The requirements for steels applied in the automotive industry are manifold: strong steels are used for centre pillars, the part of a car installed next to the driver’s door. On the other hand, the front part of a car must consist of strong and at the same time ductile material.
Result of an analysis by the 3D-atom probe. The martensitic and austenitic phases are visible. Even single atoms are recognized by this technique – each dot represents the location of one atom while the surfaces are regions of iso-concentration of a certain element. Quelle: MPIE
Thus, in case of a crash, the shock energy can be absorbed and the driver is protected. Dr. Dirk Ponge, group leader at the MPIE, has achieved to combine both requirements in one class of new steel, named “lean maraging TRIP steels”. Due to a high nickel content conventional maraging steels are very strong and used in air plane landing gear. The term maraging merges ‘martensite’ and ‘aging’.
The name is derived from a special heat treatment (aging) which strengthens an already quite strong martensite structure. ”The use of a high amount of nickel results in a strong steel, but also caused an expensive production.” That’s why Ponge reduced the nickel content and found a surprising effect.
Combination of strength and ductility
During heat treatment, the formation of intermetallic precipitations causes an increase in strength. At the same time austenite is formed which is the reason for the increase in ductility and the basis for a second effect: the TRIP effect. TRIP stands for transformation induced plasticity. Triggered by a deformation process, a phase transformation from metastable austenite to martensite takes place in the material. This leads to an increase in strain hardening rate and enables to reach high elongations. With both these effects occurring, one obtains a good combination of tensile strength and total elongation up to 30.000 MPa%. The intermetallic precipitations, which are responsible for the excellent properties are analysed with the 3-dimensional atom probe.
Optimisation by computational materials design
Currently, the development of these steels is being optimised. Ponge expects to further decrease the production costs and to improve the mechanical properties by modifying the alloy composition. This is performed in close cooperation with the department of Computational Materials Design. The department of Prof. Jörg Neugebauer is calculating with the means of quantum physics, which precipitations are formed in the material with respect to the composition. This improves the efficiency of the further development and reduces the number of experiments. A systematic and application-oriented development of the lean high-performance steels is on the way.
Yasmin A. Salem, M.A.Public Relations
Yasmin A. Salem | MPIE
When your car knows how you feel
20.12.2017 | FZI Forschungszentrum Informatik am Karlsruher Institut für Technologie
Did you know how many parts of your car require infrared heat?
23.10.2017 | Heraeus Noblelight GmbH
A newly developed laser technology has enabled physicists in the Laboratory for Attosecond Physics (jointly run by LMU Munich and the Max Planck Institute of Quantum Optics) to generate attosecond bursts of high-energy photons of unprecedented intensity. This has made it possible to observe the interaction of multiple photons in a single such pulse with electrons in the inner orbital shell of an atom.
In order to observe the ultrafast electron motion in the inner shells of atoms with short light pulses, the pulses must not only be ultrashort, but very...
A group of researchers led by Andrea Cavalleri at the Max Planck Institute for Structure and Dynamics of Matter (MPSD) in Hamburg has demonstrated a new method enabling precise measurements of the interatomic forces that hold crystalline solids together. The paper Probing the Interatomic Potential of Solids by Strong-Field Nonlinear Phononics, published online in Nature, explains how a terahertz-frequency laser pulse can drive very large deformations of the crystal.
By measuring the highly unusual atomic trajectories under extreme electromagnetic transients, the MPSD group could reconstruct how rigid the atomic bonds are...
Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...
For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.
In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...
Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale
Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...
15.02.2018 | Event News
13.02.2018 | Event News
12.02.2018 | Event News
23.02.2018 | Physics and Astronomy
23.02.2018 | Health and Medicine
23.02.2018 | Physics and Astronomy