I would like to thank thermocalc software ab for preparing thermocalc. Fluid flow, inclusion removal and slag entrapment in. Slag in porosity can get there from the needle scaler, chipping hammer, etc pounding it in but is not rejectable by any provision of table 6. Slag inclusions and low carbon steel cr4 discussion thread. Slag inclusion a defect in metal intermediate and finished products made primarily by rolling or forging. As, in most cases, this defect is related to furnace or melt treatment slag it can occur in all casting materials, independent of the molding or casting process. These nonmetallic inclusions can be accompanied by gas bubbles. Absorption of nonmetallic inclusions by steelmaking slags. The phenomenon of the slag inclusion is as a results of following reasons. There are both automated and manual configurations and the solution can be optimized for the required workflow. Here are a few of the most common causes for incomplete fusion, and solutions that will help you avoid the. With the basicity r r caosio 2 by mass percent at the range of 1. For removal of oxide inclusions, a neutral slag with caosio21 or 1.
I see nothing that says any slag is acceptable on the surface only inside while doing rt or ut. If the material has been adapted instead of reproduced from the original rsc publication reproduced from can be substituted with adapted from. Steelmaking investigation on the source of surface inclusion. This optimum replacement ratio of slag is a crucial factor for its efficient use in the concrete industry. A highbasicity slag improved the cleanness of stainless steel, while a low basicity slag lowered the al2o3 content in inclusions. When the molten slag is melt the thick work piece and filler. Slag inclusions occur when slag on a previous weld pass was not removed adequately. Slag inclusion formation during solidification of steel alloys and in cast iron sofia adolfi 2007 department of materials science, royal institute of technology s100 44 stockholm, sweden abstract this thesis explores the formation of segregation and inclusions during solidification of. Click here for a printable version of the slag availability table. First, be certain to maintain the correct travel speed and angle. Slag inclusion is the small particles of flux that become trapped in the weld metal which prevent complete penetration of the weld. I have half of our instructors dead set against weaves in any form, and the other half teaching us to do them not to. The presence of manganese and silicon in the parent metal, electrode and filler wire is beneficial as they act as deoxidants combining with entrapped air in the weld pool to form slag.
Slag is one of the resources available to carry out this control. A number of factors may prevent the release of slag and. First, avoid incorrect weld bead placement, especially when making multiple passes on thick sections of metal, such as needed for the root passes of welds or wide vgroove openings. Slag can never be fully prevented, but with a few steps it can be managed. The copper can melt away and become trapped in the finished weld. Describe the difference between using s leading and a trailing electrode angle. Welds with incomplete fusion are weak and substandard welds at best if not downright dangerous. Corrosion of aluminium on the autoclaves technical report. The most common is slag, a nonmetallic solid material trapped in the weld or between the weld and the base metal. A slag inclusion can show up anywhere in the weld, root, crown, or in the fill. This paper proposes a numerical procedure to analyze the optimum usage of slag for the compressive strength of concrete.
State key laboratory of advanced metallurgy, university of science and technology beijing. Analysis of the optimum usage of slag for the compressive. Welding into a v joint that is to narrow also causes slag inclusion. Incomplete fusion is a lack of penetration or fusion between the weld metal and the parent metal of the piece. Mar 29, 2014 best practice the following techniques can be used to prevent slag inclusions. Slag particles tend to get caught in hollows and sharp angles. Its original intent was to consolidate titanium castings revert and loose titanium scrap into electrodes for melting in consumablearc furnaces. Chemical reactions can occur between molten metal and its surroundings reactions can lead to defects in the final castings metal oxides may form when molten metal reacts with oxygen dross or slag is the material that can be carried with the molten metal during pouring and filling of the mold. One of the most common causes of slag inclusions is the presence. How do you prevent the occurrence of slag inclusion and undercut. If slag is not properly removed, it can lead to slag inclusions in the weld. Synthetic slag for secondary steelmaking ispatguru. Concrete proportioning is the selection of proportions of ingredients to make the most economical use of available materials to produce concrete of the required properties why use slag cement in concrete. Aldeoxidation during tapping process, with slag of high basicity, high al2o3 content and low oxidizing property, al2o3 inclusions, which are the product of aldeoxidation could transform to mgoal2o3 spinel, and later on to caomgoal2o3 inclusions of lower melting point, which are inclined to be eliminated by floatation, thus total oxygen.
