Transformation of the δ-Ferrite in SS2343 Austenitic Stainless Steel upon Annealing at 1050 °C, 1150 °C and 1250 °C

Round 1

Reviewer 1 Report

In this paper the decomposition of delta-ferrite during annealing at high temperatures 1050-1250 C is considered in details.

 So, as the several annealing temperatures are used in this research, then it is better to correct the title of paper with respect to temperature interval from 1050 to 1250C.

 

Author Response

Response to reviewers' comments (Manuscript ID = metals-1184249):

 

REVIEWER 1:

 

Open Review

(x) I would not like to sign my review report
( ) I would like to sign my review report

English language and style

( ) Extensive editing of English language and style required
( ) Moderate English changes required
(x) English language and style are fine/minor spell check required
( ) I don't feel qualified to judge about the English language and style

 

	Yes	Can be improved	Must be improved	Not applicable
Does the introduction provide sufficient background and include all relevant references?	(x)	( )	( )	( )
Is the research design appropriate?	(x)	( )	( )	( )
Are the methods adequately described?	(x)	( )	( )	( )
Are the results clearly presented?	(x)	( )	( )	( )
Are the conclusions supported by the results?	(x)	( )	( )	( )

Comments and Suggestions for Authors

1. In this paper the decomposition of delta-ferrite during annealing at high temperatures 1050-1250 C is considered in details.
2. So, as the several annealing temperatures are used in this research, then it is better to correct the title of paper with respect to temperature interval from 1050 to 1250C.

 Submission Date

07 May 2021

Date of this review

20 May 2021 07:19:59

 

AD COMMENT 2:

The title was improved according to the suggestion:

Transformation of the δ-ferrite in SS2343 austenitic stainless steel upon annealing at 1050 °C, 1150 °C and 1250 °C

Author Response File: Author Response.pdf

Reviewer 2 Report

The paper under review can be recommended for publication after minor revisions:

1. Why does the title not mention the temperature of 1150 ° C?
2. Rows 127-128: Reference to the literature for this statement is missing.
3. The references to the literature in lines 122 and 138 evoke that the calculations were taken from the mentioned literatures.
4. Explain why N was neglected in the calculations.
5. Row 131: Where is the seven phase equilibrium?
6. Define exactly what f₀ means.
7. Table 2: The values “Mean, Std.Dev. Max, Min”mix ferrite and austenite values ​​together. If necessary, calculate the values separately for ferrite and austenite.
8. It would be useful to compare the amounts of elements (Cr, Ni, Mo) in austenite and δ-ferrite  (Fig.7 ) with the equilibrium values ​​calculated by THERMO-CALC.
9. Indicate how the cumulative concentrations were determined or calculated.
10. It would be appropriate to evaluate the experimental results also with respect to the calculations of equilibria. (δ-ferrite is equilibrium phase at 1250°C according to calculations).

Author Response

REVIEWER 2:

 

Open Review

(x) I would not like to sign my review report
( ) I would like to sign my review report

English language and style

( ) Extensive editing of English language and style required
( ) Moderate English changes required
( ) English language and style are fine/minor spell check required
(x) I don't feel qualified to judge about the English language and style

 

	Yes	Can be improved	Must be improved	Not applicable
Does the introduction provide sufficient background and include all relevant references?	( )	(x)	( )	( )
Is the research design appropriate?	(x)	( )	( )	( )
Are the methods adequately described?	(x)	( )	( )	( )
Are the results clearly presented?	( )	(x)	( )	( )
Are the conclusions supported by the results?	(x)	( )	( )	( )

Comments and Suggestions for Authors

The paper under review can be recommended for publication after minor revisions:

1. Why does the title not mention the temperature of 1150 ° C?
2. Rows 127-128: Reference to the literature for this statement is missing.
3. The references to the literature in lines 122 and 138 evoke that the calculations were taken from the mentioned literatures.
4. Explain why N was neglected in the calculations.
5. Row 131: Where is the seven phase equilibrium?
6. Define exactly what f₀ means.
7. Table 2: The values “Mean, Std.Dev. Max, Min”mix ferrite and austenite values ​​together. If necessary, calculate the values separately for ferrite and austenite.
8. It would be useful to compare the amounts of elements (Cr, Ni, Mo) in austenite and δ-ferrite  (Fig.7 ) with the equilibrium values ​​calculated by THERMO-CALC.
9. Indicate how the cumulative concentrations were determined or calculated.
10. It would be appropriate to evaluate the experimental results also with respect to the calculations of equilibria. (δ-ferrite is equilibrium phase at 1250°C according to calculations).

