The forming mechanism of fusion zone polygonal porosity and heat affected zone haz liquation cracking were systemically investigated and possible solutions to the welding process were also proposed. The authors emphasize fundamental metallurgical principles governing microstructure evolution and. Contribution to haz liquation cracking of austenitic. A concern, when welding the austenitic stainless steels, is the susceptibility to solidification and liquation cracking. Stainless steels are more resistant to general corrosion compared with carbon steel. With regard to the safe temperature for carbon steel, the reader should look at the curve in figure 1. Highly crack susceptible alloys 2024 and 7075 were welded using gasmetal arc welding gmaw with filler metals 1100 and 4043, respectively. Liquation is a metallurgical method for separating metals from an ore or alloy. This method was largely used to remove lead containing silver from copper, but it can also be used to remove antimony minerals from ore, and refine tin.
Two main cracking mechanisms, liquation cracking and solidification cracking that are very common during welding of nickelbased superalloys, have been identified in. Practical solutions by solutions for people, processes and paper. Further, liquation cracking during welding20 and liquid metal embrittlement40 are also assumed to occur intergranularly. Almost all metals such as carbon steel, lowalloy steel, austenitic stainless steel, nickel alloy, and aluminum alloy may, on any scale, suffer this defect. In order for heat affected zone cracking to occur, three. Optimized heat treatment of 347 type stainless steel. For example, on 304 series austenitic stainless steel, you should use an er308 rod see figure 1 for additional options and exceptions. Welding metallurgy and weldability of stainless steels, the first book in over twenty years to address welding metallurgy and weldability issues associated with stainless steel, offers the most uptodate and comprehensive treatment of these topics currently available. During laser welding of stainless steel to copper, cu atoms permeates promptly along the grain boundary because of a small resistance. Accomplish the impossible with integrity intelligence tuesday, march 10, 2020 10. The material must be heated until one of the metals starts to melt and drain away from the other and can be collected. Liquation cracking during the welding of austenitic stainless steels.
Solidification and liquation cracking issues in welding springerlink. In this study, we present experimental laser welding sus304 stainless steel to t2 copper. Both solidification cracking and hot cracking refer to the formation of shrinkage cracks. Hot cracking or high temperature cracking in the weld fusion zone and the haz is called solidification cracking and liquation cracking, respectively. Information on certain aspects of avoiding solidification cracking in a variety of weldable materials is given in the job knowledge series. Austenitic stainless steel duplex stainless steel heataffected zone varestraint testing cracking susceptibility calculated fn grain boundaries microstructure segregation ivtechanism fp austenitic stainless steel. Formation, quantification and significance of delta. It could be diminished by small increase in carbon, nitrogen, chromium, nickel, and silicon or by substantial increase in manganese content 55. Liquation cracking can occur during fabrication by welding in either the heat affected zone in the parent material, or in previously deposited weld metal during. Heataffected zone liquation cracking in austenitic and duplex. Liquation cracking in the partially melted zone pmz of fullpenetration aluminum welds was investigated, using the simple binary alloy 2219 al6. The deposition of carbon steel or lowalloy steel filler metal on austenitic stainless steel can result in hard, brittle weld deposits. Following an outline of the material classes and circumstances in which it is most likely to occur, compositional influences in austenitic stainless steels and nickel alloys are considered in more detail. Hot cracking is also known as hot shortness, hot fissuring, solidification cracking and liquation cracking.
Also see here for information on the susceptibility of ferritic stainless steels to hot cracking. Heataffected zone liquation cracking in austenitic and. However, after service exposure this alloy exhibits problems with liquation cracking in the base metal heataffected zone haz during repair welding. Effect of weld metal copper content on haz cracking in. Hot cracking is the formation of shrinkage cracks during the solidification of weld metal. Solidification and liquation cracking issues in welding. The effect of liquation cracking on toughness levels in mig welds made in. Cold cracking is much worse than hot cracking simply because it may be hours or days before the crack appears. Cracks can occur in various regions of the weld with different orientations, such as centerline cracks, transverse cracks, and microcracks in the underlying weld metal or adjacent heataffected zone haz. Mar 12, 2017 lec 35 metallurgical transformations in weld and heat affected zone of steels duration.
In the present study, specimens of dissimilar metals made from austenitic stainless steel and al brass were welded by the gtaw process using four different filler metals. If you have any comments or questions about the glossary, please contact dan davis, editorinchief of the fabricator. For reformer outlet manifolds, a cast, heatresistant stainless steel with the composition 20cr32ni1nb astm a351 grade ct15c is widely used. Weldability and liquation cracking characteristics on resistancespotwelded highmn austenitic steel dulal chandra saha,yeongdo park department of advanced materials engineering, graduate school of engineering, dongeui university, busan 614714. The pmz is the region immediately outside the fusion zone where the material is heated above the eutectic temperature. Hot cracking is also known as solidification cracking, which occurs in weld metals when a molten weld metal freezes, and liquation cracking, which occurs in the heataffected zones of the mother metal and weld metal in solid, affected by the heat of the arc. Similarly, the process of liquation cracking, or cracking along the liquid channels between grains, also known as intergranular failure, is. Preweld and interrun cleaning was achieved using a stainless steel wire brush. Solidification and liquation cracking issues in welding, jom.
