Evolution of the Microstructure and Mechanical Properties of Friction Stir Welded Ferrite-Martensite DP700 Dual Phase Steel

Subject Areas :

Mahdi  Mahmoudiniya ¹ (Ph.D. Student, School of Metallurgy and Materials Engineering, Iran University of Science and Technology, Tehran, Iran.)
Amir Hossein  Kokabi ² (Professor, Department of Materials Science and Engineering, Sharif University of Technology, Tehran, Iran.)
Massoud  goodarzi ³ (Associate Professor, School of Metallurgy and Materials Engineering, Iran University of Science and Technology, Tehran, Iran.)

Received: 2019-07-25 Accepted : 2019-11-07 Published : 2020-12-21

Keywords: Tensile Properties, Friction Stir Welding (FSW), Ferrite-Martensite Dual-Phase Steel, Martensite Tempering,

Abstract :

In present research, the effect of tool transverse speed on the microstructure and mechanical properties of friction stir welded DP700 dual-phase steel has been studied. Welding process conducted at a rotational speed of 800 rpm and tool transverse speeds of 50 and 100 mm/min. Optical and scanning electron microscopy were used for microstructural examinations, and mechanical properties were evaluated using microhardness measurements and tensile test. Microstructural investigation revealed that the stir zone consists of bainite, acicular ferrite and polygonal ferrite. It was also revealed that the heat-affected zone (HAZ), based on the peak temperature (Tp), can be subdivided into three different regions: 1) inner HAZ, where Tp is higher than Ac3, 2) Middle HAZ, where Tp lies between Ac1 and Ac3, 3) Outer HAZ in which Tp is lower than Ac1. It was also found that the martensite phase tempers in OHAZ and the degree of tempering decreases with the increment of tool transverse speed. This results confirmed by microhardness measurements where the hardness reduction of the softened zone decreased from 28 to 20HV with an increment of tool transverse speed. The highest hardness of the joints corresponded to the stir zone, and its value increased from 345 to 375HV with rising tool transverse speed. Tensile test results showed that the ultimate strength of the joints was lower than the base metal (723MPa) and it increases from 662 to 671MPa with rising tool transverse speed. It was also revealed that increasing transverse speed improves the total elongation by 2.6%.

References:

[1] Y. Granbom, "Structure and mechanical properties of dual-phase steels", Royal Institute of Technology, 2010.

 

[2] ش. خیراندیش و م. اسدی اسدآباد، "دانشگاه علم و صنعت ایران"، چاپ اول، 1394.

 

[3] N. Peranio, Y.J. Li, F. Roters & D. Raabe, "Microstructure and texture evolution in dual-phase steels: Competition between recovery", recrystallization, and phase transformation, Mater. Sci. Eng. A. 527.  4161–4168. doi:10.1016/j.msea.2010.03.028, 2010.

 

[4] M. Shome &  M. Tumuluru, "Welding and Joining of Advanced High Strength Steels (AHSS)". doi:10.1016/C2013-0-16259-9. 2015.

 

[5] P.H.O.M. Alves, M.S.F. Lima, D. Raabe, H.R.Z. Sandim, Laser beam welding of dual-phase DP1000 steel, J. Mater. Process. Technol. vol. 252, pp, 498–510. doi:10.1016/j.jmatprotec.2017.10.008. 2018.

 

[6] H. Ashrafi, M. Shamanian, R. Emadi & N. Saeidi, "Microstructure, Tensile Properties and Work Hardening Behavior of GTA-Welded Dual-Phase Steels", J. Mater. Eng. Perform. vol. 26, pp, 1414–1423. doi:10.1007/s11665-017-2544-7. 2017.

 

[7] P. Eftekharimilani, E.M. Van Der Aa, M.J.M. Hermans & I.M. Richardson, "Microstructural characterisation of double pulse resistance spot welded advanced high strength steel", Sci. Technol. Weld. Join. vol. 22, pp, 545–554. doi:10.1080/13621718.2016.1274848. 2017.

 

[8] R. Nandan, T. DebRoy  & H. K. D. H. K. D. H. Bhadeshia, "Recent advances in friction-stir welding - Process, weldment structure and properties", Prog. Mater. Sci. vol. 53, pp, 980–1023. doi:10.1016/j.pmatsci.2008.05.001. 2008.

