Investigation on Mechanical Properties of TIG Welded Joint and its Efficiency

Copyright © 2019 by author(s) and International Journal of Trend in Scientific Research and Development Journal. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0) (http://creativeco mmons.org/license s/by/4.0) ABSTRACT This work mainly pertains to improvement in the mechanical properties of IS 2062 steel plates welds through gas tungsten arc welding (GTAW) process. TIG (Tungsten inert gas) welding are well known welding techniques, that are being used in industries in the current age. Mild steel was the only commonly used material in TIG welding. Mild steel is the first material consumption. The comparison is done on the basis of the mechanical properties of the welded joint of TIG welding. This study is done on mechanical testing and non-destructive tests (DPT and radiography tests) of TIG welding on IS 2062 Mild steel plates.


INTRODUCTION
Welding is a fabrication process that materials, usually metals or thermoplastics, by causing fusion. In addition to melting the base metal, a filler material is typically added to the joint to form a pool of molten material (weld pool) that cools to form a joint that is usually stronger than the base material. Pressure may also be used in conjunction with heat, or by itself, to produce a weld. The factors affecting the welded joint strength is mainly based on type of joint, joint strength, no of joints to the joined, moisture presented in air and atmospheric conditions. The mild steel joining process is easy when compared to other conventional metallic materials and mild steel is advantageous material and its coefficient of expansion is finite. [1].

LITERATURE REVIEW 2.1 Tungsten Insert Gas (TIG) Welding:
In TIG welding method, the arc is strucked between small gap of non-consumption in tungsten electrode and the work piece in a shield of inert gases (Argon, Helium). Figure 1, represents the TIG welding processes.
Filler material is applied for matching the similar work pieces. Generally, DC arc is used with tungsten as the negative pole (DCEN). The excessive heat is generated at the tungsten electrode if this is used as anode.

Ahmetdurgutlu et.al [2]
Investigation the effect of hydrogen in argon as shielding gas for TIG welding of 316L austenitic stainless steel. They used current 115A welding speed 100 mm/min and gas flow rate 10 1/min for welding of 4mm thick plate. For all shielding media, hardness of weld metal is lower than that of HAZ and base metal. Penetration depth, weld bead width and mean grain size in the weld metal increase with increasing hydrogen content, The highest tensile strength was obtained for the sample welded under shielding gas of 1.5%H-Ar.

Ahmed Khalid Hussain et.al [3]
Investigating the effect of welding speed on tensile strength of the welded joint by TIG welding process of mild steel of 4mm thickness. The strength of the welded joint was tested by a universal tensile testing machine. Welding was done on specimen of single V butt joint with welding speed of 1800-7200 mm/mi. From the experimental results it was revealed that strength of the weld zone is less than base metal tensile strength increases with reduction of welding speed.

MATERIALS AND METHODOLOGY
The extended form of IS 2062 mild steel is consider for the present work. It was the thickness of 6mm and width of 20mm. The physical and mechanical properties of IS 2062 is represented in table 1.

RESULTS AND DISCUSSION
In this investigation leeb hardness testing has been done on leeb hard ness test machine is shown in figure 3.   One of the radiography tested welded zone sample is represented in table 5 and it is observed in figure5. 2. In the dye penetrant testing the defects found was incomplete fusion on the face side and lack of the penetration on the root side. On subjected the work piece of for leeb hardness test machine inspection was improper root and face penetration. Excess face penetration undercut and welded breed profile were encountered.
3. While using leeb hardness test the hardness of the metal is found at different positions i.e., at base metal, heat affected zone, weld pool at top middle and bottom positions. In the tensile test where the work piece is pulled from the sides to know the elongation to be 23%, yield load to be 103.950 KN. On performing the bend test the load corresponding value of the deflection on both the sides of the specimen were checked and found the maximum load for which the failure of the specimen will not occur is 12.5 KN.
4. After performing all these test on the work piece it can be concluded that the joint is good in the performance.