G2 Master’s thesis, polytechnic Master’s thesis

Weldability of powder bed fusion fabricated stainless steel 316L sheets to cold rolled sheet metal


Open Access publication

LUT Authors / Editors

Publication Details
Authors: Laitinen Ville
Publishing place: LUTPub
Publication year: 2015
Language: English
JUFO-Level of this publication:
Open Access: Open Access publication
Location of the parallel saved publication: http://urn.fi/URN:NBN:fi-fe2015082611017

Abstract

Weldability of powder bed fusion (PBF) fabricated components has come to
discussion in past two years due to resent developments in the PBF
technology and limited size of the machines used in the fabrication
process. This study concentrated on effects of energy input of welding
on mechanical properties and microstructural features of welds between
PBF fabricated stainless steel 316L sheets and cold rolled sheet metal
of same composition by the means of destructive testing and microscopic
analysis. Optical fiber diameter, laser power and welding speed were
varied during the experiments that were executed following one variable
at a time (OVAT) method.

One of the problems of welded PBF fabricated components has been
lower elongations at break comparing to conventionally manufactured
components. Decreasing energy input of the laser keyhole welding
decreased elongations at break of the welded specimens. Ultimate tensile
strengths were not affected significantly by the energy input of the
welding, but fracturing of the specimens welded using high energy input
occurred from the weld metal. Fracturing of the lower energy input welds
occurred from the PBF fabricated base metal. Energy input was found to
be critical factor for mechanical properties of the welds. Multioriented
grain growth and formation of neck at fusion zone boundary on the cold
rolled side of the weld was detected and suspected to be result from
weld pool flows caused by differences in molten weld pool behaviour
between the PBF fabricated and cold rolled sides of the welds.


Last updated on 2019-23-01 at 09:57