[9] T. Mohandas, G. Madhusudan Reddy & B. S. Kumar, "Heat-affected zone softening in high-strength low-alloy steels", J. Mater. Process. Technol. vol. 88, pp, 284–294. doi:http://dx.doi.org/10.1016/S0924-0136(98)00404-X. 1999.

 

[10] V. H. Baltazar Hernandez, S. S. Nayak & Y. Zhou, "Tempering of martensite in dual-phase steels and its effects on softening behavior", Metall. Mater. Trans. A Phys. Metall. Mater. Sci. vol. 42, pp, 3115–3129. doi:10.1007/s11661-011-0739-3. 2011.

 

[11] J. H. Lee, S. H. Park, H. S. Kwon, G. S. Kim &  C. S. Lee, Laser, tungsten inert gas, and metal active gas welding of DP780 steel: Comparison of hardness, tensile properties and fatigue resistance, Mater. Des. vol. 64, pp, 559–565. doi:http://dx.doi.org/10.1016/j.matdes.2014.07.065. 2014.

 

[12] D. Dong, Y. Liu, Y. Yang, J. Li, M. Ma & T. Jiang, "Microstructure and dynamic tensile behavior of DP600 dual phase steel joint by laser welding", Mater. Sci. Eng. A. vol. 594, pp, 17–25. doi:http://dx.doi.org/10.1016/j.msea.2013.11.047. 2014.

 

[13] J. Wang, L. Yang, M. Sun, T. Liu & H. Li, "Effect of energy input on the microstructure and properties of butt joints in DP1000 steel laser welding", Mater. Des.  vol. 90, pp, 642–649. doi:http://dx.doi.org/10.1016/j.matdes.2015.11.006. 2016.

 

[14] J. Wang, L. Yang, M. Sun, T. Liu & H. Li, "A study of the softening mechanisms of laser-welded DP1000 steel butt joints", Mater. Des. vol. 97, pp, 118–125. doi:10.1016/j.matdes.2016.02.071. 2016.

 

[15] W. M. Thomas, E. D. Nicholas, J. C. Needham, M. G. Nurch, P. Temple-Smith & C. Dawes, "Patents on Friction Stir Butt Welding", 1995.

 

[16] R. S. Mishra, P. S. De & N. Kumar, "Friction Stir Welding and Processing", Frict. Stir Weld. Process. doi:10.1007/978-3-319-07043-8. 2014.

 

[17] M. Matsushita, Y. Kitani, R. Ikeda, M. Ono, H. Fujii & Y. ‐D. Chung, "Development of friction stir welding of high strength steel sheet", Sci. Technol. Weld. Join. vol. 16, pp, 181–187. doi:10.1179/1362171810Y.0000000026. 2011.

 

[18] M. P. Miles, J. Pew, T. W. Nelson & M. Li, "Comparison of formability of friction stir welded and laser welded dual phase 590 steel sheets", Sci. Technol. Weld. Join. vol. 11, pp. 384–388. doi:10.1179/174329306X107737. 2006.

 

[19] H. Kokawa, Y. S. Sato & S. Mironov, "Microstructure evolution of metallic materials during friction stir welding", in: H. Fujii (Ed.), Proc. 1st Int. Jt. Symp. Join. Weld., Woodhead Publishing, pp, 5–13. doi:https://doi.org/10.1533/978-1-78242-164-1.5. 2013.

 

[20] K. Chung, W. Lee, D. Kim, J. Kim, K.-H. Chung, C. Kim, K. Okamoto & R.H. Wagoner, "Macro-performance evaluation of friction stir welded automotive tailor-welded blank sheets: Part I – Material properties", Int. J. Solids Struct. vol. 47, pp, 1048–1062. doi:10.1016/j.ijsolstr.2009.12.022. 2010.

 

[21] K. Dehghani & A. Chabok, "Dependence of Zener parameter on the nanograins formed during friction stir processing of interstitial free steels", Mater. Sci. Eng. A. vol. 528, pp, 4325–4330.doi:https://doi.org/10.1016/j.msea.2011.02.06. 2011.

 

[22] Y. D. Chung, H. Fujii, R. Ueji & K. Nogi, "Friction stir welding of hypereutectoid steel (SK5) below eutectoid temperature", Sci. Technol. Weld. Join. vol. 14, pp, 233–238. doi:10.1179/136217109X415901. 2013.

