Forming quality control of Laser Powder Bed Fusion GH3536 alloy: Surface quality, defects, and microstructure

This study investigates the influence of volume energy density (VED) on surface quality, density, defects, and microstructure of laser powder bed fusion (L-PBF) GH3536 alloy. Specimens fabricated below 80 J/mm3 exhibit lack-of-fusion pores on surfaces and internally, with pore density decreasing but crack initiation occurring as VED increases. Density consistently exceeds 99.5%, peaking at 99.85% (VED = 167 J/mm3). Excessive VED (208 J/mm3) induces surface warping, reduces cracking, but increases pore size/quantity, causing marginal density reduction. Lack-of-fusion defects nucleate microcracks distributed in layer bands; cracks propagate along high-angle grain boundaries following grain growth directions with significant localized stress. Higher VED increases melt pool overlap rate (70.49% at 208 J/mm3) and aspect ratio (width/depth = 6.9), while reducing cooling rates to 1.2 × 105 K/s.