An experimental study on joining of AISI 304 SS to Cu by Nd-YAG laser welding process Bikash Ranjan Moharana a,⇑ , Sushant Kumar Sahu b , Anway Maiti a , Susanta Kumar Sahoo b , Tapas Kumar Moharana c a Department of Mechanical Engineering, C V Raman College of Engineering, Bhubaneswar, Odisha, India b Department of Mechanical Engineering, National Institute of Technology Rourkela, Odisha, India c National Council of Science Museums, Kolkata 700091, West Bengal, India article info Article history: Received 24 December 2019 Received in revised form 25 February 2020 Accepted 28 February 2020 Available online xxxx Keywords: Nd-YAG laser Dissimilar metal Copper micro-channels HAZ PMZ abstract In this current study, a challenging dissimilar metal combination AISI 304 stainless steel and copper is welded by pulsed wave Nd-YAG laser welding process without use of any filler material, followed by its mechanical as well as metallurgical investigation. Macroscopic as well as microscopic examination of the weld surface and weld bead has been carried out to observe the weld penetration depth and met- allurgical behavior inside the weld zone. Weld pool geometry confirms about attainment of full penetra- tion depth in pulsed wave Nd-YAG laser and also describes that the penetration depth is directly proportional pulse energy as (penetration depth 7J = 69%) < (penetration depth 14 J = 82%) < (penetration depth 21 J = 100%). The formed copper micro-channels suggest that the copper solidifies last and flows inside the weld zone matrix during the solidification. The average width of the heat affected zone (HAZ) and partially melting zone (PMZ) have been found to be 23.0 mm and 6.0 mm on the stainless steel (SS) side respectively. The microhardness (MH) study shows that (MH Copper = 75 HV0.1) < (MH Weld zone = 90–200 HV0.1) < (MH SS = 210 HV0.1). Ó 2020 Elsevier Ltd. All rights reserved. Selection and Peer-review under responsibility of the scientific committee of the 2nd International Conference on Processing and Characterization of Materials. 1. Introduction Metals are utilized as the most common materials in our every- day life from the ancient time to this modern era of technology. When these metals are used to manufacture a specific product, we require different joining processes to fix its different compo- nents. Majority of applications in a range of industries i.e. automo- tive, electronics, medical devices, power-generation etc. require welding of dissimilar materials. The functionality of dissimilar metal couples goes on increasing in process industries where the requirement cannot fulfil with single metal alone due to the limi- tation in properties. The stainless steel 304 and copper (ferrous and non-ferrous) dissimilar metal couple is extensively used in various industrial applications like nuclear power plants, food processing plants, steam turbine power plant, heavy electronics, switch gears etc., due to their complementary properties like high thermal and electrical conductivity of copper & corrosion resistance of SS 304. Pulsed Nd:YAG is an important laser welding process in terms of cost effectiveness, time-consuming, easy to handle, etc., Geusic et al. [1] first demonstrated it for a physical operation in 1964 at the Bell laboratory. The Nd: YAG laser welding technique is one of the most advanced processes in the field of welding for indus- trial applications. The absorptive capacity during Nd:YAG laser welding for reflective metals have greater coupling than CO 2 and chemical oxygen iodine laser (COIL) laser as described by Xie et al. [2]. The laser beam attenuation as well as the defocusing in plasma plume caused by the inverse Bremsstrahlung absorptions are negligible in Nd:YAG laser processing, as reported by Sab- baghzadeg et al. [3]. The solidification prospect in between two consecutive pulses for any high thermal conductivity metal or a low viscous molten metal such as copper aluminum etc., is very advantageous. Sanders et al. [4] described that the shorter wave- length in Nd:YAG laser is significantly better for weldability of alloys. This short pulse produced a stable weld pool by reducing the threshold irradiance. The high-energy absorption rate, low residual stress, and high welding speed give an advantageous weldability compared to CO 2 . The effect of pulse level on https://doi.org/10.1016/j.matpr.2020.02.953 2214-7853/Ó 2020 Elsevier Ltd. All rights reserved. Selection and Peer-review under responsibility of the scientific committee of the 2nd International Conference on Processing and Characterization of Materials. ⇑ Corresponding author. E-mail address: bikashrnjn@gmail.com (B.R. Moharana). Materials Today: Proceedings xxx (xxxx) xxx Contents lists available at ScienceDirect Materials Today: Proceedings journal homepage: www.elsevier.com/locate/matpr Please cite this article as: B. R. Moharana, S. K. Sahu, A. Maiti et al., An experimental study on joining of AISI 304 SS to Cu by Nd-YAG laser welding process, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2020.02.953