The Standard, in catering for structures subject to fatigue conditions as well as statically loaded structures, provides two categories of welds with two differing levels of weld quality assurance associated with the different types of service to which the welds are subjected. The intention is that the designer select the category suited to the severity of the service and nominate this on the drawings. Where a structure contains both categories, this nomination of appropriate categories will ensure that appropriate levels of supervision and inspection will be applied to the relevant parts of the structure.
The Standard, in catering for structures subject to fatigue conditions as well as statically loaded structures, provides three categories of welds with three differing levels of weld quality assurance associated with the different types of service to which the welds are subjected. The intention is that the designer should select the category suited to the severity of the service and nominate this on the drawings. Where a structure contains more than one category, this nomination of appropriate categories will ensure that appropriate levels of supervision and inspection will be applied to the relevant parts of the structure.
This Joint Australian/New Zealand Standard was prepared by Joint Technical Committee WD-003, Welding of Structures. It was approved on behalf of the Council of Standards Australia on 3 June 2003 and on behalf of the Council of Standards New Zealand on 4 June 2003. It was published on 5 August 2003.
The primary function of shielding gas is to protect the arc and molten weld, pool from atmosphere oxygen and nitrogen. If not properly protected it forms oxides and nitrites and result in weld deficiencies such as porosity, slag inclusion and weld embrittlement. Thus the shielding gas and its flow rate have a substantial effect on the following: Arc characteristics, Mode of metal transfer, penetration and weld bead profile, speed of welding, cleaning of action, weld metal mechanical properties. Fig 4.7 shows variation of hardness of specimens with gas flow rate at 100 Amperes on weld pool and HAZ. On the weld pool the hardness is decreasing with increase in gas flow rate which was expected because at high gas flow rate the tendency of formation of oxides and nitrites is very less and generally oxides and nitrites are harder and brittle as compared to their parent metals. However, on HAZ surprisingly the maximum hardness is achieved at maximum gas flow rate. Increase in gas flow rate may lead to better protection against atmospheric contamination, yielding better quality weld. However, much increase in gas flow rate may cause turbulance causing enhanced chance of gas absorption from the surroundings and un-controlled protection of the arc and weld pool .
Austenitic is the most widely used type of stainless steel. It has a nickel content of at least of 7%, which makes the steel structure fully austenitic and gives it ductility, a large scale of service temperature, non-magnetic properties and good weld ability. The range of applications of austenitic stainless steel includes house wares, containers, industrial piping and vessels, architectural facades and constructional structures.
In DP steels, martensite is formed by carbon increasing the hardenability of the steel at practical cooling rates. Transitional metals such as Manganese, chromium, molybdenum, vanadium, and nickel also help increase hardenability either individually or in combination. Carbon also acts as ferrite solute strengthener for martensite. Mechanical properties and good resistance spot welding ability are as results from carbon that acts as ferrite solute strengthener for martensite. However, some adjustment is required to weld highest strength grade steel (DP 700/1000).
TIG welding also known as gas Tungsten Arc Welding (GTAW) uses a non consumable electrode and a split filler metal with an inert shielding gas. TIG process welding set utilizes suitable power sources, a cylinder of argon gas, a welding torch that was linked to electric cable for current supply, and tubing for shielding gas supply. The characteristic of the torch formed is, having a cap at the back end to protect the quite long tungsten electrode against unintended breakage. (Ahmed, 2010). Figure 3.2 shows the Model Miller TIG welding machine is used in this experiment.
This work aims at the analysis and optimization of joining similar grades of stainless steel by TIG welding. The parameters like current, filler materials, welding speed are the variables in the study. The mechanical properties and microstructure of 310 austenitic stainless steel welds are investigated, by using stainless steel filler material of different grades. Higher tensile strength was achieved with a current 120A and 309L filler rod and also the weld has fewer defects.
If steel have more than 0.021% carbon at steel producing temperatures then it converts into a face-centered cubic (FCC) builds, called austenite or γ-iron. It is also soft and metallic but can melt considerably more carbon, as much as 2.1% carbon at 1,148 °C, which reveals the upper carbon content of steel.[33,34] Martensite has a lower density than austenite does, so that conversion between them, findings in a change of volume. In this case, extension occurs. Internal stresses from this extension generally take the form of solidity on the crystals of martensite and tension on the remaining ferrite, with a correct amount of shear on both elements.
