scholarly journals Influence of Minor Alloying Element Additions on the Crack Susceptibility of a Nickel Based Superalloy Manufactured by LPBF

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5702
Author(s):  
Mireia Vilanova ◽  
Mari Carmen Taboada ◽  
Ana Martinez-Amesti ◽  
Andrea Niklas ◽  
Maria San Sebastian ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
Research Work ◽  
Crack Density ◽  
Alloying Elements ◽  
Alloying Element ◽  
Factors Affecting ◽  
Powder Bed ◽  
Nickel Based Superalloy ◽  
Grain Structures ◽  
Crack Susceptibility

Inconel 738LC (IN738LC) is a nickel-based superalloy specially used in the hot section components of turbine engines. One of its main drawbacks relies on the cracking susceptibility when it is manufactured by laser powder bed fusion (LPBF). This paper analyzes the influence of minor alloying element concentration on cracking tendency of IN738LC superalloy manufactured by LPBF. For that objective, samples were manufactured using two powders, which presented different minor alloying elements concentration (Si, Zr and B). It was shown that the samples crack tendency was very different depending on the powder used for their manufacturing. In fact, the measured crack density value was 2.73 mm/mm2 for the samples manufactured with the powder with higher minor alloying elements concentration, while 0.25 mm/mm2 for the others. Additionally, a special emphasis has been put on elemental composition characterization in cracked grain boundaries in order to quantify possible Si or Zr enrichment. It has been also studied the differences of solidification ranges and grain structures between both samples as a consequence of different minor alloying elements concentration in order to analyze their effect on crack susceptibility. In this sense, Scheil-Gulliver simulation results have shown that samples with higher Si and Zr contents presented higher solidification range temperature. This fact, as well as an increase of the presence of high angle grain boundaries (HAGB), leaded to an increment in the crack formation during solidification. Therefore, in this research work, an understanding of the factors affecting crack phenomenon in the LPBF manufactured IN738LC was accomplished.

scholarly journals Influence of Laser Powder Bed Fusion Process Parameters on Voids, Cracks, and Microhardness of Nickel-Based Superalloy Alloy 247LC

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3770
Author(s):  
Olutayo Adegoke ◽  
Joel Andersson ◽  
Håkan Brodin ◽  
Robert Pederson
Keyword(s):  
Energy Density ◽  
Process Parameters ◽  
Laser Power ◽  
Crack Density ◽  
Void Formation ◽  
Void Content ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Nickel Based Superalloy ◽  
Density Threshold

The manufacturing of parts from nickel-based superalloy Alloy 247LC by laser powder bed fusion (L-PBF) is challenging, primarily owing to the alloy’s susceptibility to cracks. Apart from the cracks, voids created during the L-PBF process should also be minimized to produce dense parts. In this study, samples of Alloy 247LC were manufactured by L-PBF, several of which could be produced with voids and crack density close to zero. A statistical design of experiments was used to evaluate the influence of the process parameters, namely laser power, scanning speed, and hatch distance (inherent to the volumetric energy density) on void formation, crack density, and microhardness of the samples. The window of process parameters, in which minimum voids and/or cracks were present, was predicted. It was shown that the void content increased steeply at a volumetric energy density threshold below 81 J/mm3. The crack density, on the other hand, increased steeply at a volumetric energy density threshold above 163 J/mm3. The microhardness displayed a relatively low value in three samples which displayed the lowest volumetric energy density and highest void content. It was also observed that two samples, which displayed the highest volumetric energy density and crack density, demonstrated a relatively high microhardness; which could be a vital evidence in future investigations to determine the fundamental mechanism of cracking. The laser power was concluded to be the strongest and statistically most significant process parameter that influenced void formation and microhardness. The interaction of laser power and hatch distance was the strongest and most significant factor that influenced the crack density.

Effects of Alloying Elements on Iron Grain Boundary Cohesion

1997 ◽  
Vol 492 ◽  
Author(s):  
X. Chen ◽  
D. E. Ellis ◽  
G. B. Olson
Keyword(s):  
Molecular Dynamics ◽  
Free Surface ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
First Principles ◽  
Electronic Structure Calculations ◽  
Alloying Elements ◽  
Alloying Element ◽  
Long Time ◽  
Structure Calculations

For a long time, understanding the mechanisms of impurity-promoted embrittlement in iron and the consequent cohesion(decohesion) effects has been a challenge for materials scientists. The role alloying elements play in impurity-promoted embrittlement is important due to either their direct intergranular cohesion(decohesion) effects or effects upon embrittling potency of other impurities. Some alloying elements like Pd and Mo are known to be helpful for intergranular cohesion in iron and some other alloying elements like Mn are known to segregate to and weaken iron grain boundaries dramatically[1]. There have been intensive investigations on these mechanisms for a long time and especially, with the progress in computing techniques in recent years, calculations on more realistic models have become possible[2–4]. In this paper we briefly present our studies on some selected alloying-element/iron grain boundaries(GB) and free surface(FS) systems. The effects of Pd, Mo, Mn and Cr on the Fe Σ5 (031) grain boundary and its corresponding (031) free surface are examined, using a combination of molecular dynamics(MD) and first-principles electronic structure calculations. Section 2 gives a brief introduction to the methods used and Section 3 gives the main results.

scholarly journals Microstructures and Macrosegregation of Al–Zn–Mg–Cu Alloy Billet Prepared by Uniform Direct Chill Casting

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 708
Author(s):  
Li Zhou ◽  
Yajun Luo ◽  
Zhenlin Zhang ◽  
Min He ◽  
Yinao Xu ◽  
...  
Keyword(s):  
Mold Wall ◽  
Direct Chill ◽  
Element Distribution ◽  
Direct Chill Casting ◽  
Electromagnetic Stirring ◽  
Alloying Elements ◽  
Alloying Element ◽  
Casting Method ◽  
Chill Casting ◽  
Cu Alloy

In this study, large-sized Al–Zn–Mg–Cu alloy billets were prepared by direct chill casting imposed with annular electromagnetic stirring and intercooling; a process named uniform direct chill casting. The effects of uniform direct chill casting on grain size and the alloying element distribution of the billets were investigated and compared with those of the normal direct chill casting method. The results show that the microstructures were refined and the homogeneity of the alloying elements distribution was greatly improved by imposing the annular electromagnetic stirring and intercooling. In uniform direct chill casting, explosive nucleation can be triggered, originating from the mold wall and dendrite fragments for grain refinement. The effects of electromagnetic stirring on macrosegregation are discussed with consideration of the centrifugal force that drives the movement of melt from the central part towards the upper-periphery part, which could suppress the macrosegregation of alloying elements. The refined grain can reduce the permeability of the melt in the mushy zone that can restrain macrosegregation.

scholarly journals Optimizing Laser Powder Bed Fusion Parameters for IN-738LC by Response Surface Method

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4879
Author(s):  
Mireia Vilanova ◽  
Rubén Escribano-García ◽  
Teresa Guraya ◽  
Maria San Sebastian
Keyword(s):  
Response Surface ◽  
Response Surface Method ◽  
Process Parameters ◽  
Crack Density ◽  
Processing Parameters ◽  
Optimum Process ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Surface Method

A method to find the optimum process parameters for manufacturing nickel-based superalloy Inconel 738LC by laser powder bed fusion (LPBF) technology is presented. This material is known to form cracks during its processing by LPBF technology; thus, process parameters have to be optimized to get a high quality product. In this work, the objective of the optimization was to obtain samples with fewer pores and cracks. A design of experiments (DoE) technique was implemented to define the reduced set of samples. Each sample was manufactured by LPBF with a specific combination of laser power, laser scan speed, hatch distance and scan strategy parameters. Using the porosity and crack density results obtained from the DoE samples, quadratic models were fitted, which allowed identifying the optimal working point by applying the response surface method (RSM). Finally, five samples with the predicted optimal processing parameters were fabricated. The examination of these samples showed that it was possible to manufacture IN738LC samples free of cracks and with a porosity percentage below 0.1%. Therefore, it was demonstrated that RSM is suitable for obtaining optimum process parameters for IN738LC alloy manufacturing by LPBF technology.