 

Submission Date

07 May 2021

Date of this review

13 May 2021 15:23:03

 

AD COMMENT 1:

Annealing tests were conducted at 1050 °C, 1150 °C and 1250 °C.

The title and abstract were improved according to the suggestion:

Transformation of the δ-ferrite in SS2343 austenitic stainless steel upon annealing at 1050 °C, 1150 °C and 1250 °C

AD COMMENT 2:

Reference to the literature for this stetement is added:

…were calculated [30] in temperature range 400 – 1600 °C…..

The thermodynamic calculations were performed using the Thermo-Calc Software package 2017a and the database TCFE8:Steels/Fe-Alloys v8.1 [30].

AD COMMENT 3:

For the calculation of  phase diagrams in represented in Figures 1 and 2, Thermo-Calc 2017a Software Package using database TCFE5 for Steels /Fe-alloys V8.1 was used.

AD COMMENT 4:

Nitrogen was not taken into account in the calculation, due to the low content for this type of steel.

AD COMMENT 5:

There is a mistake. In vertical section of the phase diagram have ten phase (equlibria solidification), and five phases considered in calculation

AD COMMENT 6:

f₀ is the initial content of ferrite (as-cast state), f is the content at a certain time and annealing temperature

AD COMMENT 7:

Thank you for the suggestion. Values of mean, std. dev., max., min. calculated together for ferrite and austenite are incorrect. Therefore, they are deleted in the revised manuscript.

AD COMMENT 8:

We agree. but we only wanted to show the solidification phases with the thermodynamic calculation.

AD COMMENT 9:

On Figure 8 are presented the cumulative concentrations of the elements Cr, Ni and Mo in the matrix of austenitic stainless steel, specially for the individual changes in the concentrations of Cr, Ni and Mo in the ferrite and austenite. The cumulative for Cr is calculated as  where V_A and V_F are volume fractions of ferrite and austenite and V_A +V_F =100. Cumulative for Ni and Mo are calculated in the same way.

AD COMMENT 10:

From Figure 2, we can see that at 1250 °C, under equilibrium conditions, there is about 8% ferrite present. At 1250 °C for 5- or 40-min of annealing time, the measured δ-ferrite content is 6.17 and 5.52 vol.%, respectively.

 

Reviewer 3 Report

1. The analysis of the chemical composition of steel was performed experimentally (Table 1), but the accuracy of the method was not specified anywhere.

2. X-ray phase analysis of the material is missing. The article describes the transformation of the δ-ferrite in SS2343 austenitic stainless steel, but the phase characteristics are presented only on the basis of the microstructure. It would be interesting and complementary to present the results of the X-ray phase and structure analysis.

3. fig. 7 and 8 - description a, b, c is missing

Author Response

REVIEWER 3:

 

 

Open Review

(x) I would not like to sign my review report
( ) I would like to sign my review report

English language and style

( ) Extensive editing of English language and style required
( ) Moderate English changes required
(x) English language and style are fine/minor spell check required
( ) I don't feel qualified to judge about the English language and style

 

	Yes	Can be improved	Must be improved	Not applicable
Does the introduction provide sufficient background and include all relevant references?	(x)	( )	( )	( )
Is the research design appropriate?	( )	(x)	( )	( )
Are the methods adequately described?	( )	( )	(x)	( )
Are the results clearly presented?	( )	(x)	( )	( )
Are the conclusions supported by the results?	( )	(x)	( )	( )