Austenitic is the most broadly utilized sort of hardened steel. It has a nickel substance of any rate of 7%, which makes the steel structure completely austenitic and gives it flexibility, a substantial size of administration temperature, non-attractive properties and great weld capacity. The scope of utilizations of austenitic tempered steel incorporates house products, compartments, modern funneling and vessels, compositional veneers and constructional structures. Austenitic evaluations are those compounds which are usually being used for spotless applications. The austenitic evaluations are not attractive. The most well-known austenitic composites are iron-chromium- nickel steels and are broadly known as the 300 arrangement. The austenitic treated steels, in light of their high chromium and nickel content, are the most consumption safe of the impeccable gathering giving uncommonly fine mechanical properties. They can't be solidified by warmth treatment, yet can be solidified fundamentally by chilly working. The
Figure 6-11 depicts the contour plots of Von Mises stress for various specific energies, as predicted by the structural analysis. The stress normal to the direction of weld on the centre of the Z axis along the X-Y plane is shown. The figure indicates that, there is a high stress magnitude for specific point energy of 50J and the magnitude of the stress reduces with a reduction in specific point energy. This is due to the fact that the stress in the structural analysis is primarily due to the thermal gradient and the same trend is noticed for thermal gradient in the thermal analysis. In Figure 6-11, the stress component is predicted to be almost zero at the side of the wall due to the applied constraints. In contrast, in the middle and towards the top surface there are large magnitudes of tensile stress. Most previous thermo-structural models [160, 238-240] use a fixed grid and assume the surface to be flat or in other words all welds to be perfectly net shaped. The variation of stress along the bead surface (Figure 6-12) and along the interface of weld-parent material found for various surface conditions cannot be predicted with the traditional model. Also, most models assume the mechanical properties of the weld to be the same as parent material, which is not the fact in reality. This model considered the actual material property of the weld bead for structural analysis. Plots of the Von Mises stress distribution along the middle the weld at mid- cross section on the X-Z plane is shown in Figure 6-12. As elucidated from the figure, increase in specific energy results in increased magnitude of the residual stress.
Galvanized iron is coated in a layer of zinc to help the metal resist corrosion. The zinc layer protected the metal by forming a physical barrier, usually around 15 μm in thickness. When using galvanized steel, no flux was required to ensure wetting of the zinc-coated steel surface. It is due to the good metallurgical compatibility between Fe, Al and Zn (Sierra, 2008). It also one of the favored as a means of protective coating because of its low cost, ease of application and comparatively long maintenance- free service life. The melting and boiling point of galvanized iron is depending on the zinc layer which coats the steel surface. The zinc layer melting point is 420 °C. (Virginia, 2010).
(d) Enable student to gain new knowledge behind the experimental research by applying fundamental of welding process and bringing the engineering knowledge to higher level especially in repair welding technology. Student will able to develop a new idea to increase the number of repair welding process in order to prolong the service cycle of the pipes.
Com base em dados da literatura [4, 5 e 6], principalmente para aços inoxidáveis austeníticos, esperavam-se maiores valores de penetração para a soldagem do aço inoxidável ferrítico com fluxo. Um dos problemas que pode ter contribuído para este comportamento, apesar dos cuidados tomados no momento da aplicação, está relacionado à homogeneidade da camada de fluxo e/ou uma fraca aderência do fluxo na chapa. Outro ponto pode estar relacionada a composição química entre metal de base com o tipo de fluxo utilizado, não gerando a convecção do fluxo (fluxo de Marangoni) como esperado. Além disso, existem também os parâmetros de soldagem, pois na literatura observa-se o emprego de correntes de soldagem mais baixas do que a empregada neste trabalho. Marya  empregando a TCD observou que a penetração tende a aumentar para as soldagens realizadas com correntes mais baixas. Deverá ser feita uma análise futura para esclarecer melhor este fato.
And those output: Residual stresses, Hardness profiles, Phase transformations, Tensile strength, Fatigue strength, Impact toughness. The output variables define a multi goal analysis and have been minimized taking into account some constraints or limitations typical of the actual process. At this stage the nodes that make up the logic flow of numerical analysis are defined. The first node is the DoE, which is the set of different designs reproducing different possible working conditions, among which the most affective ones are highlighted. Therefore it means creating a set number of designs that will be used by the scheduler (the node where the best algorithm is introduced) for the optimization. The database is built by introducing the input parameters, the corresponding output for each working condition experimentally analyzed and the physical correlations between the different conditions. The steel composition was taken into account in the calculations; the employed welding conditions are summarized in Tab. 1.
