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Mechanical characterization and fatigue assessment of wire and arc additive manufactured HSLA steel parts
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Additive manufacturing is one of the main foundations of Industry 4.0. It aims,
particularly, to increase productivity, reducing material waste due to machining and bring
many advantages that overcome the conventional manufacturing processes. Wire and Arc
Additive Manufacturing (WAAM) is an additive manufacturing process that employs an
electric arc as heat source in order to melt and add material. It shows great versatility and
freedom to fabricate parts using a layer-by-layer method of deposition. Despite the clear
advantages presented, there still needs more progress in order to make it industrially
feasible. One of the main challenges it faces is studying the mechanical properties bet on
the desired geometry, type of material and the adopted parameters before employing these
components in critical operational loading conditions.
This dissertation aimed to assess the mechanical properties and fatigue resistance of
HSLA parts manufactured by this technology. In this way, two type of samples were
produced – one of low heat-input and another of high heat-input, in which the changing
variable was the travel speed. For each type, three thin walled parts were obtained,
measuring 180 x 100 mm each.
After manufacturing all the required samples, three different regions were analysed –
bottom, middle and top. Next, all parts were assiduously prepared in order to proceed
with material characterization as well as testing, specifically, waviness, microstructure,
electrical conductivity, microhardness, uniaxial tensile tests and lastly fatigue tests, with
subsequent fracture surface observation through Scanning Electron Microscope (SEM).
Fatigue tests were performed at room temperature on low heat-input samples with
constant stress amplitude, stress ratio R=0.1 and frequencies between 12 Hz and 15 Hz.
The S-N curve of the experimental results is presented along with an explanation within
the context of the other characterization techniques results.
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Palavras-chave
Additive Manufacturing WAAM Welding HSLA steel Mechanical properties Fatigue