Laser additive manufacturing of Co-Cr alloy and the induced defects thereof


Mahmood M. A., Rehman A. U., Lungu M., Pitir F., SALAMCİ M. U., Ristoscu C., ...Daha Fazla

INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY, cilt.121, sa.1-2, ss.1385-1400, 2022 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 121 Sayı: 1-2
  • Basım Tarihi: 2022
  • Doi Numarası: 10.1007/s00170-022-09395-7
  • Dergi Adı: INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, IBZ Online, Compendex, INSPEC, DIALNET
  • Sayfa Sayıları: ss.1385-1400
  • Anahtar Kelimeler: Laser powder bed fusion, Co-Cr alloys, Lack of fusion and melt flow porosities, X-ray computed tomography, Modelling, POWDER-BED FUSION, MECHANICAL-PROPERTIES, POROSITY, MICROSTRUCTURE, COMPONENTS
  • Gazi Üniversitesi Adresli: Evet

Özet

In laser additive manufacturing (LAM), porosity is a common defect due to the high-temperature gradients involved in the material's recurrent quick liquefaction and solidification. In this study, multi-physics involved in the porosity formation has been explained. For this purpose, a multi-physics-based model is presented to estimate the lack of fusion (LOF)- and melt flow (MFP)-based porosity in the laser powder bed fusion (LPBF) process. The present model relies on the operating conditions and material thermo-physical properties. Melt pool dimensions were computed using a transient thermal model. LOF- and MFP-based porosities were calculated using the melt pool dimensions attained via the thermal distribution model. A total of 15 Cobalt-Chromium (Co-Cr) samples with 10 x 10 x 10 (mm(3)) dimensions were prepared via the LPBF process. All samples were subjected to X-ray computed tomography (XCT) to analyse pore formation and distribution. A close association was identified between modelling and experimental results with a mean absolute deviation of 7-15%. It was found that all Co-Cr samples yielded a combination of micro- and macro-pores. Experimentally, a linear link was determined between laser power and porosity (%) and hatch distance and porosity (%), while the laser scanning speed did not significantly influence the porosity (%). Initially, the porosity (%) remained unchanged with increased volume, energy, and density parameters, and afterward, it decayed linearly. The majority of pores had a volume of 0.010-0.069 mm(3) with a sphericity of 0.30-0.75, which confirms they are a mixture of regular, irregular and elongated shapes. This study provides an effective technique for efficiently estimating the LOF- and MFP-based porosities using input parameters.