che_march-2024 - 37

Process
Simulation
Proactively Identify &
Mitigate Process
Engineering Issues
Process simulation is a comprehensive and
risk-free technique to design, optimize, and
troubleshoot a variety of industrial processes.
FIGURE 5. Tensile curves of the three test conditions (A, B and C) show a correlation
between scan speed and ductility
The energy input to the material can be related to the main
process parameters, such as laser power, scan speed,
hatch spacing and layer thickness. At a low scan speed and
a high laser power, the energy input is high, so more powders
are melted at an elevated temperature, thus creating
porosity defects.
Deformation twinning (Figure 4) and induced plasticity
were revealed from metallography samples after tensile
testing. It is believed that deformation twinning is
responsible for the elevated plasticity, a positive effect,
of the tested samples, regardless of the level of porosity
found [12-15]. Deformation twinning, on the other
hand, can have an adverse effect on ductility in other
alloy systems [16].
As laser speed increases, the depth of penetration
is reduced, along with the interlayer bonding between
the layers, thereby increasing porosity [12]. Porosity reduction
benefits the material fatigue life, as well as mechanical
properties [17, 18]. The subsequent tensile
testing results (Figure 5) show that the build with the
fastest print speed had the largest ductility (around 90%)
before failure.
Findings
The influence of varying SLM parameters - namely hatch
distance, scan speed and power - on the internal structure
and porosity of the samples was investigated. Defects
encountered included spherical porosities, irregularly
incomplete fusion holes and cracks (indicating a lack of
fusion). Spherical porosities were randomly distributed,
while the lack of fusion was found to be between layers.
All these issues are clearly affected by layer thickness,
hatch spacing, scan speed and laser power. Deformation
twinning was found to enhance plasticity, despite the
presence of pores.
It was shown that processing at the selected high
scanning speed is the most appropriate for minimizing
porosity at the optimum hatch distance of 0.05
mm. Mechanical properties of the samples fabricated
using varying strategies did not show significant differences
in the yield strength and ultimate tensile
strength values. These results will be used to complement
upcoming work, which will facilitate improved quality and
delivery time of AM parts, while maintaining strength, ductility
and hardness.
For CPI companies, these benefits will result in improved
performance of valves and related components,
CHEMICAL ENGINEERING WWW.CHEMENGONLINE.COM
At E²G | The Equity Engineering Group, Inc.,
we combine our industry experience with
process simulation skills to provide actionable
recommendations that deliver safer and more
reliable systems. Our Process Technology
team helps optimize your pressure relief
and disposal systems, pipe gathering and
distribution networks, compression and pumping
systems, distillation columns and reaction loops,
among others, against unexpected scenarios.
We develop steady and transient flow assurance,
overpressure, optimization, thermal radiation,
and gas dispersion studies, and more with the
required fidelity.
CONTACT E²G TODAY
and start achieving risk management targets,
compliance requirements, and business
objectives.
PREDICT & OPTIMIZE
PROCESS CONTROL
STRATEGIES
MINIMIZE
OPERATIONAL
RISK
MAKE
INFORMED
DECISIONS
REDUCE
OPERATIONAL
COSTS
TECHNOLOGY FORWARD
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