In aluminum alloys, fully austenitic stainless steels, nibased alloys, etc. The heat affected zone crackingtendency of type 347 stainless steel was evaluated in five different samples of thick walled pipe or plate differing in nb. Austenitic stainless steel a fully austenitic stainless steel weld is more prone to cracking than one containing between 510% of ferrite. Typically, austenitic stainless steel filler rod is available in diameters from 0. Hot cracking may occur because of low melting point impurities such as phosphorous p and sulfur s. Stainless steel welding is a complex mixture of metallurgy, chemistry. Welding research liquation cracking in fullpenetration alcu. As shown previously, huang and kou liquation can occur in the pmz, making it miyazaki et al. Examples of such cracking in laserwelded a2090 aluminum alloy are shown in fig. Weld heat affected zone liquation cracking in type 347 stainless steel. Liquation cracking, on the other hand, can occur in the partially melted zone during the solidification of the liquated material. Transgranular liquation cracking of grains in the semi. Two main cracking mechanisms, liquation cracking and solidification cracking that are very common during welding of nickelbased superalloys, have been identified in these studies 3,6,7,10,12,19. Apr 20, 2003 as shown previously, huang and kou liquation can occur in the pmz, making it miyazaki et al.
Hot ductility and hot cracking behavior of modified 316. Failures in stainless steel welds examples and causes. This is the first time transgranular liquation cracking tlc has been observed in situ and quantified in semisolid alloys, similar. Similarly, twip steels which also has an austenitic microstructure, has been found to be susceptible to cracking. Stress corrosion cracking scc is the growth of crack formation in a corrosive environment. However, after service exposure this alloy exhibits problems with liquation cracking in the base. Stabilization heat treatment of austenitic stainless steel. This allows keywords aluminum alloy 2219 solidification cracking liquation cracking partially melted zone circularpatch test scheil equation liquation cracking in fullpenetration alcu welds. This csr was experimentally verified using longitudinal and spotvarestraint tests performed on a286 and type 310 stainless. This means the welded assembly may already be out the door and in service. Cracks have been observed mostly in the mode of solidification crack hot crack, and liquation crack. Highnickel alloys abrass aluminum alloys titanium alloys magnesium alloys zirconium alloys environment hot nitrate, hydroxide, and carbonatebicarbonate solutions. However, the cathodic behavior of the austenitic weld deposit may increase the susceptibility for stresscorrosion cracking scc in the haz of the highstrength steel. The authors emphasize fundamental metallurgical principles governing microstructure evolution and property development of.
Welding metallurgy and weldability of stainless steels. Solidification cracking can occur in the fusion zone during the solidification of the weld metal. Fatigue cracking of a 316l stainless steel nozzle sleeve from a chemical processing vessel. Investigation on effect of welding parameters on solidification cracking of austenitic stainless steel 314. Liquation cracking in reheated regions of austenitic weld metal may be known by a number of terms, specifically microcracking or microfissuring, and can occur in weld metals of all the 300 series stainless steels, e. Solidification and liquation cracking issues in welding request pdf. Both solidification cracking and hot cracking refer to the formation of shrinkage cracks during the solidification of weld metal, although hot cracking can also refer to liquation cracking solidification cracks can appear in several locations, and. Weldability and liquation cracking characteristics on. Highly cracksusceptible alloys 2024 and 7075 were welded using gasmetal arc welding gmaw with filler metals 1100 and 4043, respectively. A fully austenitic stainless steel weld is more prone to cracking than one containing between 510% of ferrite. Liquation cracking model a crack incubation, b crack initiation, c crack growth. Forensic failure analysis, corrosion investigation, metallurgical testing and engineering located in mooresville, nc. Welding research liquation cracking in fullpenetration. Cracks initiated at intergranular corrosion penetrations propagating by corrosion assisted fatigue.
Location of liquation cracking indicated by arrows. Stress relaxation study of haz reheat cracking in type 347. Titanium compounds have been found to cause liquation cracking in maraging steels and titanium containing stainless steels and superalloys. The beneficial effect of ferrite has been attributed to its capacity to contain harmful impurities within the grains which would otherwise form low melting point segregates and consequently interdendritic. Scc is highly chemically specific in that certain alloys are likely to undergo scc only when exposed to a small number of chemical environments. It can lead to unexpected sudden failure of normally ductile metal alloys subjected to a tensile stress, especially at elevated temperature. Avesta welding ab is part of a group that is at the forefront of stainless steel technology. Types 321 and 347 stainless steels are the alloys most commonly thermally stabilized, but these alloys are also susceptible to weld and haz cracking problems during these heat treatment procedures, i. Liquation cracking in the partially melted zone pmz of aluminum welds was studied. Liquation cracking during the welding of austenitic. Liquation cracking can occur during fabrication by welding in either the heat affected zone in the parent material, or in previously deposited. Liquation cracking, on the other hand, can occur in the p. Unexpected corrosion of stainless steel in high solids.
Weld heat affected zone liquation cracking in type 347. Austenitic stainless steel has good weldability but is sensitive to hot cracking such as solidification and liquation cracking. Evaluation of the potential for weldrelated cracking in. Both solidification cracking and hot cracking refer to the formation of shrinkage cracks during the solidification of weld metal, although hot cracking can also refer to liquation cracking solidification cracks can appear in several locations, and orientations, but most commonly are longitudinal centreline cracks coincident with the intersection of grains growing from opposite. Heataffected zone liquation crack on resistance spot welded. Dec 19, 2019 hot cracking is the formation of shrinkage cracks during the solidification of weld metal. Unexpected corrosion of stainless steel in high solids black liquor service. Cold cracking is characterized by a crack starting on the base material and not on the weld as is the case with hot cracking. Namely the thermorestorw test with temperaturestrain simulation of welding cycles japanese and the ltp16tig test russian were employed. Heataffected zone liquation crack on resistance spot. Designed to aid the selection of the most appropriate consumables and methods for welding stainless steels, it is hoped that the avesta welding manual reflects this position. A 40% thermal expansion mismatch between the austenitic stainless steel and ferritic base metal produces a signi. The thermal csr was theoretically derived based on the ductility of a material during welding as obtained from the gleeble hotductility test and the criteria assumed in the development of liquation cracking theories.
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