VHCF of the 3D-Printed Aluminum Alloy AlSi10Mg
Round 1
Reviewer 1 Report
This paper presented the very high cycle fatigue tests and SEM investigation of fracture surface results of hot-rolled and SLM aluminum alloys. The SLM aluminum alloys have significant lower fatigue strength due to the crack initiation associated with large pores and bad meld regions during the laser sintering process. The technical content is good, but the writing needs substantial improvement, especially in the Abstract, Introduction, and Materials and Methods sections.
Abstract needs to be rewritten. Most sentences have been used to introduce the topic instead of presenting the research results.
VHCF(VHCF) properties, spell out VHCF when it appears the first time.
"Such design strategy allows gaining mass up several tens of percent." Citation for the number? Should it be mass reduction instead of gaining mass?
Figure 2-a is the numerical simulation of the resonant frequency of the whole system. Why not a frequency plot is not shown in Fig 2-a?
"The fatigue strength at 107 and 109 is about 40 MPa for hot-144 rolled alloy and about 30 MPa for SLM one." does not match those observed in Fig. 7.
English needs to be improved in many areas, a few examples:
“additive technology production” instead of additive manufacturing
“gain the weight save" instead of save weight
“superior (to)”, “was produces”
“elastic module” instead of elastic modulus;
Young's modules (modulus)
Author Response
Comment: Abstract needs to be rewritten. Most sentences have been used to introduce the topic instead of presenting the research results.
Answer: Abstract is rewritten
Comment: "Such design strategy allows gaining mass up several tens of percent." Citation for the number? Should it be mass reduction instead of gaining mass?
Answer: This is the translation error, such a strategy reduces the mass.
Comment: Figure 2-a is the numerical simulation of the resonant frequency of the whole system. Why not a frequency plot is not shown in Fig 2-a?
Answer: Figure 2 shows a qualitative picture of the realized vibration mode when the sample breaks, in particular, indicates its existence within the given structure in the specified frequency range (19500 - 20500 Hz), Fig. 2-b shows the frequency graph. The paper considers 2 limiting states: a system with an intact sample entering resonance at 20 kHz and a system with a completely destroyed sample (divided into two halves) at 19800 Hz. In this paper, numerical simulation of a gradual decrease in the resonant frequency as a crack propagates in the sample is not expected; therefore, a numerical solution in the form of a frequency graph is not given.
Comment: "The fatigue strength at 107 and 109 is about 40 MPa for hot-144 rolled alloy and about 30 MPa for SLM one." does not match those observed in Fig. 7.
Answer: The word "difference" is missing. The decrease in fatigue strength at 107 and 109 loading cycles is about 40 MPa for hot-rolled and about 30 MPa for printed.
Comment: English needs to be improved in many areas, a few examples:
“additive technology production” instead of additive manufacturing
“gain the weight save" instead of save weight
“superior (to)”, “was produces”
“elastic module” instead of elastic modulus;
Young's modules (modulus)
Answer: The errors are corrected.
Reviewer 2 Report
The authors present an interesting comparison of the VHCF properties of hot-rolled and SLM aluminum specimens. Two different alloys were used: an Al-Cu-Mg wrought alloy and a typical AlSi10Mg SLM alloy. Generally, the conclusions are supported by the results, but some issues are drawn to the attention of the authors:
-Generally speaking, most of the comparative SLM literature compares the properties of specimens made by traditional technologies and additive manufacturing methods using the same alloy system. For example, AlSi10Mg is generally compared when it is manufactured by casting and SLM (for example: Qian Yan, Bo Song, Yusheng Shi: Comparative study of performance comparison of AlSi10Mg alloy prepared by selective laser melting and casting, Journal of Materials Science & Technology, Volume 41, 2020, pp. 199-208, https://doi.org/10.1016/j.jmst.2019.08.049.) Can the authors address shortly why Al-Cu-Mg wrought alloy and AlSi10Mg were compared?
-Grammatical errors and typos should be corrected.
-Before using the abbreviation VHCF, please define it.
-When the results presented in Figure 7 are explained, it is written in lines 144 and 145 that "The fatigue strength at 107 and 109 is about 40 MPa for hot-rolled alloy and about 30 MPa for SLM one." This statement is not reflected by the results presented in Figure 7.
-The caption of Figure 9 states that "The fracture surface of hot-rolled aluminum alloy specimen with (a) surface and (b) sub-surface crack initiation." is presented. However, the same sample is shown at different magnifications.
-The fracture surfaces are analyzed in detail with the aid of SE SEM images, which provide information about the surface topology and morphological features. It would be helpful to present backscattered electron images and implementing EDS elemental analysis would provide information about compositional differences across sample surfaces.
Author Response
Comment: Generally speaking, most of the comparative SLM literature compares the properties of specimens made by traditional technologies and additive manufacturing methods using the same alloy system. For example, AlSi10Mg is generally compared when it is manufactured by casting and SLM (for example: Qian Yan, Bo Song, Yusheng Shi: Comparative study of performance comparison of AlSi10Mg alloy prepared by selective laser melting and casting, Journal of Materials Science & Technology, Volume 41, 2020, pp. 199-208, https://doi.org/10.1016/j.jmst.2019.08.049.) Can the authors address shortly why Al-Cu-Mg wrought alloy and AlSi10Mg were compared?
Answer: In this work, we used a promising method for assessing fatigue strength using a fundamentally new loading system. Due to the novelty of the experimental methods, the comparison was carried out for a family of aluminum alloys with close quasi-static mechanical characteristics. The new research method makes it possible to evaluate the properties of the microstructural state, which, according to the authors, is extremely important for materials obtained by layer-by-layer sintering. In connection with the above, a comparison of the classical and new technologies for creating materials was carried out on alloys of different chemical composition. The paper shows that the integral (quasi-static) characteristics do not allow to fully ensure the safe prediction of the fatigue strength of materials.
