scholarly journals A Combination of Keyhole GTAW with a Trapezoidal Interlayer: A New Insight into Armour Steel Welding

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3571 ◽  
Author(s):  
Zhenyu Fei ◽  
Zengxi Pan ◽  
Dominic Cuiuri ◽  
Huijun Li ◽  
Azdiar A. Gazder
Keyword(s):  
Chemical Composition ◽  
Weld Metal ◽  
Base Metal ◽  
Welding Process ◽  
Charpy Impact ◽  
Filler Materials ◽  
Temperature Phase ◽  
Ballistic Performance ◽  
Two Phase ◽  
Armour Steel

The ballistic performance of armour steel welds using austenitic filler materials is poor on account of the disparity in the mechanical properties of the weld and base metals. Consequently, a novel Keyhole Gas Tungsten Arc Welding process with a trapezoidal AISI309 austenitic stainless steel interlayer was developed to tailor chemical composition and microstructure by controlling the solidification sequence. Results show that the dilution rate in the weld metal region can reach up to 43.5% by placing a specially designed interlayer in between the base metal, providing a major scope for microstructure modification. Detailed weld analysis was undertaken by X-ray diffraction, optical and secondary and transmission electron microscopy, energy dispersive spectroscopy and electron back-scattering diffraction. The results from Vickers hardness indents and Charpy impact toughness testing at −40 °C show that the properties of the weld metal region are comparable to that of the base metal. This is ascribed to the weld metal comprising a two phase microstructure of martensite and retained austenite, which contribute to improvements in strength and toughness, respectively. Furthermore, the tailored chemical composition, microstructure and low temperature phase transformation in the weld metal may reduce the tendency toward both solidification cracking and hydrogen assisted cold cracking.

Characterization of Local Deformation in Welded Joints Using a Combined Experimental and Numerical Approach

2014 ◽  
Vol 627 ◽  
pp. 241-244 ◽  
Author(s):  
Pawel Kucharczyk ◽  
Sebastian Münstermann
Keyword(s):  
Chemical Composition ◽  
Weld Metal ◽  
Welded Joints ◽  
Base Material ◽  
Welding Process ◽  
Numerical Approach ◽  
Geometrical Model ◽  
Local Deformation ◽  
Heat Treated ◽  
Welded Structure

The microstructure of welded joints differs significantly from that of the base material, what changes their mechanical properties and influences fatigue life. The aim of this work was the investigation of the local deformation field within a butt joint made of 10 mm thick structural steel S355. However, a direct sampling even of the weld metal was impossible due to small dimensions of butt joints. Therefore, the following procedure was utilized in order to manufacture big samples of the microstructure identical to that of the local weldment areas.A geometrical model of the welded structure describing the relevant areas e.g. weld metal, heat-affected zone was established. It was based on the results of the metallographic investigations, hardness mapping and electron-probe-micro-analysis of the local chemical composition. The welding process was numerically simulated using SYSWELD program to estimate the time-temperature-transition (TTT) curves for each identified area. The parameters of the heat input source were calibrated. Afterwards, the material of the defined chemical composition was heat-treated according to the TTT curves. For the validation purpose the heat-treated work pieces were evaluated in terms of microstructure and hardness distribution. Finally, the up-scaled samples of the respective bulk microstructure were manufactured and investigated in monotonic tests.

Application of FIB/SEM/EBSD for Evaluation of Residual Strains and Their Relationship to Weld Metal Hydrogen Assisted Cold Cracking

2012 ◽  
Author(s):  
W. L. Costin ◽  
I. H. Brown ◽  
L. Green ◽  
R. Ghomashchi
Keyword(s):  
Residual Stresses ◽  
Weld Metal ◽  
Base Metal ◽  
Heat Affected Zone ◽  
Ion Beam ◽  
Base Material ◽  
Welding Process ◽  
Cold Cracking ◽  
Predictive Methods ◽  
Residual Strains

