Investigation of Friction Stir Welding of Stainless Steel Using a Stop-Action-Technique

Abstract:

Especially for aluminium and its alloys friction stir welding (FSW) has become an established welding process. In contrast FSW for steel is still challenging and in basic research. Some reasons are the high price of the tungsten based tools, the durability of the tools and the low welding speeds. For further development of the process, it is necessary to understand the metallurgical changes in the stirred material during welding. In this work, a 4mm thick stainless steel plate (1.4301) was welded with different types of tungsten-alloyed tools. A so called stop-action-technique was used at the end of the weld and the sheet was quenched immediately to prevent metallurgical changes caused by slow cooling. During the process, the temperatures on the top of the welded plate, close to the tool shoulder (10 mm beside the weld centre line) and at the bottom of the plate, directly below the weld centre were measured. On the bottom side, the temperature was also measured 35mm in front of the end of the weld to compare the differences in the cooling rate. The measured peak temperatures ranged from 330°C on top to about 1200°C on the bottom of the specimen. Moreover rotational speed was varied up to 1200 RPM to test the possibility to reduce the process forces and spindle torque. In addition the influences of the welding process parameters on the microstructural changes were investigated. E.g. the average grain size was measured which ranged from 6 to 12 µm in the stirzone.

• Periodical: Advanced Materials Research (Volume 409)
• Pages: 293-298
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.409.293
• Online since: November 2011
• Authors: Christian Pfeiffer, Thomas Weinberger, H. Schröttner, Stefan Mitsche, Norbert Enzinger
• Keywords: Friction Stir Welding (FSW), Microstructure, Steel, Stop Action Technique

References

[1] Thomas, W. M. Nicholas E.D., Needham J.C., Murch M.G. and Templesmith P., Improvements relations of friction welding. PCT/GB92/02203 (1991).

[2] Zettler R., Sheikhi S, dos Santos J.F. and Roos A., Prinzipien/Grundlagen des Reibschweißens. Lehrgang Reibrührschweißen (2005), Geesthacht.

[3] Mueller S., Friction Stir Welding as joining process in the shipbuilding industry. 4. GKSS FSW Workshop 2009, Geesthacht.

[4] Ostersehlte H., Reibrührschweißen in der Luftfahrt. 3. GKSS Workschop Reibrührschweißen (2005), Geesthacht.

[5] Bhadeshia H. K. D. H., and DebRoy T., Critical assessment: friction stir welding of steels, in Science and Technology of Welding and Joining. (2009).

DOI: 10.1179/136217109x421300

[7] Kyffin W.J., Threadgill P.L., Lalvani H. and Wynne B.P., Progress in FSSW of DP 800 High Strengh Automotive Steel. 6th International Symposium on Friction Stir Welding (2006) Thousand Oaks, USA.

[8] Führer.B.; Prozess- und Werkzeugentwicklung für das Rührreibschweißen von Stahl. (2007).

[9] Park S. H .C., Sato Y. S., Kokawa H., Okamoto K. and Inagaki M., Rapid formation of the sigma phase in 304 stainless steel during friction stir welding. 2003, Scripta Materialia, pp.1175-1180.

DOI: 10.1016/j.scriptamat.2003.08.022

[10] Sato, Y. S., Muraguchi, M. and Kokakawa, H. Microstructure and Proberties of Friction Stir Welded 304 stainless Steel Using W-Based Alloy Tool. in R. S. Mishra. Friction Stir Welding and Processing 4. 2007, pp.261-268.

DOI: 10.1002/9781118062302.ch15

[11] Guimarães P.R. and Mei. A.A., Precipitation of carbides and sigma phase in AISI type 446 stainless steel under working conditions. Journal of Materials Processing Technology. 2004, pp.1681-1689.

DOI: 10.1016/j.jmatprotec.2004.04.341