Comment: Grammatical errors and typos should be corrected.
Answer: The errors are corrected.
Comment: Before using the abbreviation VHCF, please define it.
Answer: Very high cycle fatigue.
Comment: When the results presented in Figure 7 are explained, it is written in lines 144 and 145 that "The fatigue strength at 107 and 109 is about 40 MPa for hot-rolled alloy and about 30 MPa for SLM one." This statement is not reflected by the results presented in Figure 7.
Answer: This issue is commented on above, the word “difference” in the fatigue strength is 40 and 30 MPa, respectively, for the indicated durability.
Comment: The caption of Figure 9 states that "The fracture surface of hot-rolled aluminum alloy specimen with (a) surface and (b) sub-surface crack initiation." is presented. However, the same sample is shown at different magnifications.
Answer: For this sample, multiple nucleation of fatigue cracks takes place. Figure 9 shows a sample in which two nucleation mechanisms are implemented. In the process of loading, two centers were formed: one under the surface, and the other on the surface. It is these foci that are shown in the Figure 9.
Comment: The fracture surfaces are analyzed in detail with the aid of SE SEM images, which provide information about the surface topology and morphological features. It would be helpful to present backscattered electron images and implementing EDS elemental analysis would provide information about compositional differences across sample surfaces.
Answer: Thank you for your valuable advice, such a study is certainly very useful for understanding the physics of the destruction process. The authors used this approach to analyze the fracture surfaces of a titanium alloy and plan to apply it to this aluminum alloy when studying the physics of the fracture process.
Reviewer 3 Report
The paper titled ‘VHCF of the 3D Printed Aluminum Alloy AlSi10Mg’ demonstrates the fatigue properties of SLM manufactured components. The author has compared the fatigue properties of additively manufactured alloy with the traditional hot rolled alloy. The overall structure of the paper is good. However, several grammatical mistakes need to be rectified before acceptance. Some of the mistakes are given as follow:
Introduction
1. Line 26: Such design strategy allows gaining mass up several tens of percent. The term gaining is inappropriate. Additive manufacturing is known for reducing weight of the component. Not the other way.
2. Line 34: the melt zone is mistyped as meld zone.
3. Line 55: Three-stage diagram of metal fatigue 55 with bifurcation regions and bimodal life distribution on mesoscale: HCF, VHCF. Sentence is unclear. What does author want to tell here?? Kindly modify the sentence so that readers can understand.
4. Line 61: Additive manufacturing or 3D printing are the appropriate words that can be used. The author has written 3D build up which is incorrect.
5. Line 61: Is it possible to use VHCF testing methods for express analysis of the additive technology and what is the inspection parameters could be? What is ‘Express Analysis’??
6. Some recent research works related to this topic is worth citing in the introduction section:
https://doi.org/10.1016/j.addma.2021.102326
https://doi.org/10.1016/j.addma.2022.103052
https://doi.org/10.3390/ma15227954
Materials and Methods
7. Line 110: What do you mean be particles has small satellite??
Results and Discussions
8. Line 187: The neighboring packages do not show and priceable features, such as quasi-ductile zones, in translon. Too many grammatical mistakes in the sentence. What is priceable features??, quasi-ductile zones?? and translon?
Author Response
Introduction
Comment: Line 26: Such design strategy allows gaining mass up several tens of percent. The term gaining is inappropriate. Additive manufacturing is known for reducing weight of the component. Not the other way.
Answer: The sentence is corrected.
Comment: Line 34: the melt zone is mistyped as meld zone.
Answer: The sentence is corrected.
Comment: Line 55: Three-stage diagram of metal fatigue 55 with bifurcation regions and bimodal life distribution on mesoscale: HCF, VHCF. Sentence is unclear. What does author want to tell here?? Kindly modify the sentence so that readers can understand.
Answer: The sentence is corrected.
Comment: Line 61: Additive manufacturing or 3D printing are the appropriate words that can be used. The author has written 3D build up which is incorrect.
Answer: The sentence is corrected.
Comment: Line 61: Is it possible to use VHCF testing methods for express analysis of the additive technology and what is the inspection parameters could be? What is ‘Express Analysis’??
Answer: According to the preliminary results obtained, the selected method can be used to carry out such tests. The ultra-high-cycle fatigue test method (HHTF) allows loading at a frequency of 20 kHz, which significantly reduces the experiment time. So, for example, for tests based on 107 cycles, about 15 minutes are required. Express analysis allows you to build an experimental fatigue curve based on 107 cycles in less than a day. The resulting fracture surfaces make it possible to evaluate the quality of the formed microstructure and determine sintering defects. The obtained experimental data can be used throughout the day to "adapt" the algorithms for constructing samples or products. Thus, the proposed method can really be called express analysis.
Materials and Methods
Comment: Line 110: What do you mean be particles has small satellite??
Answer: A small satellite is meant an attached small particle, the size of which is much smaller than the main one, but which disrupts the geometry of the powder and can potentially lead to negative effects during subsequent sintering.
Results and Discussions
Comment: Line 187: The neighboring packages do not show and priceable features, such as quasi-ductile zones, in translon. Too many grammatical mistakes in the sentence. What is priceable features??, quasi-ductile zones?? and translon?
Answer: We mean not packages, but areas. The crack propagation rate decreases in areas where plastic deformation occurs at various scale levels. The text points to the fact that the fracture surface consists of fundamentally different sections, those where traces of plastic deformation are observed and those where it is not observed.
Round 2
Reviewer 3 Report
It can be accepted
