Influence of ICCGHAZ on the Low-Temperature Toughness in HAZ of Heavy-Wall X80 Pipeline Steel

Round 1

Reviewer 1 Report

The influence of ICCGHAZ on impact toughness in the HAZ of 22 mm thick X80 292 weld joint was studied in this paper

decreases the toughness reason is not clear . it need more clarification

Figure 11 : How this is related to the objective of this paper. Authors can explain fig and tables in line with objectives

The novel contribution need to be highlighted

Literature review can be improved  

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

This paper presents the work exploring the effect of temperature on fracture mechanisms and overall toughness in a heat-affected zone of lowC pipeline steel X80. The relevance of this topic is well described in the introduction. The microstructural characterization and fractography are presented along with load-deflection curves analysis. Generally, the experimental procedures, results and interpretation are reasonable and in-depth. But there are some minor revisions are needed to make it right and clear before considering this work for publication.

• The treatment of the base steel X80 performed before the welding should be described to gain a better understanding of the research object.
• There is no explanation on the BF abbreviation (is it supposed to be the bainitic ferrite?).
• The average size of the PAGs in the simulated CGHAZ (Fig 3e) seems to be smaller than that in corresponding zone after welding (Fig 3c). Is this arise from the difference in the appropriate thermal cycles?
• The using of the identical red color for BM and CGHAZ in Fig 5 is somewhat confusing for reader.
• It seems that there is a misprint in Fig 7a caption. Probably the corresponding test temperature is 0°C.
• The scale bars in Fig 8a and Fig 8e are cropped. Moreover, I think that the test temperatures and toughness values can be duplicated into images in Fig 8 for better presentation.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

I have only a few formal comments:

Indicate how the chemical composition of the base material was determined.

Explain how the energy (heat input) of the welding process was determined / calculated? (see table 2).

It should be determined for individual weld layers…

Provide a description of Table 1 on the same page as the table itself.

In Table 2, correct the notation for units at speed (mm.s^-1). In Figures 1b) and 5a, b) the time resp. temperature marked in the same way (T) - differentiate the marking.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 4 Report

(L = Line)

L67: Was there an offset between the inner and outer welding spot?

L70: Please include one short statement, why the Gleeble machine was used. At this point, it was unclear to me.

L77: What are the other dimensions (geometry of the notch)? Did you apply precracking? Later in the manuscript, you talk about the precracked blunting zone. Without a precrack, this makes no sense to me.

Fig. 2a: This distance "4 mm" has an extra line brake.

Section 3.1: This sections is mostly hard to read due to the frequent use of (long) abbreviations.

L104: Did you experimentally determine the phase composition of the feature you call "MA constituent". Is martensite austenite a well-defined assumption or real measurement?

L133-134: Is the minimum acceptance value for the materials toughness only the dissipated energy?

L135: please improve the grammar in "to judge whether ...".

Tab. 3: How did you define the DBTT? Was there a certain energy or something else?

L139-140: From a fracture mechanics point of view, the adequacy for use (or the prove of structural integrity) can not be justified by analayzing the charpy impact behavior (energies and temperatures). The resistance of the material (e.g. KIc) must be larger than the loading (e.g. KI) at a certain temperature. Hence, you must state, that this information is sufficient if you follow some specific guideline.

L147: Please check the usage of embrittlement (noun) and other forms (adjective,...) of this word.

L155: At -45 °C, ... -> Check grammar.

L165: Precrack? See comment above.

L175-187: A real fracture mechanics analysis would be much more appropriate. However, based on the measurements, this is could be OK if you include all measures available after the charpy impact test. Here, lateral elongation is missing.

Fig. 7d: The initiation did not start in the region of ICCGHAZ.

L202-203: Quantitative EDS measurement on a fracture surface is useless. However, qualitative measurements are OK. Please reformulate the sentence: E.g. "A qualitative EDS measurement did not reveal any differences between the particle and the matrix. Combined with the smooth..., it was assumed to be a MA constituent."

L215-216: Brittle crack initiations not only in ICCGHAZ, see Fig 7d.

L222-223: The curves have the same shape, but they are not the same.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

It can be accepted 

Reviewer 4 Report

Thank you for revising the manuscript.