If youre using a copper backing bar and you want to avoid slag inclusions, keep a close. Causes as slag is the residue of the flux coating in mma welding, it is principally a deoxidation product from the reaction between the flux, air and surface oxide. This defect is often observed on casting surfaces on top in the mold, cores, and protruding mold sections. Steelmaking investigation on the source of surface. Moreover correct current, voltage and good arc characteristics are essential elements, to produce smooth and quality welds with complete fusion among multipass runs. Welding defects can be defined as weld surface irregularities, discontinuities. If theres serious rusting on the surface of the weld then you have no chance of recognising just how bad the surface inclusions are. Industrial uses of slagthe use and reuse of iron and steelmaking slags 57 introduction throughout the ages, slags have been used to refine metals. Metallurgy of original 1800s bowie knife made by james black. Nov 11, 2017 i it can be prevented by producing large areas with wavy, corrugated construction, or add sufficient riblike shape, to provide equal cooling rates in all areas.
This can result in a weakened condition which could impair the serviceability of the component. Slag inclusions are elongated accumulations of nonmetallic inclusions, from several millimeters to several centimeters in length. Slag is an industrial waste product there is no standards about the quality of it. Slag is normally seen as elongated lines either continuous or discontinuous along the length of the weld. Effect of slag control on steel process optimization and. Of the three, cracks are by far the most detrimental.
These are called inclusions and are a form of welding defect. Evaluation of inclusion composition during the ladle refining have revealed that the majority of the inclusions belonged to the system al2o3caomgosio2 and. Apr 02, 2020 in multilayer welding operations, failure to remove the slag between the layers causes slag inclusions. A welds ductility may decrease with a high carbon equivalent and a high cooling speed after solidification. How do you prevent the occurrence of slag inclusion and. In fact, slag inclusions are often associated with incomplete fusion.
Common mistakes to avoid in pipe welding interesting engineering. Apr 26, 2017 this can result in a weakened condition which could impair the serviceability of the component. The extruded speed should be controlled effectively. A thin projection of metal, not considered as a part of casting is called as fins or fin. Rimming steels with a high oxygen content, can only be welded satisfactorily with a consumable which adds aluminium to the weld pool. Oct 27, 2016 weld cameras are also useful in identifying inclusions. These weld defects often result from surface contaminants that become mixed into the weld pool and are trapped during solidification. Welding current density is too small,which is difficult to provide enough heat for molten metal and it leads to the fact that slag might be impossible to float on the weld surface. Slag, steel, ladle and nonmetallic inclusions equilibria.
Chengsong liu1, 2, shufeng yang1, 2, jingshe li 1, 2, xiaojie gao1, 2, linzhu wang1, 2 1. Laboratory experiments and thermodynamic calculation for the sideoxidized 18cr8ni stainless steel with caoal2o3sio2caf2mgomno slag were performed to investigate the effect of slag composition on inclusions in sideoxidized 18cr8ni stainless steels. From byproduct to valuable construction material by stephen dietz 07. Enough discard pressure should be kept, too much will lead aluminium into the profile end and cause black trail and slag inclusion. Have found the weld has to ground out to do a proper job of re welding. The following techniques can be used to prevent slag inclusions. Quizlet flashcards, activities and games help you improve your grades. The problem with crucible steel is p and s impurities, because free p and s atoms can travel in steel matrix. Copper backing bars are another common source of slag inclusions. However, after an optimum point, any further increase in slag does not improve the lateage compressive strength. A casting defect is an undesired irregularity in a metal casting process. Fluid flow, inclusion removal and slag entrapment in molten steel continuous casting mould.
Among the steps that will help manage the problem are. Better welding second, since the esr process has a considerable capability for the removal of large refractory or slag inclusions, the use of complex filters and tundish arrangements in the vim can be minimised. Nonmetallic inclusions in steel quantitative analysis using correlative microscopy. Slag cement benefits and use in concrete slag cement news.
Sep 27, 2011 please use one of the following formats to cite this article in your essay, paper or report. Normally, this is discovered during machining operations, at which point in the process it can be very expensive to resolve. The las x steel expert software from leica microsystems combined with a leica microscope offers a rapid and flexible, solution for rating the quality of steel in terms of inclusions. Her stories give insights into the world of the voestalpine group. In multipass welding applications, slag that is not completely removed between passes can be a source of inclusions. Chengsong liu1, 2, shufeng yang1, 2, jingshe li 1, 2, xiaojie gao1, 2, linzhu. Here we have discussed about what is casting defects types, causes and remedies to eliminate it. Slag is used all over the world in road and railway construction and for engineering, and has many advantages over natural rock. Remedies to prevent slag inclusions avoid atmospheric contamination using proper welding procedure e. Slag inclusion is a type of welding defect that is easily visible in the weld. Slag inclusions american welding society education online. Slag inclusions occur when the slag gets trapped inside of the weld metal, which could weaken weld components and reduce serviceability. The most common cause of slag inclusions is failure to completely remove the slag from one weld pass before making another. Also, both a negative effect of these wastes on the environment and financial losses are prevented.
