A Study of the Dynamic Mechanical Properties of Q460D Steel
Round 1
Reviewer 1 Report
This paper discusses the modeling of ductile fracture under high strain rate conditions considering the triaxial stress state for structural steel. This study points out the importance of considering plastic anisotropy. In the introduction, a sufficient and easy-to-understand explanation of the current state of isotropic yield function research is given. After pointing out the lack of information on the yield function in the structural steel, the material properties at various temperatures and strain rates necessary for the simulation of ductile fracture are evaluated experimentally, and the calculation results are obtained successfully. This work presents important findings in considering high-speed deformation and fracture of steels, and is expected to be of interest to related readers. Supplementary explanation seems necessary for the following points.
(1) Introduction
It seems necessary to explain the yield function in the case of plastic anisotropy. Besides Hill's function, there are so-called Yld2000-2d (Barlet et al., Int. J. Plast., 19 (2003) 1297).
(2) materials
If plastic anisotropy is to be considered, the origin of the material, such as the manufacturing process or the texture or structure, should be indicated. Reproducibility of study results is not guaranteed without these information.
(3) negative strain rate sensitivity due to dynamic strain aging
Carbon steel exhibits a negative strain rate dependence near 300 °C (Barnet et al., ISIJ Int., 37(1997) 697). This model does not consider negative strain rate sensitivity.
(4) strain rate
When the strain rate becomes high (>10^4/s), the deformation mechanism differs (e.g. phonon drag), but isn't it possible to express it with the Johnson-Cook model?
Author Response
Dear reviewer:
Thank you for your decision and constructive comments on my manuscript. We have carefully considered the suggestion of Reviewer and make some changes. We have tried our best to improve and made some changes in the manuscript.
The yellow part that has been revised according to your comments. Revision notes, point-to-point, are given as follows:
- Q: Introduction: It seems necessary to explain the yield function in the case of plastic anisotropy. Besides Hill's function, there are so-called Yld2000-2d (Barlet et al., Int. J. Plast., 19 (2003) 1297).
A: The description of some anisotropic yield criterions has been added in Introduction at line 65~67
- Q: materials: If plastic anisotropy is to be considered, the origin of the material, such as the manufacturing process or the texture or structure, should be indicated. Reproducibility of study results is not guaranteed without these information
A: The information of the material is list in Table 1 and the corresponding description is shown at 201~203.
- Q: negative strain rate sensitivity due to dynamic strain aging :Carbon steel exhibits a negative strain rate dependence near 300 °C (Barnet et al., ISIJ Int., 37(1997) 697). This model does not consider negative strain rate sensitivity.
A: The negative strain rate dependence near 300 °C of Q460D steel was indeed observed in this study, but considering the limitation of material performance tests condition and the independence of each parameter in JC model, the coupling of strain rate and temperature is not analyzed, and this issue will be discussed in the future research.
- Q: Strain rate:When the strain rate becomes high (>10^4/s), the deformation mechanism differs (e.g. phonon drag), but isn't it possible to express it with the Johnson-Cook model?
When the strain rate becomes high, the transformation of the plastic deformation mechanism was observed in this paper. In JC constitutive relation, the yield stress is proportional to the logarithm of the strain rate, and the transformation of the plastic deformation mechanism was not considered. But due to the advantage of JC constitutive relation, it was also applied in the research, and re-expressed based on a previously reported method [107]
- Guo, Z.T.; Shu, K.G.; Gao, B.; Zhang, W., J-C model based failure criterion and verification of Q235 steel(In Chinese). Explosion and Shock Waves 2018, 38, 1325-1332.
Reviewer 2 Report
The paper titled "A Study of Dynamic Mechanical Properties of Q460D Steel" investigates the dynamic mechanical properties of Q460D steel with the aim of assessing its impact resistance in building structures. The study involves material performance tests conducted under varying conditions of temperature, strain rates, and stress states. It employs a hybrid experimental–numerical approach to calibrate modified Johnson–Cook (JC) constitutive relations, a modified JC fracture criterion, and a Lode-dependent fracture criterion. These calibrations are validated through Taylor impact tests, where Q460D steel rods are subjected to increasing impact velocities in a one-stage light-gas gun system, resulting in different failure modes, including mushrooming, tensile splitting, and petalling.
A three-dimensional finite element model is constructed for the Taylor impact tests, and FE simulations are performed using the calibrated material models. The study finds that simulations using the Lode-dependent fracture criterion reasonably predict the failure modes of the Taylor rods. Conversely, the Lode-independent JC fracture criterion significantly underestimates the fracture behavior of the Taylor rods. Furthermore, the paper explores and discusses the effects of anisotropy, strain rate sensitivity, and yield plateau on the Taylor impact FE prediction.
