Markus Härtel

Chemnitz University of Technology · Department of Mechanical Engineering

A well-known phenomenon in machinery systems is the easing of a blocked connection of mechanical parts after an impact hit close to the connection. Such impact hits may also arise in shaft–hub connections such as gears, crankshafts, or other parts. The objective of this study is to investigate the influence of local impact loads on the transmittabl...

Bauschinger effects typically describe a reduction of yield strength after a load path change under uniaxial loading conditions. Here, we use in-plane loading to investigate, for the first time, Bauschinger effects in the sheet metal DC06 under well-defined equi-biaxial loading conditions: We first performed equi-biaxial tensile tests with crucifor...

Over the last years heat treatment concept of "quenching and partitioning" (Q&P) has reached popularity for its ability to precisely adjust material properties to desired values. Mostly, Q&P process are applied on tailor-made materials with high purities or prototype alloys. The research in hand presents the whole routine of how to investigate the...

In order to achieve the desired properties, the microstructure of metals is often modified by heat treatments. A suitable combination of high strength and good ductility can be achieved by adjusting the amounts of martensite and retained austenite through a Quenching and Partitioning (Q&P) process. Controlling these material properties offers new p...

In many metallic materials, load path changes result in Bauschinger effects, i.e., a reduction of yield strength. In this study, we present results of a microstructural investigation on Bauschinger effects in the sheet metal DC06 subjected to in-plane uniaxial loading. We performed tension-compression tests with different values of maximum tensile...

Abstract: In this contribution, we study the microstructural evolution of an age hardenable AA6082 aluminum alloy during severe plastic deformation by gradation extrusion. A novel die design allowing an interruption of processing and nondestructive billet removal was developed. A systematic study on the microstructure gradient at different points o...

The Portevin–Le Châtelier (PLC) effect often results in serrated plastic flow during tensile testing of aluminum alloys. Its magnitude and characteristics are often sensitive to a material’s heat treatment condition and to the applied strain rate and deformation temperature. In this study, we analyze the plastic deformation behavior of an age-harde...

Biaxial tensile testing of sheet metals is becoming increasingly popular for sheet metal forming. Determining equivalent stresses in biaxial tensile specimens is more complicated than in conventional uniaxial tensile specimens. In the present study, we compare four different approaches to calculate effective stresses during biaxial tensile loading...

Recent work shows that severe plastic deformation processes such as ECAP or HPT considerably accelerate the precipitation kinetics of Al-Cu alloys. In this study, the authors analyze how a combination of mechanical load, aging time (and increased plastic strain), and aging temperature affects the precipitation kinetics of an AA2017 alloy after ECAP...

Severe plastic deformation methods are commonly used to increase the strength of materials by generating ultrafine-grained microstructures. The application of these methods to Al-Cu alloys is, however, difficult because of their poor formability at room temperature. An additional reduction of formability of such alloys occurs when ceramic particles...

Classically, the Bauschinger effect refers to a reduction of yield strength after a load path change. In this contribution, we present results of an experimental and microstructural investigation on Bauschinger effects in an AA1050 sheet metal (with 1 mm thickness) subjected to in-plane uniaxial loading. We performed tension-compression tests with...

An experimental analysis of the effect of in-plane strain path changes and Bauschinger effects during mechanical loading that involves compression is quite challenging for sheet materials because they are prone to buckling. In this paper, we present a newly developed method that allows to deform sheet metals in tension and in compression. Our exper...

The precipitation kinetics of Al-Cu alloys have recently been revisited in various studies, considering either the effect of severe plastic deformation (e.g., by equal-channel angular pressing – ECAP), or the effect of particle reinforcements. However, it is not clear how these effects interact when ECAP is performed on particle-reinforced alloys....