A study on backing block arrangement of dissimilar metal joining process of seamless ferritic and austenitic alloy by using an external tool
Introduction
In solid state welding process, friction welding is widely present and possesses a great popularity in producing defect free welding samples. Friction welding process is the metal joining process that gives high potential for industrial applications like power plants, automobiles, aerospace etc., Friction welding of Tube to Tube Plate is the new welding technique which was invented in the year 2006 and it was patented in the year 2008 [1]. The combine effect of rubbing on the surface of metals and the force given in axial direction, friction heat is generated to produce welding joints and there are two methods are followed by FWTPET process; one is clearance method and another method is interference. Generally, most of the easy practical approach is clearance method because the assemble of tube to tube plate is provided some small gap but in the case of interference there is no gap in between tube and tube plate and simultaneously in and around circumference of tube and tube plate is produced fine heat generation and strong bond is possible in interference method [2], [3], [4], [5], [6]. Several advantages of friction welding include the weldability of non-weldable alloys and produce quality welding samples [7], [8], [9], [10], [11], [12]. Friction welding of tube to tube plate using an external Tool (FWTPET) is capable for metal joining of both similar and dissimilar metals with high quality at required dimensions [13], [14], [15], [16], [17], [18], [19], [20]. Friction welding is eco-friendly to nature and more efficient and simultaneously ensure in joints to produce good mechanical and metallurgical properties. Backing block is employed to produce quality weld joints in dissimilar materials [21], [22], [23], [24]. In this article, it is compared with the condition without employing supporting block to map the difference of weldability. Taguchi L9 optimization technique is used to find the influencing input parameters and ANOVA is used to find the contribution of input process parameters that capable to produce high quality welding joint samples. Some research emphasized the application of Taguchi and ANOVA technique [25], [26], [27], [28], [29], [30].
Section snippets
Material selection and workpiece design
In this experimental Investigation, Seamless Ferritic and Austenitic Alloys which is shortly called as SA. SA 213 material is selected as tube and SA 387 is selected as tube plate. The welding is carried out with a tool made up of Tungsten Carbide whose configuration and dimensions are shown in Fig. 1 and the chemical composition is shown in Table 1. The tool diameter was 27 mm and 150 mm in length. At the beginning, the facing operation is made to make the surface level smooth and then turning
Optimization
Taguchi Method is provided for Signal-to-noise ratio to measure the quality and significant welding parameter. Here L9 Orthogonal Array is followed by Design of Experiments (DOE). There are three factors and three levels in L9 Orthogonal Array. The percentage of contribution is found by Analysis of Variance (ANOVA).
Three factors are considered such as speed, projection and depth of cut. The speed is about 730 rpm, 950 rpm and 1320 rpm, whereas projections are 0 mm, 1 mm and 2 mm and the depth
Results and discussions
The Experimental process is done with two conditions such as type 1 – Friction Welding with backing block and type 2 – friction welding without backing block. In both the conditions the Taguchi and ANOVA have to identify for most significant parameters and contribution of each process parameters. Regression equation is also used to analyze better joint strength.
Comparision of two conditions
The comparison statements are contained five different techniques which includes many special characterizations. First techniques are to compare the percentage of contribution for both types. Second technique is regression equation analysis. Third techniques is non-destructive test proof and fourth technique is destructive proof comparison and finally with microstructure and its grain size comparisons.
Special characterization
The special characterization contains various tests such as destructive tests, non-destructive test and microscopic test. Destructive test contains peel strength test and Impact test. Non- Destructive test contains Radiography test.
Conclusions
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FWTPET process is produced defect free samples with high quality welding joints. Here the study is about friction welding of SA 213 tube with SA 387 tube plate where is widely used in industrial application.
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Taguchi L9 is used to study about welding behavior at two different conditions one is welding with backing block and other one is without backing block at interference fit condition.
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The compressive strength of with and without backing block conditions are 3036.80 MPa and 2982.2 MPa
Acknowledgments
The authors like to convey our profound gratitude to the Department of Science and Technology, New Delhi, India and Financial support release under “Fast Track Young Scientist Scheme” through Science and Engineering Research Board (SERB/FTP/ETA/0282/2013) for this research project. The authors like to express our sincere thanks to Research & Development centre for providing us ambient laboratory facilities at RVS School of Engineering & Technology, Dindigul-624005, Tamil Nadu, India.
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