Hydrogen assisted cold cracking (HACC) is a welding defect which may occur in the heat affected zone (HAZ) of the base metal or in the weld metal (WM). Initially the appearance of HACC was associated more closely with the HAZ of the base metal. However, recent developments in advanced steel processing have considerably improved the base material quality, thereby causing a shift of HACC to the WM itself. This represents a very serious problem for industry, because most of the predictive methods are intended for prevention of HACC in the HAZ of the base metal, not in the weld metal [1]. HACC in welded components is affected by three main interrelated factors, i.e. a microstructure, hydrogen concentration and stress level [2–4]. In general, residual stresses resulting from the welding process are unavoidable and their presence significantly influences the susceptibility of weld microstructures to cracking, particularly if hydrogen is introduced during welding [5]. Therefore various weldability tests have been developed over the years which are specifically designed to promote HACC by generating critical stress levels in the weld metal region due to special restraint conditions [4, 6–8]. These tests were used to develop predictive methods based on empirical criteria in order to estimate the cracking susceptibility of both the heat-affected zone and weld metal [4]. However, although the relationship between residual stress, hydrogen and HACC has received considerable attention, the interaction of residual stresses and microstructure in particular at microscopic scales is still not well understood [5, 9–21]. Therefore the current paper focuses on the development and assessment of techniques using Focused Ion Beam (FIB), Scanning Electron Microscopy (SEM) and Electron Backscatter Diffraction for the determination of local residual strains at (sub) micron scales in E8010 weld metal, used for the root pass of X70 pipeline girth welds, and their relationship to the WM microstructure. The measurement of these strains could be used to evaluate the pre-existing stress magnitudes at certain microstructural features [22].

Effects of Filler Compositions on Mechanical and Physical Properties of the Dissimilar Resistance Spot Welded between Aluminium Alloy and Carbon Steel

2015 ◽  
Vol 656-657 ◽  
pp. 422-427
Author(s):  
Yustiasih Purwaningrum ◽  
Triyono ◽  
Muhammad Fathan
Keyword(s):  
Carbon Steel ◽  
Weld Metal ◽  
Physical Properties ◽  
Aluminium Alloy ◽  
Base Metal ◽  
Testing Machine ◽  
Optical Microscope ◽  
Filler Materials ◽  
Al Alloy ◽  
Resistance Spot

The resistance spot weld (RSW) of dissimilar materials betweeen steel and aluminium is generally more complex than that of similar materials due to the extreme differences in the mechanical, physical and chemical properties of the base metals. This study proposed the use of filler material to connect the differences of their properties. Al-Alloy 5083 with thickness of 4 mm and 1.2 mm thick carbon steel SS400 were joined in lap joint types using RSW with the filler materials. The filler materials were a mixture of steel and aluminium in which weight composition variations (Fe:Al) were 90:10; 70:30; 30:70 and 90:10 in percent. The physical properties were examined based on the microstructure using optical microscope while the mechanical properties were measured with respect to the strength and hardness using Universal Testing Machine and Vickers Microhardness respectively. Results showed that weld metals with filler composition of 70:30% had highest shear-strength. The microstructure examinations showed that Microstructure of base metal and HAZ carbon steel was ferrite and perlite while that of weld metal was bainite. There were no significant differences in the microstructures and the hardness of weld metal, HAZ, and the base metal of aluminium alloy-5083 due to nonheat-treatable material.

scholarly journals PENGARUH MEDIA PENDINGINAN TERHADAP KEKERASAN DAN STRUKTUR MIKRO HASIL PENGELASAN OXY ACETYLENE PADA MATERIAL BAJA ST-37

2017 ◽  
Vol 5 (2) ◽  
Author(s):  
Made Angga Priadi ◽  
I Nyoman Pasek Nugraha ◽  
Gede Widayana
Keyword(s):  
Weld Metal ◽  
Base Metal ◽  
Heat Affected Zone ◽  
Quantitative Research ◽  
Welding Process ◽  
Air Cooling ◽  
Water Cooling ◽  
Independent Variable ◽  
The Mean ◽  
Cooling Media