scholarly journals A Review of Factors Affecting the Mechanical Properties of Maraging Steel 300 Fabricated via Laser Powder Bed Fusion

Metals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1273 ◽  
Author(s):  
Barry Mooney ◽  
Kyriakos Kourousis
Keyword(s):  
Mechanical Properties ◽  
Maraging Steel ◽  
Processing Parameters ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Factors Affecting ◽  
Powder Bed ◽  
Porosity Defects ◽  
Research Findings ◽  
Microstructure Density

Maraging steel is an engineering alloy which has been widely employed in metal additive manufacturing. This paper examines manufacturing and post-processing factors affecting the properties of maraging steel fabricated via laser powder bed fusion (L-PBF). It covers the review of published research findings on how powder quality feedstock, processing parameters, laser scan strategy, build orientation and heat treatment can influence the microstructure, density and porosity, defects and residual stresses developed on L-PBF maraging steel, with a focus on the maraging steel 300 alloy. This review offers an evaluation of the resulting mechanical properties of the as-built and heat-treated maraging steel 300, with a focus on anisotropic characteristics. Possible directions for further research are also identified.

Self-propagating high-temperature synthesis microalloying of MoSi2 with Nb and V

2003 ◽  
Vol 18 (8) ◽  
pp. 1842-1848 ◽  
Author(s):  
F. Maglia ◽  
C. Milanese ◽  
U. Anselmi-Tamburini ◽  
Z. A. Munir
Keyword(s):  
Solid Solution ◽  
High Temperature ◽  
Tetragonal Phase ◽  
Synthesis Method ◽  
The Self ◽  
Alloying Elements ◽  
Alloying Element ◽  
Temperature Synthesis ◽  
Starting Mixture ◽  
High Temperature Synthesis

Microalloying of MoSi2 to form Mo(1−x)MexSi2 (Me = Nb or V) was investigated by the self-propagating high-temperature synthesis method. With alloying element contents up to 5 at.%, a homogeneous C11b solid solution was obtained. For higher contents of alloying elements, the product contained both the C11b and the hexagonal C40 phases. The relative amount of the C40 phase increases with an increase in the content of alloying metals in the starting mixture. The alloying element content in the hexagonal C40 Mo(1−x)MexSi2 phase was nearly constant at a level of about 12 at.% for all starting compositions. In contrast, the content of the alloying elements in the tetragonal phase is considerably lower (around 4 at.%) and increases slightly as the Me content in the starting mixture is increased.

scholarly journals EVALUATING THE EFFECT OF INDUSTRIAL EFFLUENTS ON CHEMICAL COMPOSITION OF SOIL IN VILLAGE DINGI, DISTRICT HARIPUR

2016 ◽  
Vol 1 ◽  
pp. 13
Author(s):  
K. Asghar ◽  
A. Hussain ◽  
Z. Malik ◽  
A. Asghar ◽  
A. Bibi
Keyword(s):  
Soil Fertility ◽  
Present Report ◽  
Research Work ◽  
Monitoring Program ◽  
Industrial Effluents ◽  
Contributing Factors ◽  
Factors Affecting ◽  
Natural Stream ◽  
Underlying Causes ◽  
The Government

The present report is an outcome of research work conducted in Dingi village, District Haripur in 2012. The research aimed to assess and analyze the effects of industrial effluents on the soil fertility of the village, investigate contributing factors responsible for soil pollution and underlying causes creating the problems. Data analysis revealed that area had problems pertaining to water and soil quality. The key factors affecting soil fertility were the careless discharge of the untreated industrial effluents from Hattar Industrial Estate (HIE) into the natural stream passing through village. The results were compared with the soil standards set by the World Wide Fund for Nature (WWF) and European Committee Commission (ECC) and all of these were exceeding the permissible limits and affecting the soil fertility. The soils were found not fit for agriculture. The investigation highlighted the need to take some effective steps to manage the monitoring program set for checking of industries by the government according to set rules and regulation.

