EVALUATION OF WELD BEAD CHARACTERISTICS OF AA6351

WELDED JOINTS USING GAS METAL ARC WELDING COLD METAL

TRANSFER (GMAW-CMT)

SUHAILA BINTI YACOB

A thesis submitted in partial

fulfillment of the requirements for the award of the

Degree of Master of Mechanical Engineering with honors.

Faculty of Mechanical and Manufacturing Engineering

SEPTEMBER 2014

ABSTRACT

Evaluation of weld characteristics of AA63 5 1 joints using GMAW -CMT

welding process was studied. The study is aimed to determine the effect of welding

speed, contact tip to work distance and material thickness on surface roughness,

waviness, weld bead width and weld bead height of AA6351 joints, identify type of

surface using visual inspection testing and an approach to determine crack defect

using dye penetration testing and eddy current testing. GMAW-CMT welding was

carried out on 5mm and 6mm thick AA6351 plates. An experimental test was

conducted at different level welding speed, contact tip to work distance and material

thickness. There are several equipment that had been utilized in order to execute the

work such as magnifying glass, vision measuring machine, MG-8 cam gauge, Insize

weld gauge, Mahr Marsuft XR 20 surface roughness machine, S-72 cleaner

remover,222 dye penetrant, LD-3 developer, NortecB 500 series portable eddy

current flaw detector and surface p~obe. The visual inspection, weld bead

measurement, surface roughness and waviness measurement, dye penetration testing

and eddy current testing have been performed to assess the weld characteristic of

AA6351 joints. The results of weld bead width, weld bead height, surface roughness

and waviness were analyzed using Minitab 16 software. The results indicated that

welding speed, contact tip to work distance and material thickness significantly

affected the weld bead width, weld bead height, surface roughness and waviness. The

lowest size weld bead width achieved was 5.5mm meanwhile the lowest size weld

bead height was 1.3mm.The average roughness; Ra values from 1.971 pm to

5.9394pm were attained on the AA6351 welded joint as well as an acceptable

surface finish. The inspection of AA6351 joints indicated the defects like light

spatter and porosity. Thus, it shows that GMAW-CMT welding process is the best

welding technique that can be applied for production.

ABSTRAK

Ciri-ciri sambungan kimpalan AA63 5 1 yang menggunakan proses kimpalan

GMAW - CMT telah dinilai.Tujuan kajian ini ialah menentukan kesan akibat

kelajuan kimpalanjarak tip dan ketebalan bahan terhadap kekasaran permukaan, .

keber~mbakan~lebar kimplan manik dan ketinggian kimpalan manik AA63 5 1 ,serta

mengenal pasti jenis kecacatan dengan menggunakan ujian visual dan kehadiran

retak pula ditentukan dengan mengunakan ujian penembusan pewarna dan ujian m s

pusar. Kimpalan GMAW - CMT telah dijalankan ke atas kepingan AA6351 yang

berketebalan 5mm dan 6mm.Ujikaji yang dijalankan mempunyai kelajuan kimpalan,

tip hubungan untuk bekerja jarak dan ketebalan bahan yang berbeza.Terdapat

beberapa peralatan yang telah digunakan untuk menjalankan projek seperti kaca

pembesar , mesin mengukur penglihatan,tolok MG -8 cam , tolok insize, mesin

permukaan kekasaran Marsufi XR 20, pencuci S -72 , pewarna penusukan 222,

pemaju LD -3, mudah alih pengesan arus pusar Nortec 0 siri 500 dan alat ,'

siasabn.Ujian visual, pengukuran kimpalan manik ,pegukuran kekasaran perrnukaan

dan pengukuran keberombakan , ujian penembusan pewarna dan ujian arus pusar

telah dijalankan untuk menilai ciri sambungan AA6351.Perisian MINITAB 16 telah

digunakan bagi menganalisi lebar kimpalan man&,ketinggian kimpalan

manik,kekasaran permukaan dan keberombakan.Keputusan menunjukkan bahawa

kelajuan kimpalanjarak tip dan ketebalan bahan telah memberi kesan kepada lebar

kimpalan manik , ketinggian manik kimpal , kekasaran permukaan dan

keberombakan . Saiz paling rendah kimpalan manik lebar dicapai adalah 5.5mm

Sementara itu saiz paling rendah ketinggian kirnpalan manik adalah 1.3mm.

Kekasaran purata; nilai Ra dari 1.971pm ke 5.9394ym telah dicapai pada AA6351

dikimpal bersama serta kemasan permukaan diterima Pemeriksaan sendi AA6351

menunjukkan kecacatan seperti merenjis cahaya dan keliangan.Oleh itu, ia

menunjukkan bahawa proses kimpalan GMAW - CMT adalah teknik kimpalan yang

terbaik yang boleh digunakan untuk pengeluaran.

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