Comments and Suggestions for Authors

1. The analysis of the chemical composition of steel was performed experimentally (Table 1), but the accuracy of the method was not specified anywhere.
2. X-ray phase analysis of the material is missing. The article describes the transformation of the δ-ferrite in SS2343 austenitic stainless steel, but the phase characteristics are presented only on the basis of the microstructure. It would be interesting and complementary to present the results of the X-ray phase and structure analysis.
3. fig. 7 and 8 - description a, b, c is missing

 

Submission Date

07 May 2021

Date of this review

21 May 2021 02:02:21

 

AD COMMENT 1:

The chemical composition was analyzed using a quantitative chemical analysis of steel (instruments used: ICP-AES Perkin Elmer, Eltra CS800, Eltra ON), and provided in Table 1. Table 1 is improved; accuracy of the methods is provided (as per element).

 

AD COMMENT 2:

In the study, ferrite fractions were measured with feritscope. The chemical compositions of ferrite and austenite were analyzed using SEM-EDS method. However, we fully agree, that it would be interesting to perform the result of XRD analysis as well.

AD COMMENT 3:

 In the as-cast microstructure, close to edge (Figure 4a) there is the skeletal ferritic network (vermicular), and at the center it becomes lathy (figure 4 c), finer structure. The vermicular is aligned skeletal network. Theirs orientation is along the heat flow direction. The ferrite present is the remnants of the primary and dendrite arms. The lacy morphology is characterized by an interlaced ferrite network oriented along the growth direction. The acicular morphology is a random arrangement of needle-like ferrite distributed in a austenite matrix. The final morphology is globular morphology. It is characterized by ferrite in globules which are randomly distributed in a matrix of austenite.  

Reviewer 4 Report

The paper concerns the transformation of the δ-ferrite in SS2343 austenitic stainless steel upon annealing at 1050 °C and 1250 °C. Presented results and research methodology are interesting however, the novelty of presented results is not clarified. The authors of the publication should clearly present what new findings they have made in relation to other researchers. Only articles that bring new information into the research topic are of interest to potential readers. In my opinion, this manuscript fits more to a technical report rather than a scientific paper.

 

Abstract

1/ “After the annealing, the concentrations of the ferrite-stabilizing elements decrease and, conversely, the amounts of austenite-stabilizing elements increase, by small but significant amounts.” The above sentence is not clear. Please explain the reason for the change in chemical composition

Keywords

2/ Please remove “effectiveness” from the keywords list.

Introduction

3/ Do the equations 1 and 2 refer to wt.% ? It should be specified in the manuscript.

Results and Discussion

4/ The quality of fig. 3 is very low. It should be improved.

5/ The quality of fig. 7 is very low. It should be improved.

6/ Table 2. Do the presented results refer to wt.%? ? It should be specified in the manuscript.

Conclusions

7/ Conclusions are too long.  Authors should present the main findings in the form of points list.

Manuscript title

8/ “Transformation of the δ-ferrite in SS2343 austenitic stainless steel upon annealing at 1050 °C and 1250 °C”

Why the temperature of 1150°C was not included in the manuscript title? The authors present the results for this annealing temperature ...

Author Response

REVIEWER 4:

 

 

Open Review

(x) I would not like to sign my review report
( ) I would like to sign my review report

English language and style

( ) Extensive editing of English language and style required
( ) Moderate English changes required
( ) English language and style are fine/minor spell check required
(x) I don't feel qualified to judge about the English language and style

 

	Yes	Can be improved	Must be improved	Not applicable
Does the introduction provide sufficient background and include all relevant references?	( )	( )	(x)	( )
Is the research design appropriate?	(x)	( )	( )	( )
Are the methods adequately described?	(x)	( )	( )	( )
Are the results clearly presented?	( )	( )	(x)	( )
Are the conclusions supported by the results?	( )	(x)	( )	( )

Comments and Suggestions for Authors

The paper concerns the transformation of the δ-ferrite in SS2343 austenitic stainless steel upon annealing at 1050 °C and 1250 °C. Presented results and research methodology are interesting however, the novelty of presented results is not clarified. The authors of the publication should clearly present what new findings they have made in relation to other researchers. Only articles that bring new information into the research topic are of interest to potential readers. In my opinion, this manuscript fits more to a technical report rather than a scientific paper.

