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MECHANICAL STRENGTH OF THE WELD METAL IN CK45 CARBON STEEL H. R. Ghazvinloo1,2 and A. Honarbakhsh-Raouf1 The procedure of gas-metal arc welding (GMAW) has received much attention in recent years and has numerous beneficial applications in the industry. The arc voltage, welding current and welding speed are three independent variables of this process that may affect the mechanical properties of the weld metal. As one of the most important mechanical properties of the weld metal, we can mention its yield strength and ultimate tensile strength. Therefore, we focus on the strength of the weld metal in CK45 carbon steel welded by the robotic GMAW process under different conditions. The accumulated results clearly illustrate that the strength of the weld metal is a monotonic function of the variables of welding. Keywords: Gas-metal arc welding, welding variables, strength, weld metal.

Welding process plays an important role in the manufacturing industries. There are more than 100 processes within the technology of welding [1]. The gas-metal arc welding (GMAW) is a fusion-welding process with extensive applications in the industry [2]. In this process a continuous wire electrode and a shielding gas are delivered through the nozzle of a welding gun [3]. An electric arc is generated between the wire electrode and the weld pool. Gases are used to shield the weld pool and flow through the nozzle of the welding torch. These gases are argon (Ar), helium (He), CO 2 , and their mixtures [4]. The GMAW process received wide applications in the industries due to its advantages, such as high reliability, all-position capability, low cost, high productivity, high deposition rate, ease of use, absence of fluxes, cleanliness, and ease of mechanization [2]. The robotic welding process has more advantages than the conventional manual process because the quality of the weld is more consistent, the process speed is higher as compared with the manual process. Moreover, we get less wastes and reduced costs [5]. The strength of the weld metal is one of the most important factors that should be taken into consideration when designing. The high strength of the weld metal ensures its acceptable resistance to failure under various loads. The arc voltage, welding current, and welding speed are important parameters of GMAW affecting the strength of the weld metal. As far as we know, relatively little information is available on the mechanical properties of the weld metal in medium-carbon steels. In the present research work, an attempt is made to study the effect of robotic GMAW parameters on the strength of the weld metal in CK45 carbon steel. Materials and Methods The CK45 medium-carbon steel (according to the DIN-1.1191 standard) in the form of a plate with a thickness of 20 mm was used as a base material and the ER70S-6 (AWS-A5.18 Classification) wire electrode with a diameter of 1 mm was used as a filling metal. 1 2

Department of Materials Engineering, Semnan University, Semnan, Iran. Corresponding author; e-mail: [email protected].

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