Laser-based powder bed fusion of non-weldable low-alloy steels
Artikel i vetenskaplig tidskrift, 2021

This study focuses on the processability of four low-alloy steels (AISI 4130, 4140, 4340 and 8620) via laser-based powder bed fusion (LB-PBF). In the as-built condition, the alloys consisted of tempered martensite that was the result of an intrinsic heat treatment (IHT) during LB-PBF. In terms of defects, a distinct transition in porosity was observed that correlated to the volumetric energy density (VED). At low VED, specimens contained a lack of fusion porosity, while at high VED, they contained keyhole porosity. Additionally, cold cracking was observed in 4140 and 4340 specimens produced at low/intermediate VEDs. This cracking could be mitigated by increasing the VED or laser power, as both enhance the IHT. This enhanced IHT lowered the material hardness below specific thresholds (<500HV 4340 and <460 4140), increasing ductility and allowing the specimens to avoid cracking. From these findings, crack-free, high-density (>99.8%) low-alloy steel specimens were produced without the requirement of build plate preheating.

Laser-based powder bed fusion

low-alloy steels

keyhole porosity

cold cracking

martensite tempering

lack of fusion porosity

intrinsic heat treatment

Författare

William Hearn

Chalmers, Industri- och materialvetenskap, Material och tillverkning

Robert Steinlechner

Chalmers, Industri- och materialvetenskap, Material och tillverkning

Eduard Hryha

Chalmers, Industri- och materialvetenskap, Material och tillverkning

Powder Metallurgy

0032-5899 (ISSN)

Vol. In Press

Ämneskategorier

Bearbetnings-, yt- och fogningsteknik

Annan materialteknik

Metallurgi och metalliska material

DOI

10.1080/00325899.2021.1959695

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Senast uppdaterat

2021-08-20