 

Abstract

1/ “After the annealing, the concentrations of the ferrite-stabilizing elements decrease and, conversely, the amounts of austenite-stabilizing elements increase, by small but significant amounts.” The above sentence is not clear. Please explain the reason for the change in chemical composition

Keywords

2/ Please remove “effectiveness” from the keywords list.

Introduction

3/ Do the equations 1 and 2 refer to wt.% ? It should be specified in the manuscript.

Results and Discussion

4/ The quality of fig. 3 is very low. It should be improved.

5/ The quality of fig. 7 is very low. It should be improved.

6/ Table 2. Do the presented results refer to wt.%? ? It should be specified in the manuscript.

Conclusions

7/ Conclusions are too long.  Authors should present the main findings in the form of points list.

Manuscript title

8/ “Transformation of the δ-ferrite in SS2343 austenitic stainless steel upon annealing at 1050 °C and 1250 °C”

9/ Why the temperature of 1150°C was not included in the manuscript title? The authors present the results for this annealing temperature ...

 

Submission Date

07 May 2021

Date of this review

18 May 2021 00:47:32

 

AD GENERAL COMMENT:

The novelty of the manuscript :

Relevant literature sources have been used to place the findings of this study into a relevant scientific framework. Four new literature sources [31-34] are additionally used:

• Allahyari, a.a.; Farhangi, H.; Hadavi, S.M.M. Investigation of aging heat treatment on microstructure and mechanical properties of 316L austenitic stainless steel weld metal. WIT Transactions on Engineering Sciences 2005, 51, 63-71.
• Arnaldo F.J.; Jorge O.; Rodrigo M. Ferrite Quantification Methodologies for Methodologies for Duplex Stainless Steel. J.Aerosp. technol. Mang., São José dos Campos 2016, 8, 375-362.
• Kim, S.H.; Moon, H.K.; Kang, T.; Lee, C.S. Disolution kinetics of delta ferrite in AISI 304 stainless steel produced by strip casting process. Material Science and Engineering 2003, A356, 390-398.
• Gokul, O.S.; Byeong, S.K.;Ho, J.L.; Changheui, J. Evaluation of the thermal aging of δ-ferrite in austenitic stainless steel welds by electrochemical analysis. Scientific reports 2018, 8, 1-17.   

 

A study of literature has shown, that most of the scientific literature on δ–ferrite dissolution states that increasing annealing time and temperature promote the dissolution of δ–ferrite. Our study on δ –ferrite dissolution of austenitic stainless SS2343 has shown, that at 1250°C δ–ferrite fraction is increasing when compared to 1150°C and lower annealing temperatures regardless on annealing time. This is contradictory to the existing literature [31-34] except to the results of reported by Saied on Fe-Cr-Ni austenitic steel [4]. Results of his study clearly show that for the studied Fe-Cr-Ni austenitic steel δ–ferrite dissolution is not decreasing with increasing annealing temperature and time. it is clearly shown In his study, that with temperatures above 1280°C (regardless of annealing time), the content of δ–ferrite increases. Furthermore, first increases in δ–ferrite content are detected as low as at 1200 °C. One can conclude, that the δ–ferrite dissolution dynamically depends on both, temperature and time. A widely accepted assumption, that δ–ferrite dissolution increases with increasing annealing temperature and time is not valid, at least for the Fe-Cr-Ni austenitic steel studied by Saied [4].

In our study, austenitic stainless steel SS2343 has significantly different chemical composition compared to Fe-Cr-Ni austenitic steel studied by other authors [e.g., 4, 31-34]. Based on comparison of Saied [4], and experimentally obtained data of our study, it can be concluded that (i) δ–ferrite dissolution is not monotonically decreasing with increasing annealing temperature and time, and (ii) that the δ–ferrite dissolution should be carefully studied for every individual alloy.

Furthermore, equilibrium (better transient) values of δ–ferrite seems to change or depend (as function of annealing temperature and time) on chemical composition of base alloy. And that was the purpose of present study – determination of δ–ferrite dissolution of the steel SS2343.

 

 

 

 

AD COMMENT 1:

Abstract: In the δ-ferrite after annealing, concentrations of Ni and Mo decrease, and conversely the concentration of Ni increase. All by small, but significant, amounts.

