Zhang Hai-ou, Rui Wang, Liye Liang and Wang Gui-lan
The paper aims to introduce the fabrication of a medium steel aircraft part by hybrid deposition and micro-rolling technology (HDMR) and illustrate its advantages, microstructure…
Abstract
Purpose
The paper aims to introduce the fabrication of a medium steel aircraft part by hybrid deposition and micro-rolling technology (HDMR) and illustrate its advantages, microstructure features and mechanical properties of the part.
Design/methodology/approach
The HDMR technology contains two procedures happening almost at the same time: the welding deposition procedure and then the micro-rolling procedure. It takes the gas metal arc welding as the heat source to melt a metal wire and deposit metal in the welding deposition procedure. The metal just deposited is rolled synchronously by a micro roller following the welding torch in micro-rolling procedure almost at the same time layer by layer. The paper presents a contrast of the grain morphology of metal parts produced respectively by HDMR and freedom arc deposition (FAD) and the mechanical properties of metal parts of the same metal from HDMR casting, forging and FAD methods.
Findings
HDMR breaks the dendrite grain of welding beads into the fine crisscross grains. The mechanical properties of metal parts are improved distinctly by the micro-rolling procedure compared to casting, forging and FAD.
Practical implications
In addition, the application of HDMR technology has succeeded in the fabrication of an eligible aircraft metal part, which is quite difficult to achieve using other additive manufacturing (AM) or casting technologies.
Originality/value
HDMR has the advantage of equiponderance manufacturing by micro-rolling compared to other AM technologies. The metal part fabricated by HDMR technology obtains the fine crisscross grains and brings hope for AM metal components with excellent mechanical properties for aircraft applications.
Details
Keywords
Mingkang Zhang, Yongqiang Yang, Changhui Song, Yuchao Bai and Zefeng Xiao
This study aims to focus on the heat treatment influence on the corrosion resistance, adhesion of Streptococcus mutans and mechanical properties of CoCrMo alloys manufactured by…
Abstract
Purpose
This study aims to focus on the heat treatment influence on the corrosion resistance, adhesion of Streptococcus mutans and mechanical properties of CoCrMo alloys manufactured by the selective laser melting (SLM).
Design/methodology/approach
CoCrMo alloys were manufactured using the Dimetal-100 machine. X-ray diffraction (XRD), metallographic analysis, scanning electron microscopy (SEM), electrochemical corrosion, Vickers microhardness and tensile tests were used to characterize SLM-produced CoCrMo alloys and compare them with the ones manufactured by casting and with the ASTM F75 standard.
Findings
The electrochemical results showed that SLM900 samples had the best corrosion resistance in artificial saliva. The adhesion results showed least propagation and overall quantity of Streptococcus mutans on the SLM900 sample. The microhardness, tensile and yield strength of As-SLM, SLM900 and SLM1200D samples were measured according to the ASTM F75 standard. The elongation of SLM900 was less than 8 per cent, which does not meet the standard specifications. Analysis of the fracture morphology showed that the fracture mechanisms of As-SLM and SLM1200D belong to the quasi-cleavage fracture type, and the mechanical fracture mechanism of SLM900 can be characterized as brittle fracture.
Originality/value
This paper presents the adhesion properties of Streptococcus mutans on the surface of CoCrMo alloys manufactured by SLM and proposes how to regulate the effect of the heat treatment on the corrosion resistance and mechanical properties of CoCrMo alloys manufactured by SLM.