Comment to the authors
1. While the paper is generally well-written, there could be some improvement in the clarity of presentation, particularly in explaining the methodology and results of the Taylor impact tests and finite element simulations.
2. It would be beneficial to discuss the practical implications of the study's findings for building structures or engineering applications. How can this research inform real-world design and construction?
3. What is elemental contribution of QD460D?
4. Why Taylor impact tests?
5. What is quasi-static 178 tensile tests?
6. What is split Hopkinson pressure bar
seems fine
Author Response
Dear reviewer:
Thank you for your decision and constructive comments on my manuscript. We have carefully considered the suggestion of Reviewer and make some changes. We have tried our best to improve and made some changes in the manuscript.
The yellow part that has been revised according to your comments. Revision notes, point-to-point, are given as follows:
- Q: While the paper is generally well-written, there could be some improvement in the clarity of presentation, particularly in explaining the methodology and results of the Taylor impact tests and finite element simulations.
A: The detailed descriptions of the methodology and results of the Taylor impact tests and finite element simulations are shown at line 382~385, 409~413, line 423~425 and 442~446 respectively
- Q: It would be beneficial to discuss the practical implications of the study's findings for building structures or engineering applications. How can this research inform real-world design and construction?
A: Q460 is a commonly used steel type in building structures, and widely used in stadium structure such as Bird’s Nest Olympic Stadium. Due to the challenges of attacks such as Russia-Ukraine conflict and 911 terrorist attacks, there is an urgent need for research on Q460 steel dynamic material properties. The corresponding discussion is shown at line 33~35.
- Q: What is elemental contribution of QD460D?
A: The information of the material is list in Table 1 and the corresponding description is shown at line 201~203.
- Q: Why Taylor impact tests?
A: During the Taylor tests, very large and even extreme deformation may develop in a very short time and thus giving birth to high strain rate and high temperature increase. Meanwhile, the stress state is also very rich. All these characteristics make Taylor impact test a benchmark role in identifying the validity of the present material models and the corresponding calibration procedures. The corresponding description is shown at line 134~149
- Q: What is quasi-static 178 tensile tests?
A: The strain rate range of quasi-static is from 10-5~10-1s-1. In this paper, the quasi-static tensile tests were conducted by using a SHIMADZU AG-X plus electronic universal testing machine, and the specimen, The tensile speed was 2 mm/min, and the gauge length was 25 mm. The specimen dimensions are shown in Fig. 1(a).
- Q: What is split Hopkinson pressure bar
A: The SHPB test was conducted using the SHPB apparatus shown in Fig. 4. The apparatus mainly included a striker bar, an incident bar, a transmitter bar and an absorber bar. All these bars were made of 18Ni (350) high-strength steel and had a diameter of 12 mm. The length of the striker bar was 300 mm, and lengths of the other bars were all 1000 mm. The specimens had an 8-mm diameter and a 6-mm height, as shown in Fig. 1(c). And a simplified schematic of SHPB is shown as follow.
Reviewer 3 Report
I have reviewed the manuscript titled "A Study of Dynamic Mechanical Properties of Q460D Steel" and I think this paper is suitable for this journal. The paper is well-organized and the methodology is very well established. Authors have provided a comprehensive theoretical analysis, supported by experimental data. The contribution of this paper to the construction industry is also significant, as it provides insight into a practical issue. However, the manuscript needs some moderate revisions before it can be published.
1- The literature review is good, but it needs to be streamlined to be more focused on recent developments and proposed methods on the topic. There are many papers, recently published with the same concern. Please make sure you update the literature review with more recently published papers on the topic. Following manuscripts are highly recommended:
Ø Jiang, J., Ye, M., Chen, L. Y., Zhu, Z. W., & Wu, M. (2023). Study on static strength of Q690 built-up K-joints under axial loads. Structures, 51, 760-775. doi: https://doi.org/10.1016/j.istruc.2023.03.034
Ø Tian, L., Li, M., Li, L., Li, D., & Bai, C. (2023). Novel joint for improving the collapse resistance of steel frame structures in column-loss scenarios. Thin-Walled Structures, 182, 110219. doi: https://doi.org/10.1016/j.tws.2022.110219
Ø Huang, H., Yao, Y., Liang, C., & Ye, Y. (2022). Experimental study on cyclic performance of steel-hollow core partially encased composite spliced frame beam. Soil Dynamics and Earthquake Engineering, 163, 107499. doi: https://doi.org/10.1016/j.soildyn.2022.107499
2- The theoretical implications of the investigation in the design should be discussed in more detail.
