Investigation of microstructure and mechanical properties of welding metal of A516-Gr70 steel in the presence of TiO2 by SAW method

Subject Areas : journal of New Materials

Reza Amini Najafabadi ¹ (Assistant Professor of Materials engineering group, Golpayegan college of engineering, Isfahan university of technology, golpayegan, Iran)
Abbas Asadi ² (MSc Student of Materials engineering group, Golpayegan college of engineering, Isfahan university of technology, golpayegan, Iran)

Received: 2021-03-07 Accepted : 2022-02-07 Published : 2021-11-22

Keywords: Acicular Ferrite, submerged arc welding, A516 steel, TiO2 powder, impact toughness,

Abstract :

The effect of adding TiO2 powder to flux in the submerged arc welding process on the microstructure and mechanical properties of steel ASTM A516-Gr.70 was investigated in this research. Microstructural properties have been studied by using the Optical microscope, Scanning Electron microscope, EDS Elemental analysis and X-ray diffraction. Mechanical properties of welding steels were investigated by tensile, hardness and impact tests. Generally, The microstructural investigation, also exhibited that, increasing of TiO2 content cause to increase acicular ferrite in the structure. It has found that the yield strength, UTS and elongation will not show a significant change by variation of TiO2 powder content, because of the broken samples of the metal base, exhibited the same metal base strength. The yield strength of samples is from 420 MPa to 441 MPa, which is in allowed standard range (at least 260 MPa). Also, it has been observed that the ultimate tensile strength is in 550 MPa to 565 MPa range which conforms to standard values (485-620 MPa). The results of impact test showed that welded metal toughness increased from 80 joules to 128 joules by increasing tiO2 from 0 to 27.54 gr. Also, in the case of weld metal hardness, by increasing of TiO2 from 0 to 27.54 gr, it decreases from 190 to 169 Vickers. The results showed that the use of TiO2 powder leads to improvement of mechanical properties, especially failure resistance in welded metal.

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