Novel Application Research on Critical High-Temperature Deformation of Low-Lead Brass Alloy

Round 1

Reviewer 1 Report

Please consider revising the manuscript according to the comments listed below.

(1) There are several small mistakes. Please check the whole manuscript again. Some of the mistakes I found are;

Page 1, line 29: "45 wt.% Zn" not "45 wt. Zn"?

Page 1, line 35: "In recent years" not "In recent year"?

Page 3, line 81: "fractured surface" or "fracture surface", not "fractural surface"?

Page 3, line 91: "ED" is not defined. All the abbreviations should be defined when they first appear. The same comment for "YS", "UTS", "UE", and "TE" in Fig. 3, and "EDS" in the caption of Fig. 8.

Page 12, line 254: "60Cu-40Zn alloys" not "60Cu-50Zn alloys"?

Page 12, line 265: "deformation" not "defprmation"?

Page 12, line 286: "intercrystalline" not "iintercrystalline"?

(2) Since many works have been published on the mechanical properties of Cu-Zn alloy with Pb, even at high temperatures, it is quite important to clarify the originality of this work. The description in "Introduction" implies that the originality of this work is the use of novel alloy with lower Pb and adding Fe and Sn. If so, it is recommended to compare the test results with those of Cu-Zn alloy with higher Pb and no Fe and Sn.

(3) The material used in this work is introduced as "Cu-Zn-Pb-Fe-Sn alloy" in "1. Introduction" but as "low-lead Cu-Zn-Pb alloy" in "2. Materials and methods" and as "Cu38Zn3Pb alloy" in captions of tables and figures. This induces serious confusion. Please consider unifying.

(4) In Table 1: What does the range of Pb 1.0~2.0 wt.% imply?

(5) Please depict the direction of extrusion (ED) also in Fig. 2(b). Since the microstructure image is small and unclear, it is difficult to identify Pb on phase boundaries.

(6) In Section 3.1: The word "brittle" usually implies that there is little or no plastic deformation before failure. If there is relatively large non-uniform plastic deformation, we may not call it brittle behavior. Please consider distinguishing "deformation localization" and "brittleness".

(7) In Fig. 3(a): Why there is no linear elastic part in stress-strain relations?

(8) In Fig. 6: What is the primary mechanism to induce a quite large impact toughness over 600°C? Is it caused by the improved ductility?

(9) In Fig. 7: It is difficult for readers to distinguish the transgranular failure and the fracture along the phase boundary only by the micrographs in Fig. 7. More detailed explanations and magnified images, in which the fracture morphology can be identified, are necessary.

(10) In Section 3.2: If the molten Pb in grain boundaries is the primary cause of weakened phase boundary, why the impact brittle behavior appears only in the intermediate temperature range?

Author Response

May 12, 2020

Title: Novel Application Research on Critical High Temperature Deformation of Low Lead Brass Alloy (metals-791374)

Dear Chris Wang,
Assistant Editor, Metals,

Thank you for your email-letter. We appreciate reviewers’ valuable comments regarding our paper. Please find enclosed our detailed response and revised paper.

Thank you very much again.

Yours Sincerely,

Kuan-Jen Chen

Instrument Center, Instrument Development Center, National Cheng Kung University, Tainan 701, TAIWAN 

e-mail: [email protected]

Response to Reviewer’s Comments

Reviewer 1

1. There are several small mistakes. Please check the whole manuscript again. Some of the mistakes I found are;

Page 1, line 29: "45 wt.% Zn" not "45 wt. Zn"?

Page 1, line 35: "In recent years" not "In recent year"?

Page 3, line 81: "fractured surface" or "fracture surface", not "fractural surface"?

Page 3, line 91: "ED" is not defined. All the abbreviations should be defined when they first appear. The same comment for "YS", "UTS", "UE", and "TE" in Fig. 3, and "EDS" in the caption of Fig. 8.

Page 12, line 254: "60Cu-40Zn alloys" not "60Cu-50Zn alloys"?

Page 12, line 265: "deformation" not "defprmation"?

Page 12, line 286: "intercrystalline" not "iintercrystalline"?

Response:

Throughout manuscript has been checked and revised the mistakes.

