Stress corrosion cracking scc is characterized by cracks propagating either transgranularly or intergranularly along grain boundaries. Stress corrosion cracking scc is the growth of crack formation in a corrosive environment. Hydrogeninduced cracking hic in steel is a risk problem when steels are charged with hydrogen in service as in various hydrogen sulfide environments like sour oil and gas wells and some power plants. Hydrogen induced stress cracking susceptibility of hyper. Damage due to hydrogen embrittlement and stress corrosion. Mechanisms that have been proposed to explain embrittlement include the formation of brittle hydrides, the creation of voids that can lead to bubbles and pressure buildup within a material and e. Hydrogen induced cracking steel features, applications. Hydrogen induced stress cracking hisc resistance and improvement. Hic test, hydrogen induced cracking test, step wise cracking. Hydrogen induced stress cracking hisc resistance and. Intergranular cleavage fractures are often difficult to distinguish from cracks that have been formed by intergranular stress corrosion cracking. Hic test apparatus is supplied with essential spares for uninterrupted long term testing. The results showed that the failure developed from a combination of factors, typical for hydrogeninduced stress cracking. Another type of hydrogen corrosion, stressorientated hydrogen induced cracking sochic, is normally found in the base metal adjacent to the weld, where the stress point is highest due to the internal pressure of the.
Hydrogen induced damage can reveal fracture surfaces that cannot be easily distinguished from cleavage fractures. Hic test, hydrogen induced cracking test, step wise. Also known as sour service, issues including hydrogen blistering, hydrogen induced cracking hic and stress orientated hydrogen induced cracking sohic are caused by the aqueous hydrogen charging of the steel. Even though hics and sohics have similar names, they are two completely different mechanisms. Ferritic stainless steels, on the other hand, tend to be fairly resistant to hydrogen stress cracking due to their comparatively low hardness. Hydrogeninduced phase transformation was studied by xrd. This can occur during elevatedtemperature thermal treatments and in service during electroplating, contact with maintenance chemicals, wet h 2 s, corrosion reactions, cathodic protection, and operating in highpressure hydrogen containing environments. Hydrogen induced stress cracking of materials under. Together with my phd student sofia hazarabedian and my colleagues andy viereckl, garry leadbeater, zak quadir, vlad golovanevskiy, skjalg erdal, and paul georgeson, we recently published a comprehensive rootcause analysis and thorough hydrogeninduced stress cracking investigation of swaged 25cr super duplex connectors this work focuses on two connectors used in. Vargas pm, wastberg s and woollin p, stress based design guidelines for hydrogen induced stress cracking hisc avoidance in duplex materials, proc conf omae 200979504. Hydrogen induced stress cracking civilweb spreadsheets. Hydrogen induced cracking hic is a failure mechanism resulting in sudden exposures and cracks due to growing laminations inside the base material and welds. Stress corrosion cracking and hydrogen embrittlement of.
Hydrogen induced cracking hic damage is a degradation mechanism active in the oil and gas industry. Hydrogen induced plasticity in stress corrosion cracking. Hydrogen induced cracks either follow a linear or stepwise path within the material, hence the term stepwise cracking. Hic usually occurs due to the effects of aqueous hydrogen charging of steel in wet h2s refinery process. General aspects hydrogen embrittlement is usually understood as the unwanted delayed brittleness of a material fig. Hydrogen induced cracking hic from advanced ndt solutions. Several failure investigations and extensive testing have been carried out over the last 510 years. The methane molecules create a pressure which leads to embrittlement and even cracking of the metal. Hydrogen induced cracking of subsea duplex stainless steel twi. More often, fracture occurs at sustained loads below the yield strength of the material. Hydrogen induced cracking steel features, applications and. Jul 29, 2019 hydrogen induced cracking failures of sour gas processing equipment and transmission pipelines have been reported at facilities in libya, saudi arabia and other middleeastern plants. Also high strength structural steels which are welded are exposed to a certain hydrogen pickup which means a risk at fracture and blistering due to hic. The failure of highstrength fasteners in aerospace equipment as a result of scc or hsc occurs infrequently and almost always unexpectedly.
Request pdf modelling hydrogen induced stress corrosion cracking in austenitic stainless steel a model has been developed which simulates the deformation of single crystal austenitic stainless. Modelling hydrogen induced stress corrosion cracking in. Hic test specimens are machined with thickness of 530mm, width 20mm, and length of 100mm is suitable for testing as per the nace standard. This charging can cause blistering and embrittlement, which is potentially disastrous in carbon steel pressure vessel environments. In this issue, the characteristic features and principal causes of hydrogen cracks are described. The term environmental stress cracking1 failures is also used sometimes. Hydrogen induced cracking hic is a common form of wet h2s cracking caused by the blistering of a metal due to a high concentration of hydrogen. The hydrogen is first produced as hydrogen atoms h which normally combine rapidly to form hydrogen molecules h 2. Hydrogen combines with carbon within the alloy and forms methane. Hydrogeninduced cracking hic is a far too common type of failure. Hydrogen induced cracking test apparatus is rectangular provided with ready to use connections fittings.