 

AD COMMENT 2:

Expression »Effectiveness« is removed from from the keywords.

AD COMMENT 3:

 A descriptive sentence regarding wt. % is added.

»The Cr_eq and Ni_eq indexes can be estimated with the following equations 1 and 2 [4-6], where contents of elements are given in wt. %:«

AD COMMENT 4:

For the picture quality 3, we do our best to improve image

AD COMMENT 5:

For the picture quality 7, we do our best to improve image

 

AD COMMENT 6:

 Caption of Table 2 is improved: wt. % added.

AD COMMENT 7:

Conclusions are rewritten and shortened. In the revised text, a point list is used as well.

• After annealing at 1150 °C at 5 and 40 min, the content of δ-ferrite was reduced to 5.0 and 2.64 vol.%, respectively. Thus, about 60 or 80 % the δ-ferrite is transformed by annealing.
• After annealing at 1150 °C, the δ-ferrite dissolution and transformation process initiates in secondary arms and progresses also in primary arms, where dendritic network of δ-ferrite tends to break down and spheroidize.
• After annealing at 1250 °C the dissolution of δ-ferrite was only ~50 %. Morphologically is remaining δ-ferrite mostly spherical.
• Concentrations of Cr, Ni and Mo in the δ-ferrite during annealing are diffusion controlled and are approaching towards concentrations in matrix of SS2343.

 

AD COMMENT 8:

 In the δ-ferrite after annealing, concentrations of Ni and Mo decrease, and conversely the concentration of Ni increase. All by small, but significant, amounts. The disollution process is interface diffusion controlled at δ-γ interfaces. The Cr deplition in ferrite increases its instability and enhances its dissolution. Dissolution kinetics was controlled by volume diffusion of Cr, Ni and Mo [23,33].

 

 

 

 

 

AD COMMENTS 9:

The title was improved according to the suggestion:

Transformation of the δ-ferrite in SS2343 austenitic stainless steel upon annealing at 1050 °C, 1150 °C and 1250 °C

 

 

Round 2

Reviewer 4 Report

The manuscript has been sufficiently improved to be published in Metals journal. However, I have one remark: 

Abstract: "In the δ-ferrite after annealing, concentrations of Ni and Mo decrease, and conversely the concentration of Ni increase" The sentence is still not clear. It should be clarified before publication.

Author Response

REVIEWER 4:

 

Open Review

(x) I would not like to sign my review report
( ) I would like to sign my review report

English language and style

( ) Extensive editing of English language and style required
( ) Moderate English changes required
( ) English language and style are fine/minor spell check required
(x) I don't feel qualified to judge about the English language and style

 

	Yes	Can be improved	Must be improved	Not applicable
Does the introduction provide sufficient background and include all relevant references?	( )	(x)	( )	( )
Is the research design appropriate?	(x)	( )	( )	( )
Are the methods adequately described?	(x)	( )	( )	( )
Are the results clearly presented?	(x)	( )	( )	( )
Are the conclusions supported by the results?	( )	(x)	( )	( )

Comments and Suggestions for Authors

The manuscript has been sufficiently improved to be published in Metals journal. However, I have one remark: 

Abstract: "In the δ-ferrite after annealing, concentrations of Ni and Mo decrease, and conversely the concentration of Ni increase" The sentence is still not clear. It should be clarified before publication.

 

AD COMMENT 1:

Abstract: In the δ-ferrite after annealing, concentrations of Cr and Mo decrease, and conversely the concentration of Ni increase. All by small, but significant, amounts.

Since the same mistake appears further in “Results and discussion”, we corrected it also there. This is in “ad comment8”.

AD COMMENT 8:

 In the δ-ferrite after annealing, concentrations of Cr and Mo decrease, and conversely the concentration of Ni increase. All by small, but significant, amounts. The dissolution process is interface diffusion controlled at δ-γ interfaces. The Cr depletion in ferrite increases its instability and enhances its dissolution. Dissolution kinetics was controlled by volume diffusion of Cr, Ni and Mo [23,33].