Microstructure and loading direction dependent hardening and damage behavior of laser powder bed fusion AlSi10Mg

Abstract

The correlation between mechanical behavior and heterogeneous microstructure is still unclear for laser powder bed fusion AlSi10Mg. The present work investigates strain hardening and damage mechanisms with different build platform temperatures (35 °C and 200 °C) and loading directions (horizontal and vertical, building direction being vertical) to probe the effects of microstructure size and melt pool border orientation. The 35 °C microstructure involves load direction independent properties, with ductility determined by damage initiation occurring extremely close to final failure. In contrast, the 200 °C microstructure exhibits anisotropic mechanical behavior, as revealed by higher strain hardening capacity, earlier damage initiation and more dispersed damage distribution for the vertical loading direction. Although the vertical samples generally involve strain localization and crack propagation along the melt pool border, their ductility is not compromised compared to the horizontal counterparts. We attempt to explain these hardening and damage behaviors with stress partition and trade-off between phase stress and strain gradient.