Preliminary Investigation on SLM of ASTM A131 EH36 High Tensile Strength Steel for Shipbuilding Applications

• Main Authors: Wu, Wenjin, Tor, Shu Beng, Chua, Chee Kai, Liu, Zhonghong, Lui, Onn Kit Basil, Aziz Amirali Merchant
• Other Authors: School of Mechanical and Aerospace Engineering
• Format: Conference or Workshop Item
• Language: English
• Published: 2016
• Subjects: 3D printing; Additive manufacturing
• Online Access: https://hdl.handle.net/10356/84206; http://hdl.handle.net/10220/41695
• Institution: Nanyang Technological University

In this preliminary investigation of selective laser melting (SLM) of EH36 high tensile strength steel, a 175 W Yb:YAG laser in continuous wave mode was used to produce EH36 test specimens. The laser beam profile follows the Gaussian distribution and has a wavelength of 1.064 nm, with a focaldiameter of 81 µm. The powder layer thickness was set at 50 µm. The stainless steel substrate plate was preheated to 100 °C. The scanning speeds were varied from 260 mm/s to 880 mm/s, and hatch spacing were varied from 0.08 mm to 0.12 mm, to obtain the various energy densities. The highest density value of 7.64 g/cm3 was obtained at an energy density of 92 J/mm3 using parameters of 0.12 mm hatch spacing, powder at 175W, 50 mm layer thickness and 320 mm/s laser scanning speed. Compared to the relative density of the compacted supplied powder (7.83 g/cm3), the results translated to 97.57% fully dense part. Micrographs were obtained using light optical microscopy, which showed slight porosities in the SLM built part. X-ray diffraction and scanning electron microscropy revealed BCC phases and martensitic microstructure respectively.