Removing slag requires the use of a chipping hammer or wire brush, and can be easier or harder, depending on the type of electrode coating. In concrete, slag cement may be proportioned from 20 to 80 percent depending on the application. Holds editorial responsibility for blog topics, is researching and writing articles. It is also important to use the correct welding method and to avoid the use of excessively thick electrodes in confined joints.
What is the best way to reduce the occurrence of slag and dross in ductile iron. Ive heard so many theories about weaves vs stringers and i still dont know what to believe. The other aspect concerns the physical aspects related is the slag ability to capture the inclusions. Yields, however, decrease because of poor slagmetal separation. The electroslag welding esw process, the metal coalescence produced by molten slag. Study of the suitability of different types of slag and its. Slag cement is commonly found in readymixed concrete, precast concrete, masonry, soil cement and high temperature resistant building products. Learn vocabulary, terms, and more with flashcards, games, and other study tools. Cracks in a weld, or in the vicinity of a weld, indicate that one or more problems exist that must be addressed. Slag study guide by bryonipeek includes 6 questions covering vocabulary, terms and more. Slag inclusions can be produced in a reproducible manner for fatigue testing. Slag is a nonmetallic component that exists in the weld, on the surface or between layers. Downloadable and printable versions of this data may be obtained.
Effect of the top slag on the inclusions chemistry can be predicted with accuracy, and hence it is possible to control the inclusions chemistry through proper design of the top slag composition so. The motion behavior of nonmetallic inclusions at the interface of molten steel and slag fundamentally affects the removal of inclusions. If youre using a copper backing bar and you want to avoid slag inclusions, keep a close eye on your penetration weld depth dont make the weld too deep. The concerns with slag recycling are that first, because slag can contain environmentally hazardous materials, it must be analyzed for elemental composition before reuse. The properties of the slag produced during steel making depends on many factors, mainly the manufacturing process.
Slag, steel, ladle and nonmetallic inclusions equilibria in an aseaskf ladle furnace kamrooz riyahimalayeri. I have tried to find a picture on the, showing a linear slag inclusion open to the surface, and found it on a german car mechanics website. In this article, we will examine arc blow and discuss ways to troubleshoot and eliminate this phenomenon to create a better weld. A number of factors may prevent the release of slag and result in the slag being trapped in the weld metal. Like incomplete fusion, slag inclusions can occur between the weld and base metal or between individual weld passes. Some of these factors are 1 high viscosity weld metal 2 rapid solidification 3 insufficient welding heat 4 improper manipulation of the electrode 5 undercut on previous passes. I interpret that to say no slag is acceptable on the surface. Slag inclusions are nonmetallic particles trapped in the weld metal or at the. Usually used in reference to a lady who has a revolving door to her bedroom. These cavities are the primary source of slag inclusions in your weld.
Some defects can be tolerated while others can be repaired, otherwise they must be eliminated. If you find any query regarding this post feel free to ask. Mar 07, 2011 slag inclusions can be prevented in several ways. In a simplified point of view, an evaluation of the feasibility of the passage of the oxide inclusions from liquid steel to slag has been studied. Material and method representative converter slag cs sample was supplied by eti copper inc.
Preparing the groove and weld properly before each bead is deposited. In steelmaking, it is generally understood that inclusions are naturally absorbed by slag when flotation is sufficient. Slag remaining after slag removal procedures, usually from overlap or incomplete fusion. Slag inclusions occur due to the welders failure to maintain a molten condition for long enough to float out all foreign material from the weld. Industrial uses of slagthe use and reuse of iron and. Slag inclusions are usually associated with the flux processes, ie mma, fca and submerged arc, but they can also occur in mig welding. It is also important to use the correct welding method and to avoid the use of. There are many others, but slag is in fact possible to find on the surface. Especially at the end of aluminium bar, the speed should be slow down, to prevent impurities getting in with turbulent flow. Induction slag melting ism was developed by the bureau in the 1970s as a technique for vacuum induction melting titanium in a segmented copper crucible. There seems to be alot of talk lately about slag inclusions or metal having a grain direction. Slag inclusion article about slag inclusion by the free. After completing this chapter, the student should be able to set the welding amperage correctly.