2. Since many works have been published on the mechanical properties of Cu-Zn alloy with Pb, even at high temperatures, it is quite important to clarify the originality of this work. The description in "Introduction" implies that the originality of this work is the use of novel alloy with lower Pb and adding Fe and Sn. If so, it is recommended to compare the test results with those of Cu-Zn alloy with higher Pb and no Fe and Sn.

Response:

The processing technology for brass that can be directly hot-worked at high temperature is novel. Therefore, this study conducts to high-temperature impact test, clarifying the effect of intermediate-temperature brittleness on the brass is important for academic research. These sentences have been added in the revision paper.

3. The material used in this work is introduced as "Cu-Zn-Pb-Fe-Sn alloy" in "1. Introduction" but as "low-lead Cu-Zn-Pb alloy" in "2. Materials and methods" and as "Cu38Zn3Pb alloy" in captions of tables and figures. This induces serious confusion. Please consider unifying.

Response:

The material used in this study has been uniformed as “Cu38Zn3Pb” throughout manuscript.

4. In Table 1: What does the range of Pb 1.0~2.0 wt.% imply?

Response:

The content of Pb has been revised in the Table 1.

5. Please depict the direction of extrusion (ED) also in Fig. 2(b). Since the microstructure image is small and unclear, it is difficult to identify Pb on phase boundaries.

Response:

The direction of extrusion (ED) and the phase boundary of Pb has been identified in Fig. 2(b).

6. In Section 3.1: The word "brittle" usually implies that there is little or no plastic deformation before failure. If there is relatively large non-uniform plastic deformation, we may not call it brittle behavior. Please consider distinguishing "deformation localization" and "brittleness".

Response:

In general, the displacement of dislocation in metals is easier with an increase in temperature, causing an easier deformation and a high ductility. However, an intermediate-temperature brittleness phenomenon was found on Cu alloys [14]. The impact test confirmed that the Cu38Zn3Pb alloy demonstrates an intermediate-temperature brittleness phenomenon in the range of 400–600 °C. Therefore, the “brittleness” behavior is used to represent the failure of the alloy specimen at specific temperatures. 

7. In Fig. 3(a): Why there is no linear elastic part in stress-strain relations?

Response:

The linear region is shown below figure:

Fig. 3 (a)

8. In Fig. 6: What is the primary mechanism to induce quite large impact toughness over 600°C? Is it caused by the improved ductility?

Response:

The grains size increased at the high temperature (> 600 °C), and the change in the grain boundaries limited the movement of Pb. This result caused large impact toughness by the improved ductility.

9. In Fig. 7: It is difficult for readers to distinguish the transgranular failure and the fracture along the phase boundary only by the micrographs in Fig. 7. More detailed explanations and magnified images, in which the fracture morphology can be identified, are necessary.

Response:

Fracture subsurface of the alloy specimen above 400 °C showed a flat surface which indicated that the fracture mechanism of the alloy specimen corresponded to the transgranular failure. The existence of voids and holes can be observed at 600 °C, and the cracks extend from the grain boundary. Figure 7 has been revised in the revision paper.

10. In Section 3.2: If the molten Pb in grain boundaries is the primary cause of weakened phase boundary, why the impact brittle behavior appears only in the intermediate temperature range?

Response:

The grains size increased at the high temperature, and the change in the grain boundaries limited the movement of Pb. Therefore, the impact brittle behavior appeared only in the intermediate temperature.

Author Response File: Author Response.pdf

Reviewer 2 Report

The metallographic data and related discussion form the basis for an acceptable paper but the manuscript is not acceptable in its present form for the following reasons.

1. The manuscript should be edited by a competent English language editor. Usage is often awkward and contributes to difficulty in understanding.
2. The source or manufacturer of the test materials should be stated in the Materials and Methods section. Also, the manufacturer of the test machine and other pertinent equipment should be stated.
3. The notch tip radius should be stated in the diagram of the impact test specimen design in Figure 1.
4. The stress-strain curves plotted in Figure 3a must be corrected for the test machine stiffness. These data are not acceptable for publication in their present form because they indicate an elastic modulus orders of magnitude lower than that of copper as well as greater elongation than would be determined from gage marks on the gage section of the test samples. It is straightforward to subtract the machine deflection at each load level and present the data as stress vs. plastic strain. 

