Laser-induced softening analysis of a hardened aluminum alloy by physical simulation
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ORIGINAL ARTICLE
Laser-induced softening analysis of a hardened aluminum alloy by physical simulation Maria Emanuela Palmieri 1 & Vincenzo Domenico Lorusso 1 & Luigi Tricarico 1 Received: 16 January 2020 / Accepted: 5 October 2020 / Published online: 14 October 2020 # The Author(s) 2020
Abstract The study focuses on the analysis of the softening effects of the work-hardened aluminum alloy sheets EN AW 5754 H32 1.5 mm thick, through the physical simulation of thermal cycles induced in the material by laser heat treatments (LHTs). A numericalexperimental approach was implemented to define the laser thermal cycles and to subsequently reproduce them on the GleebleTM 3180 physical simulator. The obtained softening was measured by microhardness and metallographic analysis tests. For the definition of laser thermal cycles, preliminary tests with a 2.5 kW CO2 laser source have been realized, and a three-dimensional transient finite element thermal models were developed and calibrated with the experimental results. The investigated laser heat treatment parameters explored thermal cycles with different shape, interaction time, and peak temperature. Physical simulation tests were performed using laser thermal cycles that showed the maximum softening of the aluminum alloy. A three-dimensional transient finite element thermoelectric model was developed to design the shape of the Gleeble specimens, which satisfy the heating and cooling rate required by laser thermal cycles. Results obtained show that it is possible to physically simulate the investigated laser thermal cycles, reducing the cross section of the shaped part of the specimen. Softening effects depend on the thermal cycle shape. Greater softening is observed by increasing the interaction time and the peak temperature, but beyond a peak temperature threshold value, negligible effects are detected. Keywords Laser methods . Aluminum alloys . Physical simulation . Finite element analysis . Hardness
1 Introduction Interest in the local softening using laser heat treatment process is growing in recent period because it offers the possibility to process metal alloy sheets locally, creating areas with defined mechanical properties. This treatment is increasingly used in the local softening of high-strength steel sheet parts facilitating riveting phase in the treated areas [1] or in the local softening of high-strength aluminum alloys (work hardened or age hardenable) [2, 3], improving their formability before
* Maria Emanuela Palmieri [email protected] Vincenzo Domenico Lorusso [email protected] Luigi Tricarico [email protected] 1
Dipartimento di Meccanica, Matematica e Management, Politecnico di Bari, Via E. Orabona 4, 70125 Bari, Italy
forming. In this latter process, also known as Tailored Heat Treated Blank (THTB), the laser heat treatment enables the local tailoring of the material properties [4]. The biggest challenge for the successful production of THTB is the definition of an appropriate heat treatment layout [5]. It is nec
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