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Lattice structure tensile specimen manufactured with laser melting (LM) process out of the material H13. Show image information
Partner of the DMRC Show image information
Partner of the DMRC Show image information
Quality control during a Laser Sinter (LS) build job by a researcher of the DMRC Show image information
Fused Deposition Modeling (FDM) process during the manufacture of an Ultem 9085 part Show image information
Additive manufactured reaction wheel bracket for telecomunication satellites Show image information
Employees of the DMRC working with the "freeformer" from Arburg Show image information
Tactile measurement of a SLM part with a Coordinatemeasuring machine (CMM) Show image information
Powder particles are used as raw material for laser-based additive manufacturing Show image information

Lattice structure tensile specimen manufactured with laser melting (LM) process out of the material H13.

Partner of the DMRC

Partner of the DMRC

Quality control during a Laser Sinter (LS) build job by a researcher of the DMRC

Fused Deposition Modeling (FDM) process during the manufacture of an Ultem 9085 part

Additive manufactured reaction wheel bracket for telecomunication satellites

Employees of the DMRC working with the "freeformer" from Arburg

Tactile measurement of a SLM part with a Coordinatemeasuring machine (CMM)

Powder particles are used as raw material for laser-based additive manufacturing

Optimization of Material Properties of selective Laser-Melted Aluminum Alloy 7075

FIGURE 1 Optical micrographs of the specimen after SLM processing EN AW-7075 manufactured with a 473.15 K pre-heated building platform

Objectives

Objectives Experience from conventional manufacturing shows a good performance of the high-strength aluminum alloy EN AW 7075 which leads to frequent use in automotive and aerospace sector. Scientific investigations on the processability of this alloy in the SLM process shows that prepared samples have anisotropic behavior due to process-induced hot cracks (Figure 1). Furthermore, it was not possible to determine solid results regarding the fracture mechanical characterization. Due to its chemical composition, aluminum alloy EN AW 7075 has a high solidification interval. As a result, the melting and solidification of the material results in a high affinity for the formation of hot cracks. For industrial use, these hot cracks must be avoided.

Optical micrographs of the specimen after SLM processing mixed aluminum alloy manufactured with a 673.15 K pre-heated building platform

Procedure

An investigation documented in literature shows that addition of 4 Wt.-% Silicon avoids hot cracking. This is due to a reduction of the thermal expansion coefficient. Furthermore another investigation shows that an increase of the pre-heating temperature of the building platform reduces the number of hot cracks in selective laser melted EN AW 7075. In practice, pure silicon is not always available for the modification of the powder, which is why a practice-oriented approach to the production of a mixed alloy made of high-strength EN AW-7075 and silica-rich AlSi10Mg is pursued in this context.

Achievements

The production of a mixed aluminum alloy based on the high-strength alloy EN AW-7075 led to process-reliable processing using SLM. When using an adequate process parameter set, the samples produced have an almost pore- free appearance without detectable hot cracks (Figure 2). A subsequent heat treatment leads to an increase in the mechanical and fracture mechanical characteristics of the mixed aluminum alloy. The approach of mixing two available powders makes it possible to compensate for negative mechanical and fracture mechanical properties and to generate additively processable material.

Contact

Prof. Dr.-Ing. Gunter Kullmer

Angewandte Mechanik

Gunter Kullmer
Phone:
+49 5251 60-5320
Fax:
+49 5251 60-5322
Office:
IW1.878
Web:

Office hours:
montags 11.00 - 12.00 Uhr

Dr.-Ing. Jan-Peter Brüggemann

Angewandte Mechanik

Materialforschung

Jan-Peter Brüggemann
Phone:
+49 5251 60-4388
Fax:
+49 5251 60-5322
Office:
Y 0 217
Web:

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