Microstructure and Properties of Nonlinear Lap Joint of 6061 Aluminum Alloy by Friction Stir Welding

Round 1

Reviewer 1 Report

Title: Microstructure and Properties of Nonlinear Lap Joint of 6061 Aluminum Alloy by Friction Stir Welding

·       Abstract:  Why does the accumulation of welding material depend on the radius?

·       Did you use strain gauge for the tensile tests?

·       Figure 4:  How did you categorize different microstructural regions? 

·       What is the effect of radius on the size of the different microstructural regions?

·       ‘..dominant grain size distribution on the inner side is around 7μm-8μm..’:What does it mean?

·       There is almost no effect of radius on the microhardness and shear strength, Figures 9 and 10.    

·       Please expand on the change of fracture mode with the radius of the joints. 

·       Conclusion 4 has to be changed.      

 

English can be amended.   

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

In the paper, the authors investigated the mechanical properties and microstructure of FSWed lap joints of AW-6061 aluminium alloys. The authors focused on the effect of corner radius on the formability and mechanical properties of the joints.

I evaluate the reviewed article positively in terms of the topic of research and the essence of the information provided. The article is quite well written and structured. I have following remarks to the manuscript, which need to be addressed before its publication.

In the Introduction section the authors presented the results of the review of only five articles [16-20] concerning the FSW of AW-6061 aluminum alloy sheet. It is suggested that this section be expanded to include current literature.

Table 2: The method of determining the mechanical parameters should be described in detail.

Table 2: It is physically impossible that yield strength is greater than tensile strength. Authors should use a professional tensile testing machine and samples with standardized dimensions.

section 2, mechanical parameters: How many specimens were tested? How were they cut from sheet metal?

lines 91-93: This is the problem of many studies on FSW. Why were such constant values of tool rotational speed, welding speed, tilt angle and plunge depth used? Were they optimal? The authors changed only the geometrical parameter of welding (corner radius). However, for each corner radius, the required values of the other parameters may be different to ensure optimal joint quality. It is suggested to use some kind of experimental design in research.

Each acronym should be defined on first use and one definition is sufficient. Meanwhile, for example, "FSW" is defined many times, even twice on the same page. Moreover, some acronyms, i.e. IZ, were not defined.

Phases and precipitations mentioned in the lines 168-169 should be indicated in Figure 5b.

section 3.4.: How were the samples cut from the welded plate for tensile testing?

line 351: Why "Data sharing is not applicable to this article."?

The 'Results' section: The results must be discussed with previously published works. The findings and their implications should be discussed in the broadest context possible, and also indicate the applied value of the research.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf