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Correlation between dynamic material behavior and adiabatic shear phenomenon for quenched and tempered steels

Pursche F., Meyer L. W.

Engineering Transactions

2011

Vol. 59, iss. 3

67-84

Besides the common failure mechanism based on crack propagation, adiabatic shear failure results from a collapse mechanism, mainly at high deformation rates. This failure incorporates locally extreme high shear strains, but due to the small volume involved, it transpires in macroscopic brittle manner. This paper deals with the description of the influence of material properties on adiabatic shear failure. In the literature, much information can be found, which supports the theory that some material properties in?uence the occurrence of adiabatic shear failure behavior in a positive or negative manner. The determination of propensity for the investigated steels was done through special biaxial dynamic compression-shear-test in a drop weight tower. The failure achieved in the test is only material-dependent. Furthermore, it was found, that the theory of Culver with the competing processes of work hardening and thermal softening is transferable on the tested materials in a qualitative manner. Additionally, it was determined that few material properties have a strong controlling e?ect on the adiabatic shear failure behavior and it is possible to determine a critical value for transition between sheared and non sheared areas. Moreover, it could define a functional correlation of the failed materials to certain properties. As a main result, the most important material property is the dynamic compression behavior at high temperature. The stress level of the material and the characteristic in dependence of temperature is decisive. Analytical considerations using high temperature behavior patterns confirm this influence. Additionally, hardness and strength at room temperature and the pure shear capability (hat-shaped specimen) are also important for the evaluation of adiabatic failure behavior.

Material behavior under dynamic mono- and biaxial loading

Meyer L. W., Herzig N., Pursche F., Abdel-Malek S.

Engineering Transactions

2010

Vol. 58, iss. 3/4

119-129

This paper gives an overview of different testing methods and the mechanical material behavior including mono-axial and multi-axial testing under high rate loading. Special emphasis is laid on difficult loading conditions and loading states such as a high temperature and high strain loading (? > 1200?C, ? > 1) and multiaxial impact tests. The impact behavior of selected materials is shown and compared for di?erent loading conditions. Furthermore, a distinction is made between virgin and manufactured material behavior (e.g. welding) or pre-damaged materials. Specifically, if the influence of the manufacturing history is investigated. Under certain loading states the impact material properties show a dramatic difference compared to the virgin state of the material. Some examples of different material behavior under the conditions previously mentioned are given.