Laser Defocusing Effect on the Microstructure and Defects of 17-4PH Parts Additively Manufactured by SLM at a Low Energy Input

In this paper, the microstructure, defects, hardness, and tensile strength of the 17-4PH specimens manufactured additively using the selective laser melting (SLM) technique were studied. The analyzed parts (10 mm size cubic specimens and tensile specimens) were manufactured with different defocus pa...

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Bibliographic Details
Published inMetals (Basel ) Vol. 11; no. 4; p. 588
Main Authors Leo, Paola, Cabibbo, Marcello, Del Prete, Antonio, Giganto, Sara, Martínez-Pellitero, Susana, Barreiro, Joaquin
Format Journal Article
LanguageEnglish
Published Basel MDPI AG 01.04.2021
Subjects
Additive manufacturing
Alloys
characterization
Cooling
Crystal defects
Defocusing
Energy
Grain size
Hardness
Image transmission
Influence
iron alloy
Laser beam melting
laser defocusing
Lasers
Mechanical properties
Microscopes
Microstructure
microstructure evolution
Parameters
Phase ratio
selective laser melting
Stainless steel
Tensile strength
Tensile tests
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Summary:In this paper, the microstructure, defects, hardness, and tensile strength of the 17-4PH specimens manufactured additively using the selective laser melting (SLM) technique were studied. The analyzed parts (10 mm size cubic specimens and tensile specimens) were manufactured with different defocus parameter values (−1, 0, +1 mm) in order to evaluate this effect with a low power laser (38 W). The study was carried out on three different sections of each cubic specimen, one perpendicular to the laser beam or SLM manufacturing direction (transversal section), and another two parallel to the laser beam direction (longitudinal sections). The specimens microstructures were analyzed with an X-ray diffraction technique, as well as optical, scanning electron, and transmission electron microscopes. Image J software was used to characterize the defects and phase ratio. In addition, hardness and tensile tests were performed according to the corresponding standards. The results show that the amount of austenitic phase and the average grain size varied with defocusing. The percentage of defective area was less than 0.25%. The analyzed defocus distance did not affect the number and average size of the defects. Adjusting the defocusing SLM parameter is important for manufacturing parts with good mechanical properties.
ISSN:2075-4701
2075-4701
DOI:10.3390/met11040588