Author Response

May 12, 2020

Title: Novel Application Research on Critical High Temperature Deformation of Low Lead Brass Alloy (metals-791374)

Dear Chris Wang,
Assistant Editor, Metals,

Thank you for your email-letter. We appreciate reviewers’ valuable comments regarding our paper. Please find enclosed our detailed response and revised paper.

Thank you very much again.

Yours Sincerely,

Kuan-Jen Chen

Instrument Center, Instrument Development Center, National Cheng Kung University, Tainan 701, TAIWAN

e-mail: [email protected]

Response to Reviewer’s Comments

Reviewer 2

1. The manuscript should be edited by a competent English language editor. Usage is often awkward and contributes to difficulty in understanding.

Response:

This manuscript has been edited by English language editor (Wallace academic editing).

2. The source or manufacturer of the test materials should be stated in the Materials and Methods section. Also, the manufacturer of the test machine and other pertinent equipment should be stated.

Response:

The source or manufacturer of the test materials and the test machines have been stated in the materials and methods section.

3. The notch tip radius should be stated in the diagram of the impact test specimen design in Figure 1.

Response:

The notch tip radius has been stated in the Figure 1.

4. The stress-strain curves plotted in Figure 3a must be corrected for the test machine stiffness. These data are not acceptable for publication in their present form because they indicate an elastic modulus orders of magnitude lower than that of copper as well as greater elongation than would be determined from gage marks on the gage section of the test samples. It is straight forward to subtract the machine deflection at each load level and present the data as stress vs. plastic strain.

Response:

In general, the stress-strain curves are presented in the Figure A. However, in order to completely present the high-temperature tensile properties, the original data is presented in this study.

Fig. A

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Thank you for the answers and the revisions of the manuscript according to the reviewer's comments. The revised manuscript is suitable for publication in "Metals".

Author Response

May 15, 2020

Title: Novel Application Research on Critical High Temperature Deformation of Low Lead Brass Alloy (metals-791374)

Dear Chris Wang,
Assistant Editor, Metals,

Thank you for your email-letter. We appreciate reviewers’ valuable comments regarding our paper. Please find enclosed our detailed response and revised paper.

Thank you very much again.

Yours Sincerely,

Kuan-Jen Chen

Instrument Center, Instrument Development Center, National Cheng Kung University, Tainan 701, TAIWAN

e-mail: [email protected]

Response to Reviewer’s Comments

Reviewer 1

Thank you for the answers and the revisions of the manuscript according to the reviewer's comments. The revised manuscript is suitable for publication in "Metals".

Response:

Thank you for reviewers’ valuable comments regarding our paper.

Author Response File: Author Response.pdf

Reviewer 2 Report

The revised version is improved but the author has not appropriately addressed point number 4 in my initial review regarding correcting for grip effects and machine stiffness. The curves labeled as stress - strain in Figures 3 and 5 include grip effects and machine deflection as well as material response. The concave upward region in all curves at the initiation of testing reflects seatinig of the sample and fixtures upon initial loading. The subsequent linear portion of the curves includes machine deflection as well as the elastic response of the samples. Indeed, the apparent elastic modulus in the data of Figures 3 and 5 is roughly 10 GPa whereas the elastic modulus of Cu-base alloys is typically 120 - 130 GPa. The apparent strain at fracture will be over estimated because this apparent strain also includeds machine deflection. 

Correction for this problem is straightforward. Simply construct a straight line representing the machine and sample elastic deflection and then subtract this deflection at each stress from the total deflection. The resulting curves will be stress versus plastic strain. In testing such as done here accurate determination and representation of the modulus is not done given the relative strain insensitivity of this type of test. If the author has any questions and expert on mechanical testing should be consulted.

Author Response

May 15, 2020

Title: Novel Application Research on Critical High Temperature Deformation of Low Lead Brass Alloy (metals-791374)

Dear Chris Wang,
Assistant Editor, Metals,

Thank you for your email-letter. We appreciate reviewers’ valuable comments regarding our paper. Please find enclosed our detailed response and revised paper.

Thank you very much again.

