In the case of welded joints there are defects that can not be seen with the naked eye.

These defects being within the material to know if they can cause failures in the future, should be

investigated and ranked in an acceptance class according to certain standards in the field. In this

paper we investigate using the ultrasonic control method, the welding seam between two butt

welded sheets

Andrei DIMITRESCU

Claudiu BABIS

Elisabeta BANICA

Loredana DASCALU

Oana CHIVU

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Fiabilitate si Durabilitate - Fiability & Durability   No 2/ 2018  Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X   19 THE INVESTIGATION OF A BUTT WELD WITH ULTRASOUND  PhD. Claudiu BABIS,Faculty of Engineering and Management of Technological Systems „Politehnica ” University, claudiubbs@gmail.com PhD. Oana CHIVU, Faculty of Engineering and Management of Technological Systems „Politehnica ” University, virlan_oana@yahoo.co.uk PhD. Andrei DIMITRESCU, Faculty of Engineering and Management of Technological Systems „Politehnica ” University, andrei_dimitrescu@yahoo.com PhD. Loredana DASCALU, Faculty of Engineering and Management of Technological Systems „Politehnica ” University, Dascalu_loredana_cristina@yahoo.com PhD. Elisabeta BANICA, Theory of Mechanisms and Robots Department „Politehnica ” University, Bucuresti, Romania, banicaelisabeta29@yahoo.com  Abstract: In the case of welded joints there are defects that can not be seen with the naked eye. These defects being within the material to know if they can cause failures in the future, should be investigated and ranked in an acceptance class according to certain standards in the field. In this paper we investigate using the ultrasonic control method, the welding seam between two butt welded  sheets.  Keywords: Investigation method, ultrasound, butt welded joint   1.INTRODUCTION   The ultrasonic control method is a non-destructive defectoscopic method.  The defectoscopy is a set of physical tests that show defects from the material phase, the semi-finished product, after the machining, to the finished part phase, reaching to the assembly and subassemblies phase or even in the operational phase.  Ultrasounds are mechanical vibrations with frequencies between 16 kHz and 10 14 Hz.  Through the ultrasonic control method, all categories of metallic and non-metallic materials can be controlled.  By this method, it is possible to reveal all categories of defects, especially interior ones.  The ultrasonic control method is useful because it highlights internal discontinuities that can cause serious damage [1-2]. The ultrasonic investigation is also applied after the reconditioning of the parts, in order to detect any discontinuities that could be added further after reconditioning [3-5].  2. EXPERIMENTAL RESEARCH   In the paper is presented an ultrasonic investigation of the butt welded  joint  which is shown in Figure 1.  The material from which those two sheets are made is a general purpose steel, with the symbol S 235 JR, according to EN 10028-2, whose chemical composition is shown in Table 1.  The mechanical characteristics of the material from which the welded piece is made are shown in Table 2. Fiabilitate si Durabilitate - Fiability & Durability   No 2/ 2018  Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X   20  Figure 1 The welded sample subjected to ultrasonic control 1-welding seam; 2 and 3-butt welded sheets Table  1. Chemical composition of the base material Base material Chemical composition % C Mn P S Si Other elements S235 JR 0,18 0,80 0,050 0,050 - - Table 2 Mechanical characteristics of the base material Base material Mechanical characteristics Rm (MPa) Rp0,2, (MPa) A, (%) KCUmin, (J/cm2) T (0C) KVmin, (J) S 235 JR 360-440 240 23 - - 27 + 20 0C   The ultrasonic investigation of the butt welded sheets was made with the USM 35 X defectoscope, shown in Figure 2 [6]. Fiabilitate si Durabilitate - Fiability & Durability   No 2/ 2018  Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X   21  This defectoscope is designed to investigate the discontinuities of various industrial parts. The device is portable and can be used in the laboratory as well as in the field.  