4- The discussion section should be better to more explicit in linking the findings to the literature and the research question. Otherwise it will be more like a technical report. A revision in the discussion is highly recommended.
5- Please provide more details from the material (the standard, microstructure, the manufacturing history and so on).
6- Is this high amount of striations in figure 3b normal and to be expected?
7- Please elaborate on the errors of the measurements. For instance, there is no error bar in Figure 5, makes me wonder if these changes are just some scattering in measurements?
8- Can you please elaborate further (discuss) on the work-softening phenomenon in Figure 6?
9- Adding scale bar to Figure 10 is very useful.
10- In Figure 15, most samples have fractured NOT in the middle. Why?
11- Three mentioned phenomena (mushrooming, tensile splitting, and 635 petalling failure modes) should be properly introduced to readers.
Author Response
Dear reviewer:
Thank you for your decision and constructive comments on my manuscript. We have carefully considered the suggestion of Reviewer and make some changes. We have tried our best to improve and made some changes in the manuscript.
The yellow part that has been revised according to your comments. Revision notes, point-to-point, are given as follows:
- Q : The literature review is good, but it needs to be streamlined to be more focused on recent developments and proposed methods on the topic. There are many papers, recently published with the same concern. Please make sure you update the literature review with more recently published papers on the topic. Following manuscripts are highly recommended:
A: The literature has been appropriately streamlined and the recommended manuscripts has been referenced at line 121 ~ 126.
- Q: The theoretical implications of the investigation in the design should be discussed in more detail.
A: The theoretical implications of the investigation in the design has been discussed at line 134~149, and any other theoretical implications can be seen in our previous research such as ref.[61], [77], [79].
- Q: The discussion section should be better to more explicit in linking the findings to the literature and the research question. Otherwise it will be more like a technical report. A revision in the discussion is highly recommended.
A: In the discussion section, the effect of anisotropy, strain rate sensitivity and yield plateau on the Taylor impact FE predictions were explored and analyzed. Firstly, the hill48 yield criterion was applied in the analysis of anisotropy, and the literature review about yield stress has been summarized in the third paragraph of the introduction. Secondly, the analysis of strain rate sensitivity and yield plateau is corresponding to the modification of the strain rate term and strain hardening term in material dynamic model, and the corresponding literature review is summarized in the fifth paragraph of the introduction. Finally, the discussion section is also an in-depth analysis based on the key content of the manuscript, and extrude the subject. Hence, the discussion section is interconnected with the introduction section.
- Q: Please provide more details from the material (the standard, microstructure, the manufacturing history and so on).
A: The information of the material is list in Table 1 and the corresponding description is shown at 201~203.
- Q: Is this high amount of striations in figure 3b normal and to be expected?
A: Oscillations are evident in stress–strain data at the highest strain rate, which is a very common phenomenon caused by the initial data being obtained while the system is not at equilibrium.
- Q: Please elaborate on the errors of the measurements. For instance, there is no error bar in Figure 5, makes me wonder if these changes are just some scattering in measurements?
A: The measurement error has little effect on the fitting results of strain parameter C, so it is not discussed profoundly in this paper
- Q: Can you please elaborate further (discuss) on the work-softening phenomenon in Figure 6?
A: The thermal softening phenomenon means that the hardness, strength and toughness of materials will becoming softer, easier to bend, and easier to stretch with the temperature increasing, the corresponding description can be seen in line 261~262 and ref [105].
- Q: Adding scale bar to Figure 10 is very useful.
A: Figure 10 is exported by MatchID software and hardly to add scale in it, we will notice this recommendation in future research
- Q: In Figure 15, most samples have fractured NOT in the middle. Why?
A: At high temperatures and high strain rates, some subtle machining errors can also lead to the offset of the fracture position, which is also a normal phenomenon in the test.
- Q: Three mentioned phenomena (mushrooming, tensile splitting, and 635 petalling failure modes) should be properly introduced to readers.
A: The expatiation of mushrooming, tensile splitting, and petalling failure modes has been added in line 409~413,and line 423~425, much deeper description can be found in our previous research [106]
Round 2
Reviewer 1 Report
The manuscript is revised adequately.
Reviewer 3 Report
Thanks for the revision. The revised manuscript is acceptable.
