A. Rangesh and William O'Neill
The purpose of this paper is to investigate the feasibility of using a pulsed Tungsten inert gas arc to fully melt and consolidate stainless steel powder onto a stainless steel…
Abstract
Purpose
The purpose of this paper is to investigate the feasibility of using a pulsed Tungsten inert gas arc to fully melt and consolidate stainless steel powder onto a stainless steel substrate. The technology aims to bridge the gap between selective laser sintering or laser melting and wire fed weld deposition by providing good quality and better resolution at a lower cost.
Design/methodology/approach
Current settings between 5 and 30 A and frequencies between 0 and 200 Hz were used to consolidate stainless steel powder onto a substrate. Results were catalogued based on surface roughness using white light interferometery to develop a process map.
Findings
Velocity independent thresholds of current (17 A minimum) and frequency (20 Hz minimum) were found, with better quality achieved at higher pulse frequencies. The microstructure of the samples were examined showing grain sizes of ≈3 μm for equiaxed grains and up to 20 μm for the columnar grains. Vickers hardness measurements showed only a 20 point average hardness increase in the HAZ compared to the substrate.
Research limitations/implications
The study showed that although it was possible to deposit stainless steel tracks, it was not possible to reduce the track resolution to less than 400 μm at any of the process settings.
Originality/value
The research aims to investigate the use of a readily available, low cost, heat source to consolidate metal powder. The suitability of such a heat source for rapid prototyping is investigated using a variety of objective tests to provide a balanced view of its capabilities and limitations.
Details
Keywords
Jianfeng Sun, Zhou Yang, Yongqiang Yang and Di Wang
This paper aims to analyze the different between matrix and overhanging structure and indicate the laws and mechanism of overhanging structure formed by selective laser melting…
Abstract
Purpose
This paper aims to analyze the different between matrix and overhanging structure and indicate the laws and mechanism of overhanging structure formed by selective laser melting (SLM).
Design/methodology/approach
This paper includes processing the matrix and overhanging structure with optimized parameters and analyzing the microstructure and properties of matrix and overhanging with OM, SEM, XRD etc. so as to analyze and reveal the laws and mechanism of overhanging structure formed by SLM.
Findings
The solidification of overhanging structure begins from the structure’s edge and extends to its center; the distribution of the Cr with a diameter of 250 nm in the Fe matrix is uniform; the grain in the overhanging structure is growing faster than the grain in the matrix. The overhanging structure mainly composed by austenite has no apparent layer. Moreover, the microhardness of the overhanging structure is 258.6-294.0 Hv0.3, smaller than the microhardness of the matrix which is 236.4-300.9 Hv0.3.
Originality/value
This paper clarifies how to manufacture overhanging structure and non-overhanging structure matrix with optimized parameters, analyzes the microstructures and compares the properties of both overhanging structure and non-overhanging structure “matrix”, so as to analyze the reasons for the forming of the overhanging structure, which in turn lauds basic data foundation for the theoretical studies in the future.