scholarly journals Study on the Evolution of the γ′ Phase and Grain Boundaries in Nickel-Based Superalloy during Interrupted Continuous Cooling

Crystals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1464
Author(s):  
Haiping Wang ◽  
Dong Liu ◽  
Jianguo Wang ◽  
Yanhui Yang ◽  
Haodong Rao ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
Short Distance ◽  
Creep Property ◽  
Maximum Amplitude ◽  
Matrix Diffusion ◽  
Cooling Rates ◽  
Continuous Cooling ◽  
Nickel Based Superalloy ◽  
The Matrix ◽  
Solute Atoms

The formation of the irregular γ′ precipitates in the nickel-based superalloy Waspaloy was investigated during the continuous cooling, which is relevant to the cooling rates and interrupted temperature. The morphology of the γ′ precipitates was observed to change from a dispersed sphere to the flower-like one with the decreasing of the cooling rates. It was found that there are three modes of transportation of the solute atoms involved in relation to the γ′ precipitates: dissolution from the small γ′ precipitates to the γ matrix, diffusion to the large γ′ precipitates from the matrix, and the short distance among γ′ precipitates close to each other. Meanwhile, the slower cooling rates tend to result in the serrated grain boundaries, and the wavelength between successive peaks (λ) and the maximum amplitude (A) are larger with the decreasing of the cooling rates. The content of the low ΣCSL boundaries increases with the decreasing of the cooling rates, which is of great benefit in improving the creep property of the Waspaloy.

Building information modelling (BIM) and the return on investment: a systematic analysis

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Apeesada Sompolgrunk ◽  
Saeed Banihashemi ◽  
Saeed Reza Mohandes
Keyword(s):  
Construction Industry ◽  
Return On Investment ◽  
Research Work ◽  
Value Drivers ◽  
Productivity Improvement ◽  
Building Information Modelling ◽  
Content Type ◽  
Factors Affecting ◽  
Information Modelling ◽  
Building Information

Purpose The purpose of this study is to identify and analyse the key measurable returning factors, value drivers and strategic benefits associated with building information modelling (BIM) return on investment (ROI). The findings of this study provide researchers and practitioners with up-to-date information in formulating appropriate strategies to quantify the monetary value of BIM. The suggested research agenda provided would also advance what is presently a limited body of knowledge relating to the evaluation of BIM ROI. Design/methodology/approach To fill the identified gap, this study develops a comprehensive systematic review of mainstream studies on factors affecting BIM ROI published from 2000 to 2020. A total of 23 academic records from different sources such as journals, conference proceedings, dissertation and PhD theses were identified and thoroughly reviewed. Findings The reported BIM ROI ranged greatly from −83.3% to 39,900%. A total of 5 returning factors, namely, schedule reduction and compliance, productivity improvement, request for information reduction, rework reduction and change orders reduction were identified as the most commonly reported factors that influence BIM ROI. Four quantification techniques including general assumptions-based theoretical model, perceived BIM ROI based on survey, factors affecting BIM ROI with no reported ROI and quantified BIM ROI based on a case study were observed and pointed out in the review, together with their limitations. Finally, three major gaps were raised as the lack of consideration on the likelihood of BIM assisting in a construction project, intangible returning factors influencing BIM-based projects and industry standards in benchmarking BIM ROI. Practical implications The outcomes of this study would assist practitioners by providing the current evaluation techniques that address the limitations with BIM investment and present issues relating to the economic evaluation of BIM in the construction industry. It is also expected that presenting a deeper and wider perspective of the research work performed until now will direct a more focussed approach on productivity improvement efforts in the construction industry. Originality/value This study identifies and analyses the key measurable returning factors, value drivers and strategic benefits associated with BIM ROI on an industry scale rather than a particular organisation or a project scale.

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