Columnar grain width control for SS316L via hatch spacing manipulation in laser powder bed fusion

Abstract

This study provides a quantitative way to tailor the grain structure in laser powder bed fusion (LPBF). Square-bottomed columnar grains (SCGs) were developed with a certain width roughly equal to the hatch spacing. The development of SCGs relied on different distinguishable regions, which were identified based on the differences in microstructural features between the melt-pool side and centreline. High lattice rotation accumulated at the melt-pool centreline, leading to grain boundaries forming at the centreline regions. The ultrasonic attenuation measurements and microhardness tests further validated the controllable properties. The findings indicated a novel approach to customise the material property.

GRAPHICAL ABSTRACT

IMPACT STATEMENT

A method to quantitatively control the columnar grain width in laser powder bed fusion was uncovered. The controllable properties were indicated, and the formation mechanism was revealed.

KEYWORDS:

• Laser powder bed fusion
• hatch spacing
• columnar grain
• crystallographic texture
• stainless steel 316L

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by A*STAR Science and Engineering Research Council [Grant Number A20F9a0045]; Shun Hing Institute of Advanced Engineering, The Chinese University of Hong Kong [Grant Number RNE-p2-21].