scholarly journals Cracking Behavior of René 104 Nickel-Based Superalloy Prepared by Selective Laser Melting Using Different Scanning Strategies

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2149
Author(s):  
Kai Peng ◽  
Ranxi Duan ◽  
Zuming Liu ◽  
Xueqian Lv ◽  
Quan Li ◽  
...  
Keyword(s):  
Residual Stress ◽  
Relative Density ◽  
Selective Laser Melting ◽  
Laser Melting ◽  
High Quality ◽  
Cracking Behavior ◽  
Nickel Based Superalloy ◽  
Size Number ◽  
Cracking Performance ◽  
Scanning Strategies

Eliminating cracks is a big challenge for the selective laser melting (SLM) process of low-weldable Nickel-based superalloy. In this work, three scanning strategies of the snake, stripe partition, and chessboard partition were utilized to prepare René 104 Ni-based superalloy, of which the cracking behavior and the residual stress were investigated. The results showed that the scanning strategies had significant effects on the cracking, residual stress, and relative density of the SLMed René 104 superalloy. The scanning strategies with more partitions boosted the emergence of cracks, as high-density cracks occurred in these samples. The overlapping zone (OZ) of the scanning partition was also susceptible to cracking, which increased the size, number, and density of the cracks. The cracking performance was relatively moderate in the snake-scanned samples, while that in the chessboard-partition-scanned samples was the most severe. It is concluded that the partition scanning strategies induced more cracks in the SLMed René 104 superalloy, of which the residual stress was apparently reduced. Therefore, it is necessary to design scanning strategies with optimized scanning partitions and overlaps to avoid cracking and acquire a high-quality, near fully dense, low-weldable Nickel-based superalloy using SLM.

scholarly journals Effect of Process Parameters and High-Temperature Preheating on Residual Stress and Relative Density of Ti6Al4V Processed by Selective Laser Melting

Materials ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 930 ◽  
Author(s):  
Martin Malý ◽  
Christian Höller ◽  
Mateusz Skalon ◽  
Benjamin Meier ◽  
Daniel Koutný ◽  
...  
Keyword(s):  
Residual Stress ◽  
High Temperature ◽  
Residual Stresses ◽  
Relative Density ◽  
Selective Laser Melting ◽  
Process Parameters ◽  
Stress Reduction ◽  
Laser Melting ◽  
Preheating Temperature ◽  
Laser Velocity

The aim of this study is to observe the effect of process parameters on residual stresses and relative density of Ti6Al4V samples produced by Selective Laser Melting. The investigated parameters were hatch laser power, hatch laser velocity, border laser velocity, high-temperature preheating and time delay. Residual stresses were evaluated by the bridge curvature method and relative density by the optical method. The effect of the observed process parameters was estimated by the design of experiment and surface response methods. It was found that for an effective residual stress reduction, the high preheating temperature was the most significant parameter. High preheating temperature also increased the relative density but caused changes in the chemical composition of Ti6Al4V unmelted powder. Chemical analysis proved that after one build job with high preheating temperature, oxygen and hydrogen content exceeded the ASTM B348 limits for Grade 5 titanium.

scholarly journals The Effect of a Scanning Strategy on the Residual Stress of 316L Steel Parts Fabricated by Selective Laser Melting (SLM)

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1821 ◽  
Author(s):  
Di Wang ◽  
Shibiao Wu ◽  
Yongqiang Yang ◽  
Wenhao Dou ◽  
Shishi Deng ◽  
...  
Keyword(s):  
Residual Stress ◽  
Selective Laser Melting ◽  
Laser Scanning ◽  
Effective Means ◽  
Laser Melting ◽  
Scanning Strategy ◽  
Deformation Degree ◽  
316L Steel ◽  
Stress And Deformation ◽  
Scanning Strategies

The laser scanning strategy has an important influence on the surface quality, residual stress, and deformation of the molten metal (deformation behavior). A divisional scanning strategy is an effective means used to reduce the internal stress of the selective laser melting (SLM) metal part. In order to understand and optimize the divisional scanning strategy, three divisional scanning strategies and an S-shaped orthogonal scanning strategy are used to produce 316L steel parts in this study. The influence of scanning strategy on the produced parts is verified from the aspects of densification, residual stress distribution and deformation. Experiments show that the 316L steel alloy parts adopted spiral divisional scanning strategy can not only obtain the densification of 99.37%, but they also effectively improve the distribution of residual stress and control the deformation degree of the produced parts. Among them, the spiral divisional scanning sample has the smallest residual stress in plane direction, and its σx and σy stress are controlled within 204 MPa and 103 MPa. The above results show that the spiral divisional scanning is the most conducive strategy to obtain higher residual stress performance of SLM 316L steel parts.

