in spite of the high density of steel. However, a further increase of tensile strength is limited, especially due to an increasing notch sensitivity and exposure to a corrosive environment. One solution is a special QT-process for steel, which creates a hardness gradient from the surface to the core of the material. This type of tailored material possesses a softer layer, which improves material properties such as fracture toughness and notch sensitivity. This leads to a better resistance to stress corrosion cracking and corrosion fatigue. Due to this optimization, a weight reduction is feasible without the use of expensive alloying elements. To understand the damage mechanism a comprehensive testing procedure was performed on homogeneous and gradient steels. Some results regarding the fracture mechanic behavior of such steels will be discussed.