Strategy of Residual Stress Determination on Selective Laser Melted Al Alloy Using XRD

Abstract

Selective laser melting (SLM) is known to generate large and anisotropic residual stresses in the samples. Accurate measurement of residual stresses on SLM-produced samples is essential for understanding the residual stress build-up mechanism during SLM, while a dramatic fluctuation can be observed in the residual stress values reported in the literature. On the basis of studying the influence of surface roughness on residual stress measured using X-ray diffraction (XRD), we propose a procedure coupling XRD technique with pretreatment consisting of mechanical polishing and chemical etching. The results highlight that residual stresses measured using XRD on as-built SLM-produced samples with high surface roughness are significantly lower than those measured on samples with finished surface, which is due to the stress relaxation on the spiked surface of as-built samples. Surface distribution of residual stresses and the effect of scanning strategy were systematically investigated for SLM-produced AlSi10Mg samples. Microstructural morphology was observed at the interface between sample and building platform and was linked to the surface distribution of residual stresses. This procedure can help us accurately measure the residual stresses in SLM-produced samples and thus better understand its build-up mechanism during the SLM process.

Influence of Postprocessing on Wear Resistance of Aerospace Steel Parts Produced by Laser Powder Bed Fusion

“…Another problem is the postprocessing of the obtained surfaces with a complex character and internal cavities that are mostly required for the parts produced by additive manufacturing [13][14][15]. Most of the postprocessing methods are oriented on the treatment of linear surfaces as mechanical abrasive [16][17][18] (the achievable roughness arithmetic mean deviation R a is of 0.04 µm [19]), laser-plasma [14,[20][21][22][23], ion-plasma (achievable average microroughness is up to 0.1-0.2 µm with a decrease in pulse width to 1.5 ns [24][25][26]), or electron beam [27][28][29] polishing that showed its effectiveness only on small flat areas with achievable microroughness more than 1 µm, ultrasonic plastic deformation, or their combination. Furthermore, the methods based on mechanical machining often leave cutting traces or traces of erosion such as those from cavitation-abrasive finishing that can dramatically influence the functional surfaces' wear resistance.…”

Farklı bağıl yoğunluklardaki Inconel 718 ve Ti6Al4V biyomedikal parçaların seçici lazer ergitme (SLE) metoduyla üretiminin simülasyonu

“…Toz yataklı eklemeli imalat yöntemlerinde oluşan maksimum sıcaklıkların ve sıcaklık değişimlerinin oluşan kalıntı gerilmeleri ve şekil değişimlerini doğrudan etkilediği bilinmektedir [64][65][66]. Şekil 2'de üretilen tüm parçaların imalat yüksekliğine karşılık gelen maksimum sıcaklıkları verilmiştir.…”

“…Var olan gerinim ε vo , lazer taraması sırasında meydana gelen hızlı ısınma ve soğuma neticesinde; plastik deformasyondan meydana gelen εplastik , termal genişleme ve daralmadan meydana gelen ε termal ve faz değişimlerinden kaynaklanan ε faz gerinimlerinin toplamına eşittir (Eş. 1)[62][63][64]. Lazer taraması sırasında oluşan toplam gerinim değerini εtoplam ile ifade edecek olursak, toplam gerinim değeri, elastik gerinim değeri ε elastik ve var olan gerinim değeri ε vo 'nun toplamına eşit olacaktır (Eş.…”

Simultaneously minimizing residual stress and enhancing strength of selective laser melted nano-TiB2 decorated Al alloy via post-uphill quenching and ageing

“…The residual stresses consisting of two components, along the building direction (BD) or scanning direction (SD) and normal to the BD or SD, were evaluated using the PROTO-iXRD X-ray stress analyser with Cr-K α radiation. To accurately measure the residual stress in the SLMed samples, the samples were pre-treated by mechanical polishing and chemical etching, as proposed in [34]. Al (311) diffraction peaks were chosen for residual stress measurement using the sin 2 ψ method (Fig.…”