Slag inclusion formation during solidification of steel. Dross or slag is the material that can be carried with the molten metal during pouring and filling of the mold. The nozzle play asignificantrole for controlling flow pattern in mold, therefore, by. As youre welding, youre likely to encounter slag inclusions foreign materials trapped in the weld metal at continuous or randomly spaced intervals. Second, care must be taken to improve slag potential for other purposes without. Use welding techniques to produce smooth weld beads and adequate interrun fusion to avoid forming pockets to trap the slag use the correct current and travel speed to avoid undercutting the sidewall which will make the slag difficult to remove remove. Effect of top slag with low basicity on transformation. When welding in the verticalup position, keep your guns drag angle between 5 and 15 degrees and increase it as necessary if the problem still occurs. Welding slag is a form of slag, or vitreous material produced as a byproduct of some arc. This defect can be prevented by reducing the gap with good fixturingclamping. Though less common, slag may also be applied to males. Welds may contain porosity, slag inclusions or cracks.
Slag inclusion formation during solidification of steel alloys and in cast iron sofia adolfi 2007 department of materials science, royal institute of technology s100 44 stockholm, sweden abstract this thesis explores the formation of segregation and inclusions during solidification of steel and cast iron. It is something else that someone is seeing, while i can t comment on what exactly it is, i can almost certainly guarantee that it isnt slag. Chapter 11 fundamentals of casting flashcards quizlet. Scoping experiments indicate that massive pieces of uranium, comprising as much as 7% of the greensalt ufsub 4 charge, can be remelted in the 4kg dingot bomb with no loss of metal quality. Effect of slag composition on inclusion control in lfvd. Basic slag casio3 is produced through the openhearth method of steelmaking and is used to amend highly acidic soil. The health risk of slag an industrial waste product. Slag inclusions and oxide film in ductile cast iron in the canisters slag inclusions in 40crmnmos86 steel slag inclusions in gx2crnimo18143 cast steel slag inclusions in gx3crnimon175 cast steel slag inclusions in x12cr steel slag inclusions in x19nicrmo4 steel slag inclusions in basic bessemer steel. The gases produced push the atmospheric gas back, preventing oxidation and reactions. However, you can avoid these errors to a large extent by keeping these. The formation of nonmetallic inclusions during steelmaking is inevitable and, when not properly controlled, can cause performance and production problems. Kodi archive and support file community software vintage software apk msdos cdrom software cdrom software library console living room software sites tucows software library shareware cdroms cdrom images zx spectrum software capsules compilation doom level cd. Solid inclusions that impair weld characteristics welpedia. A study of slagsteelinclusion interaction during ladle.
These tips and tricks can help avoid the temptation. Use welding techniques to produce smooth weld beads and adequate interrun fusion to avoid. There are four major causes of slag inclusions, all of which can be prevented with proper welding techniques. Investigation on the source of surface inclusion defects in sphc hot rolled coils by slag tracer method. Dec 02, 2017 but when raw materials are melted in crucible slag floats and steel is quite pure from slag inclusions, and in this case, forging can not further reduce slag content. Its phraising effect is similar to that of ground limestone.
Whereas there are acceptable limits for slag inclusions and porosity in welds, cracks are never acceptable. Residual stress in a weld can be larger than expected if it contains weld discontinuities such as incomplete fusion, incomplete joint penetration, overlap, undercut, slag inclusions, and porosity. Slag inclusions can show up in nondestructive testing and often are caused by. Synthetic slag basically consists of calcium aluminates which are the salts of aluminic acid and calcium hydroxide. Weldability of materials carbon manganese and low alloy steels. Arc blow can cause a number of welding problems, including excessive spatter, incomplete fusion, porosity and lower quality. Journal of multidisciplinary engineering science studies. If the metal has been mig welded with flux cored wire the hope is that all the slag will be on top where it can. Uranium scrap metal can be recovered on a laboratory scale by recycling to reduction bombs. Defects imperfections in welds slag inclusions twi. In multilayer welding operations, failure to remove the slag between the layers causes slag inclusions. About 200 simulation cases were modeled and solved by the finite element software. What is in it depends on what was the raw material used for the production of iron e. While there are many applications and benefits of slag cement, a few are highlighted below and detailed information sheets are located here.