The use of the defectoscope is only made by qualified personnel. The defectoscope is complex, it includes in its construction several elements that must be known by the operator. From the description of the defectoscope, from the general view we can list the following elements:  1-on / off key 2-key to select function groups 3-key to select the operating level 4-key to record data 5-key for data transfer 6-key for enhanced playback of the signal area 7-key for oscillogram capture 8-button rotary to adjust the amplitude of the signals 9-key for setting the amplitude variation step 10-area network and data transfer jacks 11-connectors for connecting the sensors 12-warning lights 13-key to select functions 14-button rotator for assigning function values 15-area dialog or data display  The program used by the device is designed on three levels of operation. Each operating level has five function groups, each group containing four functions. Operating levels are marked with digits 1; 2 and 3, shown after the first function group.  The selection of the operating levels is done by pressing successively key 3.  Selecting a specific group of functions within an operating level is done by pressing one of the keys 2.  Selecting a function within a function group is done by pressing one of the keys 13.   Figure 2 Ultrasonic Defectoscope USM 35 X Fiabilitate si Durabilitate - Fiability & Durability   No 2/ 2018  Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X   22 In the first phase, the ultrasonic control is started using the longitudinal wave probe.  The piece control begins with the calibration of the defectoscope with the block  of calibration A1, as shown in Figure 3.   After the calibration, the  ultrasound control is done on the right side of the piece, along the longitudinal wave examining area, using the MB 4S probe, as shown in Figure 4.  Then we will go to the left side ultrasound control, along the longitudinal wave scan area, using the MB 4S probe, similar to the left-hand control, as shown in Figure 5.  In the second phase, the ultrasonic control is performed using a MWB 45-2 (2 MHz) inclined touch probe.  The second phase starts this time with calibration with the transversal touch probe, as seen in Figure 6.  Then, follow the control itself with the inclined touch probe, as can be  seen in Figure 7.    Figure 3 Calibrating the defectoscope with block A1  Fiabilitate si Durabilitate - Fiability & Durability   No 2/ 2018  Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X   23  Figure 4 Ultrasonic examination with longitudinal waves on the left side of the joint      Figure 5 Ultrasonic examination with longitudinal waves on the right side of the joint   Fiabilitate si Durabilitate - Fiability & Durability   No 2/ 2018  Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X   24  Figure 6 Calibrating the inclined transducer waveguide defectoscope    Figure 7 Controlling the specimen itself using an inclined transducer waveguide defectoscope  3. EXPERIMENTAL RESULTS  Fiabilitate si Durabilitate - Fiability & Durability   No 2/ 2018  Editura “Academica Brâncuşi” , Târgu Jiu, ISSN 1844 – 640X   25  Figure 8 Detection of the discontinuity    As can be seen in Figure 8, we are dealing with a crack discontinuity.  4. CONCLUSIONS   The defect is a 49.4 mm long crack at a depth of 9.41 mm.  This defect has to be removed by air arc gouging, but this is the subject of another paper.    REFERENCES  [1] Monika O., Peter P.,Milan U.,Fracture mechanism differences created by fatigue and impact test,  Materialstoday Proceedings, vol. 4/issue 3, pp 5921-5924, 2017 [2] Zhao-Ling W, Heng X,Direct modeling of multi-axial fatigue failure for metals,  International Journal of Solids and Structures,  pp 216-231, 2017 [3] Amza G., Babis C., Nitoi D., The influence of the specific rehabilitation techniques "toe grindig" and "wig remelting" in case of welded structure, Metalurgija, vol 53, pp 71-74, 2014 [4] Amza, G., Nitoi D., Babis C., Amza C., Apostolescu Z., Influence of the Milling Weld Toe and WIG Remelting Reconditioning Technology to Welded Pieces in the Case of Fatigue Testing, Advanced Materials Research, vol 684, pp 362-366, 2013 [5] Armando L., Rama I., José A., Carlos A., Branco G., Fatigue behaviour of T welded joints rehabilitated by tungsten inert gas and plasma dressin, Materials and Design, vol 32, pp 4705-4713, 2011 [6] Mihai A., Voicu M., Rujinski Dumitrache Al., Mateiasi G., Funar St., Dumitrascu C., Inspectia calitatii-Metode nedistructive de examinare, Editura Printech, 2011 

THE INVESTIGATION OF A BUTT WELD WITH ULTRASOUND

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THE INVESTIGATION OF A BUTT WELD WITH ULTRASOUND

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