Effect of Welding Sequence and the Transverse Geometry of the Weld Overlay on the Distribution of Residual Stress in the Weld Overlay Repair of T23 Tubes

Round 1

Reviewer 1 Report

Dear Authors,

I have reviewed your paper "Effect of welding sequence and the transverse geometry of the weld overlay on the distribution of residual stress in the weld overlay repair of T23 tubes", which was submitted to Materials journal.

The paper fulfills aims and scope of the journal. I have some sugestions, which are listed below.

General remarks:

• Your References list have to be rebulit. You have to avoid "et al". Th list should include each author names.
• The name of figures should be provided following the template.

Introduction:

• The effect of welding sequence in low-alloy steels has been investigated by other scientiests. It was proved that changing this sequence leads decreasing the number of cracks in water structures welded by covered electrodes. Also, the bead sequence has crucial effect on the microstructures in HAZ (https://doi.org/10.3390/ma12203372). Also, e.g., it was found for MAG welding that there is no influence of the welding sequence on the depth of penetration and depth of HAZ for individual beads (10.3390/ma13245666).
• To improve the quality of repaired structures other methods could be applied as: temper bead welding, additional stitches, hydrophobic substances on the surface of covered electrodes (filler material). Also, the tack welds distribution is crucial or properties of welded joints and their distortion, which could be connected with resudual stresses.
• Please clearly mark the novelty of your work.

Experiments:

• I propose to change the name of this section to "Materials and Experiments", beceause you have described materials too.
• Please add the information about mechanical properties of welded materials.
• Please name the welding method.
• Which type of thermocouples have you used, K-type? How many specimens were performed?
• Table 1 - source of presented values is missing. Have you analyzed the chemical composition? Or the values were taken from literature/standard/manufacturer data? Please mark Fe value as balance. Showing value with four places after comma is mistake
• Figure 2 - please add information about preparation for microscopic testing. From which places this specimen were taken? Natal etching is correct, or should be Nital? Also, have you used any standards' rules? If yes, please add relevant number. Also, the information about used equipment is missing.
• Table 2 - the most important information during welding is heat input values [kJ/mm]. Please add this issue.
• Equations need references.

Simulations:

• Why have you used these sequences (Fig. 6). Please clarify.

Results and Discussions:

• Figure 7 should be mentioned in the tet before it appears in the text.
• There were differences in the simulations and real results. However, you have not discussed potential reasons.
• In this section I cannot find discussion with other articles. Please compare your results with other scintiests. ou should proved the novelty of your work and its advantages.

Conclusions:

• I propose to support conclusions with values from experiments.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

I recommend the article for publication.

Author Response

Thank you for your affirmation！

Reviewer 3 Report

Comments in the attachment.

Comments for author File: Comments.pdf

Author Response

Please see the attachment！

Author Response File: Author Response.pdf

Reviewer 4 Report

REVIEW

on article

Effect of Welding Sequence and the Transverse Geometry of the Weld Overlay on the Distribution of Residual Stress in the Weld Overlay Repair of T23 Tubes

Xin Xiao, Qu Liu, Mengjia Hu, Kejian Li and Zhipeng Cai

SUMMARY.

Corrosion of pipes is the most common cause of failure of water pipelines, oil pipelines, gas pipelines, chemical pipelines. The consequences of the formation of corrosion damage can be in the form of leaks, as well as in the form of environmental disasters (oil spill), or in the form of an explosion (gas leak in a gas pipeline).

The article discusses options for repairing pipes with the imposition of a welded element by forming an area of compressive stress around the hazardous area. The study included experiments and numerical simulation of welding processes to study the distribution of residual stresses during welding in the repaired area with various repair methods. The article discusses drainpipes, but the problem raised is much broader and can be applied in many other industries.

In this regard, the article is devoted to the interesting and important problem of modelling the stress-strain state and assessing the strength of the welded joint of pipelines.

The reference list contains 26 items.

The article is well structured and logically connected.

At the same time, the article has many inaccuracies and shortcomings.

COMMENTS.

1. Line 97. "... The water-wall tube material is T23 low alloy high-strength steel". Give the known analogues of the steel grade.
2. Give the mechanical characteristics of steels T23 and Inconel 82, such as yield strength, ultimate strength, elongation after rupture, impact strength, so that their strength can be compared with the value of residual stresses.
3. Table 1. There is no carbon C, % in the table. 
4. Line 120. "... The structure of the weld overlay is shown in Figure 1c". Rephrase, please. In fig. 1c shows a cross-section of a weld metal pipe. This is misleading with the microstructure shown in Figure 2.
5. Line 178. "... 3.13. D Finite Element Model". 3.1. 3D Finite Element Model will be correct
6. Section 3.1. 3D Finite Element Model. Give the boundary conditions of the problem.
7. The article is missing the Discussion section. In the Discussion section, it is necessary to give a deep analysis of the results obtained and to compare them with the data obtained by other researchers. This will surely attract the readers' attention and strengthen the article.

In general, the article makes a good impression, so I recommend the article for publication after minor corrections.

Author Response

Please see the attachment！

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Dear Authors,

You have answeed my comments. The paper has been improved, and your efforts are appritiate. I propose to publish this paper in this state.

Best regards,
Reviewer

Reviewer 3 Report

Accept.