Media pendingin merupakan suatu substansi yang berfungsi dalam menentukan kecepatan pendinginan yang dilakukan terhadap material yang telah diuji dalam perlakuan panas. Penelitian ini bertujuan untuk mengetahui tingkat kekerasan dan pengamatan struktur mikro material baja ST-37 yang dipengaruhi media pendinginan air, udara dan oli serta penelitian ini dapat memberikan bahan referensi bagi lingkup pendidikan teknik mesin dan sebagai acuan di dunia industri dalam menggunakan media pendingin pada proses pengelasan. Adapun jenis metode yang digunakan dalam penelitian ini adalah metode penelitian eksperimen. Terdapat dua jenis variable yang digunakan dalam penelitian ini yaitu variabel bebas yang berupa media pendingin air, media pendingin udara dan media pendingin oli dan variabel terikatnya berupa sifat kekerasan. Dari hasil penelitian yang telah dilakukan dimana kekerasan daerah logam induk dengan media pendingin air memperoleh nilai rata-rata sebesar 63,10 Kg/mm2, pendingin udara memperoleh nilai rata-rata sebesar 65,61 Kg/mm2, dan media pendingin oli memperoleh nilai rata-rata sebesar 62,68 Kg/mm2. Kekerasan pada daerah HAZ dengan media pendingin air memperoleh nila rata-rata sebesar 68,49 Kg/mm2, media pendingin udara memperoleh nilai rata-rata sebesar 71,05 Kg/mm2 dan media pendingin oli memperoleh nilai rata-rata sebesar 70,34 Kg/mm2. Kekerasan pada daerah logam las dengan media pendingin air memperoleh nilai rata-rata sebesar 60,99 Kg/mm2, media pendingin udara memperoleh nilai rata-rata sebesar 61,79 Kg/mm2 dan media pendingin oli memperoleh nilai rata-rata sebesar 60,79 Kg/mm2. Berdasarkan dari hasil yang telah didapatkan baik pada logam induk, daerah HAZ dan logam Las dimana tingkat kekerasan yang lebih baik diperoleh dari proses pendinginan udara dibandingkan dengan media pendingin air dan media pendingin oli dari proses pengelasan oxy acytelene.Kata Kunci : Baja ST-37, Kekerasan Material, media pendinginan. The cooling media is a substance which has a function to determine the speed refrigeneration which carried out of the material that has been tasted by heat treatment. The objective of the research is to know the level of hardness and the observation of steel ST-37 material which is affected by cooling media such as water, air, and oil. Also this research may give a reference for Engineering Department of Education and industry in using cooling media for welding process. There is a method that use in this research, that is called quantitative research. There are two variables that use in this research. Independent variable and dependent variable. An independent variable are water, air, and oil cooling media. On the other hand, a dependent variable is nature of hardness. In this research the researcher got a results where the mean of hardness of the base metal area with the water cooling media is 63.10 Kg/mm2, in air conditioning is 61Kg/mm2, and the oil cooling is 62.68 Kg/mm2. The mean of a hardness in Heat Affected Zone (HAZ) by water cooling media 68,49 Kg/mm2, air cooling media is 71,05 Kg/mm2 and an air cooling is 70,34 Kg/mm2. The mean of Hardness in the weld metal area with water cooling media is 60,99 Kg/mm2, air-cooling media is 61,79 Kg/mm2 and oil-cooling media is 60,79Kg/mm2. Based on the result which has been gotten from base metal, Heat Affected Zone (HAZ), and weld metal where the best hardness level is obtained from air-cooling process rather than water cooling media and oil cooling media from oxy acytelene welding process.keyword : Cooling media, steel ST-37, hardness properties.

Characterization of the Microstructure and Toughness of DSAW and ERW Seam Welds of Older Linepipe Steels

2002 ◽  
Author(s):  
J. A. Gianetto ◽  
D. K. Mak ◽  
R. Bouchard ◽  
S. Xu ◽  
W. R. Tyson
Keyword(s):  
Weld Metal ◽  
Base Metal ◽  
Heat Affected Zone ◽  
Electrical Resistance ◽  
Crack Tip ◽  
Charpy Impact ◽  
Initiation Toughness ◽  
J Integral ◽  
Crack Tip Opening Displacement ◽  
Linepipe Steel

The aim of the present work is to quantify the seam weld properties, including both weld metal and heat affected zone regions, for a series of double-submerged-arc welded pipe, and the base metal and bondline regions for an electrical resistance welded linepipe steel. The chemical composition, microstructure, microhardness, tensile properties, Charpy impact toughness and J-integral/crack-tip opening displacement fracture resistance were characterized for linepipe produced between 1953 and 1981. The toughness results of the base metal, heat affected zone and weld metal regions of the older (higher carbon) linepipes were significantly poorer than those obtained for a more modern low-C microalloyed linepipe steel. In the latter case the base metal, HAZ and weld metal regions failed by ductile fracture at room temperature in both fracture toughness (quasi-static) and Charpy impact tests. It was possible to show that there is a linear correlation between the J-integral at 0.2 mm crack growth and the upper shelf Charpy energy. It is, however, important to note that the Charpy transition temperatures of the older pipes are considerably higher than for the modern pipe. In the case of the electrical resistance weld, very poor toughness was observed for the bondline. Fracture occurred along the bondline in a brittle mode (cleavage) that was attributed to the formation of a coarse, relatively hard microstructure and the presence of inclusions along the bondline region. In addition, it was shown using base-metal BxB and Bx2B samples that initiation toughness is a function of the remaining uncracked ligament. This emphasizes the necessity of ensuring that the crack-tip constraint in the test specimens is similar to the constraint in the crack geometry being assessed.

