Investigating the Microstructural Properties and Phase Distributions of TIG Welded AISI/SAE 304L Stainless Steel Runners Used in TNT Filling of Ammunitions

Among the stainless steels, the most widely used group is austenitic stainless steels. The prominent reason why austenitic stainless steels are preferred in welded stainless steel fabrications is their good weldability. AISI/SAE 304L austenitic stainless steels exhibit adequate corrosion resistance in oxidizing environments. AISI/SAE 304L austenitic stainless steels are also used in filling interfaces of runners between the Tri-Nitro-Toluen filling vessel and ammunitions in defense industry. For the manufacture of the runners, the stainless steel plates and the stainless steel pipes are mainly joined by fusion welding. These runners are cleaned with hot tapping water at 70°C after each filling of ammunitions by TNT so that cleaning operation can deteriorate the corrosion properties of runners especially weld zones. Austenitic stainless steel weldments include basically delta-ferrite and austenite phases on weld regions. Delta ferrite phase exhibits resistance to chloride bearing medias while austenite phase is more resistive to high temperature oxidizing ambientsIn this study; 3 mm thick 304L austenitic stainless steel plates and rings are welded to each other with two different filler weld wires of ER316L and ER2209 by Tungsten Inert Gas welding method under pure argon shielding gas. Weld metals and heat-affected zones of welded joints were examined using optical metallurgical microscope. It has been determined that the additional filler weld wires have changed the weld metal and the heat affected zone microstructures and phase distributions dominantly. Microstructures of all welded joints have been compared. Besides, phase distributions of weld metals and heat effected zones are made by image analysis software and Schaefflers diagram. ER2209 welding filler metal increased the phase fraction of delta-ferrite in weld metals while it decreased the austenite phase fraction as compared to ER316L filler metal.

Keywords:

304L Stainless Steels TIG Welding, Phase Analysis,

PDF

___

Classification of Welding consumables ISO14343, 2017.
Classification of Welding consumables AWS A.5.9, 2017.
Gadewar S., Swaminadhan P., Harkare M., Experimental Investigations of Weld Characteristics for a Single Pass TIG Welding with Stainless Steel, Journal of Engineering and Technology, 2(8), pp. 3676-3686, 2010.
Gunn R.N., Duplex stainless steels microstructure properties and applications, Abington Publishing, p.58, 2003.
Gülenç B., Develi K., Kahraman N., Durgutlu A., Experimental Study of the Effect of Hydrogen in Argon as a Shielding Gas in MIG Welding of Austenitic Stainless Steel, International Journal of Hydrogen Energy, 30(13), pp. 1475–1481, 2005.
Joseph O.O., Leramo R.O., Ojudun O.S., Journal of Materials and Environmental Science 6-1, p. 101, 2015.
Lippold J.C., Kotecki D., Welding Metallurgy and Weldability of Stainless Steels, Wiley Interscience, pp. 56-57, 2005.
Margolin M., Skettini E., Ammunition Loading Techniques, Explosive Development Section Feltman Research and Engineering Laboratories, p. 2, 1958. Patel A., Patel S., The Effect of Activating Flux in Tig Welding, International Journal of Computational Engineering Research 4(1) pp. 65-70, 2014.
Pollard B., Welding brazing and soldering, ASM Metals Handbook, V.6, pp 482-493, 1993.
Properties and Selection; Non-Ferrous Alloys and Special Purpose Materials, ASM International, ASM Handbook Volume 2, pp. 618-627, 2005.
Standard Specification for Welding, Brazing, and Fusing Qualifications, ASME BPVC Section IX, 2019.
Standard Test Method for Determining Volume Fraction by Systematic Manual Point Count; ASM International: Almere, The Netherlands, ASTM E562-11, 2011.
Standard Practice for Determining the Inclusion or Second Phase Constituent Content of Metals by Automatic Image Analysis; ASM International: Almere, The Netherlands, ASTM E1245, 2008.
Standard Specification for Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip for Pressure Vessels and for General Applications, ASTM A240, 2017.
Talabi S.I., Owolabi O.B., Adebisi J.A., Yahaya T., Advanced Reservoir and Production Engineering Manual 9-4, p. 181, 2014.
Tülbentçi K., Paslanmaz Çeliklerin Kaynağı, Böhler Kaynak Dünyası, ss 5-10, 1985.
William D. Callister J. , Rethwisch D. G., Materials Science and Engineering: An Introduction, John Wiley & Sons Inc., pp 57-58, 2014.