Yours Sincerely,

Kuan-Jen Chen

Instrument Center, Instrument Development Center, National Cheng Kung University, Tainan 701, TAIWAN

e-mail: [email protected]

Response to Reviewer’s Comments

Reviewer 2

The revised version is improved but the author has not appropriately addressed point number 4 in my initial review regarding correcting for grip effects and machine stiffness. The curves labeled as stress-strain in Figures 3 and 5 include grip effects and machine deflection as well as material response. The concave upward region in all curves at the initiation of testing reflects seatinig of the sample and fixtures upon initial loading. The subsequent linear portion of the curves includes machine deflection as well as the elastic response of the samples. Indeed, the apparent elastic modulus in the data of Figures 3 and 5 is roughly 10 GPa whereas the elastic modulus of Cu-base alloys is typically 120 - 130 GPa. The apparent strain at fracture will be over estimated because this apparent strain also includeds machine deflection.

Correction for this problem is straightforward. Simply construct a straight line representing the machine and sample elastic deflection and then subtract this deflection at each stress from the total deflection. The resulting curves will be stress versus plastic strain. In testing such as done here accurate determination and representation of the modulus is not done given the relative strain insensitivity of this type of test. If the author has any questions and expert on mechanical testing should be consulted.

Response:

Thank you for reviewers’ valuable comments. According to reviewers’ suggestion, the Figure 3 has been revised in the revision paper.

Fig. 3(a)

Author Response File: Author Response.pdf

Round 3

Reviewer 2 Report

The addition of the lines on the stress - strain plots of Figure 3 would do more to confuse the issue than correct the problem. It is apparent that my comments in my second review were not fully understood by the author. In particular, the initial grip and fixture seating and the elastic deflection of the load cell are incorrectly labeled.

Again, I strongly recommend that the author identify and contact an expert in tensile testing (perhaps a representative of the testing equipment manufacturer can assist) and learn how to eliminate machine effects and present the tensile curves as stress versus plastic strain.

Author Response

May 21, 2020

Title: Novel Application Research on Critical High Temperature Deformation of Low Lead Brass Alloy (metals-791374)

Dear Chris Wang,
Assistant Editor, Metals,

Thank you for your email-letter. We appreciate reviewers’ valuable comments regarding our paper. Please find enclosed our detailed response and revised paper.

Thank you very much again.

Yours Sincerely,

Kuan-Jen Chen

Instrument Center, Instrument Development Center, National Cheng Kung University, Tainan 701, TAIWAN 

e-mail: [email protected]

Response to Reviewer’s Comments

Reviewer 2

The addition of the lines on the stress - strain plots of Figure 3 would do more to confuse the issue than correct the problem. It is apparent that my comments in my second review were not fully understood by the author. In particular, the initial grip and fixture seating and the elastic deflection of the load cell are incorrectly labeled.

Again, I strongly recommend that the author identify and contact an expert in tensile testing (perhaps a representative of the testing equipment manufacturer can assist and learn how to eliminate machine effects and present the tensile curves as stress versus plastic strain.

Response:

Thank you for reviewers’ valuable comments. According to our previous reports [a, b, c], the similar results also occurred in tensile test. Universal material tester has been calibrated in this study. This stress-strain curve contains the displacement of test system (machine deflection, initial grip, fixture seating), which is more obvious under high temperature tensile test. Therefore, we believe that the stress-plastic strain curves should be presented faithfully, as shown in Figure 3(a) and Fig. 5. We believe that there is no need to change this revision after this modification.

• L. Chang, F. Y. Hung, T. S. Lui, “A new infrared heat treatment on hot forging 7075 aluminum alloy: microstructure and mechanical properties”, Mater. 13 (2020) 1177.
• R. Zhao, F. Y. Hung, T. S. Lui, “Erosion resistance and particle erosion-induced tensile embrittlement of 3D-selective laser melting Inconel 718 superalloy”, Metals 10 (2020) 21
• L. Chang, F. Y. Hung, T. S. Lui, “Study of microstructure and tensile properties of infrared-heat-treated cast-forged 6082 aluminum alloy”, J. Mater. Res. Tech. 8 (1) (2019) 173-179.

Fig. 3(a)

Fig. 5

Author Response File: Author Response.pdf