Determination of residual stress for Inconel 718 samples fabricated through different scanning strategies in selective laser melting

2020 ◽  
Author(s):  
Vignesh Ram Kumar Rajendran ◽  
Kiriti Mamidi ◽  
Bharath Ravichander ◽  
Behzad Farhang ◽  
Amirhesam Amerinatanzi ◽  
...  
Keyword(s):  
Residual Stress ◽  
Selective Laser Melting ◽  
Inconel 718 ◽  
Laser Melting ◽  
Scanning Strategies

The effect of hatch angle rotation on parts manufactured using selective laser melting

2019 ◽  
Vol 25 (2) ◽  
pp. 289-298 ◽  
Author(s):  
Joseph Henry Robinson ◽  
Ian Robert Thomas Ashton ◽  
Eric Jones ◽  
Peter Fox ◽  
Chris Sutcliffe
Keyword(s):  
Residual Stress ◽  
Surface Roughness ◽  
Selective Laser Melting ◽  
Pure Titanium ◽  
Commercially Pure Titanium ◽  
Laser Melting ◽  
Content Type ◽  
Axial Tensile ◽  
Effects Of Rotation ◽  
Scanning Strategies

Purpose This paper aims to present an investigation into the variation of scan vector hatch rotation strategies in selective laser melting (SLM), focussing on how it effects density, surface roughness, tensile strength and residual stress. Design/methodology/approach First the optimum angle of hatch vector rotation is proposed by analysing the effect of different increment angles on distribution of scan vectors. Sectioning methods are then used to determine the effect that the chosen strategies have on the density of the parts. The top surface roughness was analysed using optical metrology, and the tensile properties were determined using uni-axial tensile testing. Finally, a novel multi-support deflection geometry was used to quantify the effects of rotation angles on residual stress. Findings The results of this research showed that the hatch rotation angle had little effect on the density, top surface roughness and strength of the parts. The greatest residual stress deflection was measured parallel to unidirectional scan vectors. The use of hatch rotations other than alternating 90° showed little benefit in lowering the magnitude of residual stresses. However, the use of rotation angles with a good suitability measure distributes stresses in all directions more evenly for certain part geometries. Research limitations/implications All samples produced in this work were made from commercially pure titanium, therefore care must be taken when applying these results to other materials. Originality/value This paper serves to increase the understanding of SLM scanning strategies and their effect on the properties of the material.

scholarly journals Selective Laser Melting of Maraging Steel Using Synchronized Three-Spot Scanning Strategies

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1905
Author(s):  
Chung-Wei Cheng ◽  
Wei-You Jhang Jian ◽  
Bhargav Prasad Reddy Makala
Keyword(s):  
Relative Density ◽  
Maraging Steel ◽  
Selective Laser Melting ◽  
Surface Hardness ◽  
Industrial Applications ◽  
Laser Melting ◽  
Manufacturing Method ◽  
Part Quality ◽  
Spot Scanning ◽  
Scanning Strategies

The selective laser melting (SLM) process, a kind of metal additive manufacturing method, can produce parts with complex geometries that cannot be easily manufactured using material removal processes. With increasing industrial applications, there are still issues such as part quality and productivity that need to be resolved. In this study, maraging steel parts fabricated by synchronized three-spot scanning strategies, i.e., lateral spatial (LS) and spatial inline (SiL), are firstly presented. The LS and SiL represent the three-spot offset direction is perpendicular and parallel to the scanning direction, respectively. A laboratory SLM machine equipped with a fiber laser and three-spot module is used to fabricate the maraging steel parts with two scanning strategies, i.e., LS and SiL. The influence of these scanning strategies on the surface roughness, relative density, hardness, molten pool shapes, and microstructures are investigated. The relative density (~99.02%) and surface hardness (~34.0 HRC) are experimentally found to be higher than the SiL by the LS scanning strategy.

Effect of rescanning with reduced interlayer times on microstructure and properties of titanium alloy via selective laser melting

2021 ◽  
pp. 095440542110412
Author(s):  
Yiqing Ma ◽  
Meiping Wu ◽  
Weipeng Duan ◽  
Xiaojin Miao ◽  
Haohao Li ◽  
...  
Keyword(s):  
Residual Stress ◽  
Relative Density ◽  
Selective Laser Melting ◽  
Time Cost ◽  
Laser Melting ◽  
Scanning Strategy ◽  
Element Analysis ◽  
Α Phase ◽  
Stress Optimization ◽  
Manufacturing Time

In the process of selective laser melting, laser rescanning technology is often used to optimize the residual stress and other properties of the formed parts. In order to improve the performance of parts and reduce the manufacturing time concurrently, this paper proposed a combined rescanning strategy. Based on finite element analysis, molten pool solidification behavior was simulated and studied. Ti6Al4V alloy samples were fabricated and analyzed by changing the rescanning strategies and process parameters. The microstructure, relative density, size of pore defects and residual stress were investigated under different rescanning strategies. It can be seen that the average cooling rate ranked in a descending order of SLM > re-SLM+IL1 > re-SLM, and samples formed by rescanning without layer interval had the best relative density and residual stress optimization effect, while the microstructure of each scanning strategy was all acicular α′ phase. When the number of rescanning interlayers and laser power was “one-layer” and 140 W respectively, the residual stress went down from 353 to 294 MPa. Finally, a simplified model was proposed to calculate the time cost for fabrication of rescanning with reduced interlayer times.

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