 

[23] H. G. Tehrani-Moghadam, H. R. Jafarian, M. T. Salehi & A. R. Eivani, "Evolution of microstructure and mechanical properties of Fe-24Ni-0.3C TRIP steel during friction stir processing", Mater. Sci. Eng. A. vol. 718, pp, 335–344. doi:10.1016/j.msea.2018.01.126. 2018.

 

[24] ASTM Standard E 8: Standard test methods for tension testing of metallic materials, 03.01., ASTM, 2000.

 

 [25] ر. پوریامنش و ک. دهقانی "مطالعه ریزساختار و سختی جوش اصطکاکی اغتشاشی فولاد در حضور ذرات اکسید تیتانیوم " فرایندهای نوین در مهندسی مواد، دوره دوازدهم، شماره سوم، سال 1397 .

[26] S. Ragu Nathan, V. Balasubramanian, S. Malarvizhi & A. G. Rao, "Effect of Tool Shoulder Diameter on Stir Zone Characteristics of Friction Stir Welded HSLA Steel Joints", Trans. Indian Inst. Met. vol. 69, pp, 1861–1869. doi:10.1007/s12666-016-0846-3. 2016.

 

 

[27] S. Mironov, Y. S. S. Sato, S. Yoneyama, H. Kokawa, H. T. T. Fujii & S. Hirano, "Microstructure and tensile behavior of friction-stir welded TRIP steel", Mater. Sci. Eng. A. vol. 717, pp, 26–33. doi:10.1016/j.msea.2018.01.053. 2018.

 

[28] H. Das, K. J. Lee & S. T. Hong, "Study on Microtexture and Martensite Formation of Friction Stir Lap-welded DP 590 Steel within A1to A3Temperature Range", J. Mater. Eng. Perform. vol. 26, pp, 3607–3613. doi:10.1007/s11665-017-2780-x. 2017.

 

[29] M. Aksoy, "Effect of initial grain size on microstructure and toughness of intercritical heat-affected zone of a low carbon steel", vol. 286, pp, 289–297. 2000.

 

[30] S. B. Singh, "Mechanisms of bainite transformation in steels", Phase Transform. Steels. pp, 385–416. doi:10.1533/9780857096104.3.385. 2012.

 

[31] M. Ghosh, K. Kumar & R. S. Mishra, "Friction stir lap welded advanced high strength steels: Microstructure and mechanical properties", Mater. Sci. Eng. A. vol. 528, pp, 8111–8119. doi:10.1016/j.msea.2011.06.087. 2011.

 

[32] M. Xia, E. Biro, Z. Tian & Y. N. Zhou, "Effects of heat input and martensite on HAZ softening in laser welding of dual phase steels", ISIJ Int. vol. 48, pp, 809–814. doi:10.2355/isijinternational.48.809. 2008.

 

[33] M. Ghosh, M. Hussain & R. K. Gupta, "Effect of welding parameters on microstructure and mechanical properties of friction stir welded plain carbon steel", ISIJ Int. vol. 52, pp, 477–482. doi:10.2355/isijinternational.52.477. 2012.

 

[34] V. C. Shunmugasamy, B. Mansoor, G. Ayoub & R. Hamade, "Friction Stir Welding of Low-Carbon AISI 1006 Steel: Room and High-Temperature Mechanical Properties", J. Mater. Eng. Perform. vol. 27, pp, 1673–1684. doi:10.1007/s11665-018-3280-3. 2018.

 

[35] S. K. Panda, M. L. Kuntz & Y. Zhou, "Finite element analysis of effects of soft zones on formability of laser welded advanced high strength steels", Sci. Technol. Weld. Join. vol. 14, pp, 52–61. doi:10.1179/136217108X343920. 2009.

 

[36] Q. Sun, H.-S. Di, J.-C. Li & X.-N. Wang, "Effect of pulse frequency on microstructure and properties of welded joints for dual phase steel by pulsed laser welding, Mater". Des. vol. 105, pp, 201–211. doi:http://dx.doi.org/10.1016/j.matdes.2016.05.071. 2016.

 

[37] A. Tiziani, P. Ferro, R. Cervo & M. Durante, "Effects of different welding technologies on metallurgical anf mechanical properties of DP600 steel welded joints", La Metall. Ital. 2011.