The Effect of Double Pass GMAW Process on Microstructure and Mechanical Properties of Aa 6061-T6 Joining Plates

2012 ◽  
Vol 510-511 ◽  
pp. 98-104 ◽  
Author(s):  
S.R.S. Bakar ◽  
M.Y. Ahmad ◽  
Muhammad Faizol Ahmad Ibrahim ◽  
A. Jalar ◽  
S.J.S. Djalil ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Weld Metal ◽  
Base Metal ◽  
Gas Metal Arc Welding ◽  
Welding Process ◽  
Double Pass ◽  
Metal Solidification ◽  
Microstructure And Mechanical Properties ◽  
First Pass ◽  
Welding Technique

This paper presents an investigation on microstructure and mechanical properties of welded AA 6061-T6 plate using filler metal ER 4043 in the Gas Metal Arc Welding (GMAW) process. Double pass welding technique on both sides of 5 mm thick plate or more is required to provide sufficient weld pool in the joint. The weld metal of the first welding pass exhibits finer microstructure than the second welding pass. The size of Mg2Si precipitations in the heat-affected zone (HAZ) region is larger than in the base metal due to the welding process that reheats the alloy from the T6 condition above the eutectic temperature. Rapid cooling of the first pass and moderate cooling rate for the second pass during weld metal solidification eventually resulted in significantly change the shape and size in the microstructure that had affected the hardness and mechanical properties. Comparisons made to the base metal on the hardness test results found that the hardness of first pass weld metal dropped by 15%, and by 37.5% for the second weld metal, while the hardness at the boundaries of the first and second weld metals dropped by 32.5%. The ultimate tensile strength and strain of the weld joint with ER 4043 also decreased by 48% and 94% respectively. Based on the findings of the study, it is concluded that even though the double sided welding technique is able to overcome shallow weld penetration to avoid stress concentration that leads to the fatigue failure, the metallurgical changes eventually contributes to degradation of mechanical properties.

scholarly journals Twin-Wire Pulsed Tandem Gas Metal Arc Welding of API X80 Steel Linepipe

2018 ◽  
Vol 2018 ◽  
pp. 1-11
Author(s):  
Wenhao Wu ◽  
Ming Zhao ◽  
Haiyan Wang ◽  
Yanxia Zhang ◽  
Tong Wu
Keyword(s):  
Corrosion Resistance ◽  
Weld Metal ◽  
Base Metal ◽  
Corrosion Behavior ◽  
Arc Welding ◽  
Production Efficiency ◽  
Gas Metal Arc Welding ◽  
Welding Process ◽  
Metal Arc Welding ◽  
X80 Steel

Twin-Wire Pulsed Tandem Gas Metal Arc Welding process with high welding production efficiency was used to join the girth weld seam of API X80 steel linepipe of 18.4 mm wall thickness and 1422 mm diameter. The macrostructure, microstructure, hardness, and electrochemical corrosion behavior of welded joints were studied. Effects of temperature and Cl− concentration on the corrosion behavior of base metal and weld metal were investigated. Results show that the welded joint has good morphology, mechanical properties, and corrosion resistance. The corrosion resistance of both the base metal and the weld metal decreases with increasing temperature or Cl− concentration. In the solution with high Cl− concentration, the base metal and weld metal are more susceptible to pitting. The corrosion resistance of the weld metal is slightly lower than that of the base metal.

Hot corrosion performance of bare and pulsed current welded Fe-based A-286 alloy in chlorine and sulphur environment

2021 ◽  
pp. 095440892110434
Author(s):  
S M Muthu ◽  
R Dinek ◽  
P Mohan ◽  
K Jithesh ◽  
M Arivarasu
Keyword(s):  
Weld Metal ◽  
Base Metal ◽  
Hot Corrosion ◽  
Research Work ◽  
Welding Process ◽  
Mapping Technique ◽  
Porous Iron ◽  
Pulsed Current ◽  
Bare Metal ◽  
Corrosion Performance

This present research work focuses on the hot corrosion performance of the base metal, weldment, and weld metal of A-286 alloy in sodium sulphate (Na2SO4)–5% sodium chloride (NaCl)–7.5% sodium metavanadate (NaVO3) (3SM) atmosphere at 700 °C. A pulsed current gas tungsten arc welding process is employed to make a similar joining of A-286 alloy using the filler material ERNiCrMo-3. The corrosion kinetics of the specimens has been determined using the thermo-gravimetric technique. The phase compositions of the reaction products are studied by X-ray diffraction, and the surface morphology of the scales is explored by scanning electron microscope analysis. The corroded samples are subjected to a cross-sectional study to ensure the corrosion attack and scales thickness using a SEM with elemental mapping technique. The result indicates that weldment showed better corrosion resistance than bare metal. A thick oxide scale could be found in the bare metal specimen than the weld metal. In the case of base metal, the formation of non-adherent and porous iron (III) oxide (Fe2O3) leads to rapid corrosion. The weight gain of weldment is about 1.96 and 1.13 times less than bare alloy and weld metal.

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