Abstract: Influence of heat input on the microstructure and mechanical properties of Shielded Metal Arc Welded (SMAW) Ferritic Stainless Steel 409 M plates was studied. Three heat input combinations designated as low heat (433.61 J/mm), medium heat (465.56 J/mm) and high heat (490.23 J/mm) were selected from the operating parameters and Bead On Plate welding was carried out. Samples prepared using these combinations were subjected to microstructural evaluations and tensile testing so as to analyze the effect of thermal arc energy on the microstructure and tensile properties. The results indicate that the samples made using low heat input exhibited higher ultimate tensile strength (UTS) than those welded with medium and high heat input. Significant grain coarsening was observed in the heat affected zone (HAZ) of all the joints and it was found that the extent of grain coarsening in the heat affected zone increased with increase in the heat input.
at the tool shoulder/workpiece and that the heat is generated by plastic deformation and shearing. The effects of different welding conditions including slow, intermediate and fast rotational tra- verse FSW speeds on stir zone (SZ) size and heat generated was studied. They found that the total heat generation for various welding conditions can be correlated with the tools radial and angular location. It is apparent that previous models are insuffi- cient to predict defects such as wormholes and voids which are cavities or cracks below the weld surface caused by abnormal material flow during welding. These defects severely weaken the mechanical properties of the welded joints . Defects are found in FSW of DH36 steel especially at high welding speeds . They are also associated with fractures in both tensile  and fatigue tests performed on DH36 steel plates [7, 8]. These defect- related failures highlight the need for the ability to predict the formation of sound welds using numerical modelling. There is also limited work on the FSW of steel to predict the stir zone (SZ) and high asymmetry between advancing and retreating sides especially for high welding speeds. Few people have succeeded in predicting the size, shape and position of the SZ using numer- ical analysis. Micallef et al.  tried to predict the SZ by deter- mining the velocity of stirring which can represent the transition between stir and no stir. However, because there is no certain value of the stirring velocity, this method can contain many er- rors. The present work models the FSW of DH36 steel by implementing a coupled thermo-mechanical flow analysis in a research Computational Fluid Dynamic CFD code ANSYS FLUENT. It uses a steady-state analysis with a Eulerian frame- work in which the tool/workpiece interfaces are in the fully stick- ing condition. In the model rotational and traverse speeds were effectively applied and the torque on the tool shoulder was mon- itored. The temperature field, relative velocity, strain-rate, shear stress on the tool surface, material flow and pressure distribution were determined by solving the 3D energy, momentum and con- servation of mass equations. The model aims mainly to predict the SZ and also the suitable rotational and traverse speeds re- quired to obtain sound weld joints. The model is validated by comparing the temperature results with thermocouples readings of a FSW sample prepared and welded at rotational and traverse speeds of 550 RPM and 400 mm/min, respectively. Metallographic examination was also carried out on the sample taken in order to compare the actual width of the heat-affected zone (HAZ) and stir zone with the CFD model predictions.
FSW of steel is expected to deliver substantial commercial and technical benefits to the marine manufacturing sector such as reduced pre-weld preparation and re-work, manpower savings, scope for redesign of assembly lines, and low distortion, high quality welds of excellent fatigue properties. In one example from FSW of aluminium, Norwegian shipyard Fjellstrand reported that “using prefabricated FSW panels has enabled a 40% increase in production capacity and turn-over at the yard”. Issues associated with setup, fixture and tooling costs along with reduced health and safety, training, consumable and material usage costs compared to conventional fusion welding techniques should also influence the introduction of this innovative welding process in industry if it can be transferred into weldingsteel. There are a number of currently identified obstacles, deeper scientific understanding of the process on steel, engagement with the shipbuilding industry, use of fillet welds, different thicknesses and joint design, which will be required to overcome before full acceptance of the process is achieved.
Therefore, it is uses to produce machine parts, chains, rivets, nails, wires and pipes (Litherland, 1999). Although the strength of the low carbon steel is not outstanding due to the composition of carbon is low but it has better formability that other types of steel would not have. Another advantages that low carbon steel had is the weld ability, this is due to the low content of carbon composition. The hardness of the steel increase with the amount of carbon content in the steel, but the probability of cracks will occurs is increasing (Weiss, 2013).
It has been known that welding process and welding consum- able have considerable effects on the performance of steel welded joints. Reddy et al. (1998) studied the resistance against projectile penetration of the HAZs and the weld metals in high- strength low-alloy steel weldments fabricated by three different welding processes. The ballistic performance of the weldments was explained on the basis of the microstructures, the hardness gradients across the weldments and the thermal efficiencies of the three welding processes. Magudeeswaran et al. (2008) investi- gated the influence of welding process and welding consumable on the transverse tensile and impact properties of armour grade quenched and tempered steel joints and reported that welding process and welding electrode significantly affect the transverse tensile strength and the impact toughness of the welded joints. However, they focused on the weld metal properties, and thus limited information on the HAZ impact toughness was provided. Moreover, in their work, the test temperature was confined to room temperature; hence the effects that welding process and welding consumable have on the low temperature impact tough- ness of structuralsteel welds are still unknown. Ren et al. (2009) explored the effects of alloying elements in welding wires and welding process on the microstructures and low-temperature impact toughness of weld metals. They indicated that optimal contents of alloying elements in welding electrode together with an appropriate welding heat input can improve the low temperature impact toughness of weld metals. However, their work was limited to the weld metal toughness of the submerged arc welded pipeline steel.