Hydrogen induced stress cracking hisc rolled alloys, inc. As we know that both form of cracking are due to the absorption of atomic hydrogen that is produced by. Stress corrosion cracking and hydrogen embrittlement of high. Hydrogen induced stress cracking hisc of stainless steels under. Hic is especially prevalent in iron alloys because of the restricted slip capabilities in the predominantly bodycentered cubic bcc structure. Sulfide stress cracking is a function of hydrogen sulfide concentration as low as ppm, hydrogen sulfide partial pressure, stresses, material yield strength, temperature and ph. Ferriticaustenitic duplex stainless steels should be regarded as potentially susceptible to hydrogen induced stress cracking, independent of smys typically 400 to 550 mpa or specified maximum hardness. Astm f519 hydrogen embrittlement he testing element. The susceptibility to hisc has been confirmed in these materials. Hic steel hydrogen induced cracking supplier company. Hydrogen induced stress cracking hisc of duplex material 1 day.
Two heat treatments of the aisi 4340 material were used as a standard for two levels of yield strength. Hydrogen induced stress cracking hisc and dnvrpf112 and increase the risk for brittle fracture of the material. Welding may cause increased hydrogen induced stress cracking susceptibility in the weld metal and in the haz adjacent to the fusion line. It involves the ingress of hydrogen into a component, an event that can seriously reduce the ductility and loadbearing capacity, cause cracking and catastrophic brittle failures at stresses below the yield stress of susceptible materials. Hydrogen embrittlement he also known as hydrogen assisted cracking hac and hydrogeninduced cracking hic. Hydrogen induced stress cracking in uns s32750 super duplex. Hydrogen induced cracking failures of sour gas processing equipment and transmission pipelines have been reported at facilities in libya, saudi arabia and other middleeastern plants. In the case of a crystal lattice becoming saturated or coming into contact with atomic hydrogen, many alloys and metals may. It is characterized by the brittle fracture of a normally ductile alloy under sustained load in the presence of hydrogen. The measured hydrogen content in parts of the material exceeded 40 ppm, more than an order of magnitude higher than what is normally expected in super duplex stainless steels. The principal distinguishing feature of this type of crack is that it occurs in ferritic steels, most often immediately on welding or a short time after welding. General aspects hydrogen embrittlement is usually understood as the unwanted delayed brittleness of.
Hydrogen embrittlement of aisi 4340, inconelrtm 718, alloy 686 and alloy 59 was studied using slow strain rate tests of both smooth and notched cylindrical specimens. The ssc of medium strength steels has been a continuing source of trouble in the oil fields, and from these troubles has evolved in international standards 6. Susceptibility to hydrogen blistering and hydrogen induced cracking can be apportioned to the quality of the steel plate used. Stressoriented hydrogeninduced cracking, called sohic, is treated in api 579 like cracks. The hydrogen atom is the smallest of all atoms and hydrogen attack is similarly insidious and hidden from simple inspection techniques. This penetration can lead to the brittle fracture of materials that are normally ductile when hydrogen happens to be present in their environment. Hydrogeninduced cracking susceptibility in highstrength. It is a complex process that is not completely understood because of the variety and complexity of mechanisms that can lead to embrittlement. Sulfide stress cracking ssc vs hydrogen induced cracking. The hydrogeninduced cracking hic susceptibility of weld met als of hightensile strength ranging from 70 to 100 kgfmm2 100 to 143 ksi was investigated to estimate the lowest possi ble preheat and interpass temperatures to prevent cracking.
Hydrogen embrittlement also known as hydrogen assisted cracking and hydrogeninduced cracking, describes the embrittling of metal after being exposed to hydrogen. Hydrogen induced cracking results from atomic hydrogen being absorbed by solid metals. Aug 01, 2019 thus, the three causative factors promoting hydrogen induced stress cracking, namely, a susceptible microstructure, a hydrogen bearing environment, as well as sufficiently high applied and residual stresses in the material were the focus of this investigation. Hydrogeninduced damage can reveal fracture surfaces that cannot be easily distinguished from cleavage fractures. There are several types of stress corrosion cracking scc, for example, chloride induced scc and h 2 s induced scc. A small number of duplex and superduplex stainless steel components have failed in subsea service due to hydrogen induced stress cracking hisc. The results showed that the failure developed from a combination of factors, typical for hydrogen induced stress cracking. This hisc course is based on dnvglrpf112 duplex stainless steel design against hydrogen induced stress cracking. Scc is highly chemically specific in that certain alloys are likely to undergo scc only when exposed to a small number of chemical environments. Sulfide stress cracking ssc vs hydrogen induced cracking hlc posted in refining, hydrocarbons, oil, and gas. Processes or conditions involving wet hydrogen sulfide, i. Hisc is a term to refer to hydrogen stress cracking hsc of duplex and super duplex stainless steels dss and sdss, respectivelywhen exposed to hydrogen generated by cathodic.
Hydrogeninduced cracking hic is the stepwise internal cracks that connect adjacent hydrogen blisters on different planes in the metal, or to the metal surface. Hsc is a form of environmentally assisted cracking in which a ductilealbeit susceptiblematerial could exhibit fast brittle failure when exposed to hydrogenbearing environments under particular loading conditions. Hydrogen stress cracking is a form of hydrogen embrittlement that occurs when corrosion from acids like wet hydrogen sulfide and hydrofluoric acid cause atomic hydrogen to penetrate hardened or higher strength steels and cause stress cracking. The brittle nature of the fracture surface, calcareous deposits on the ferrule and exposure to cathodic protection suggested hydrogen induced stress cracking hisc.
Experience has shown that stainless steels can suffer from hydrogen induced stress cracking hisc under cathodic protection in seawater. Stress oriented hydrogen induced cracking sohic stress orientated hydrogen induced cracking occurs in the area of grain enlargement in weld heat affected zones. Hydrogen stress cracking can affect several different types of metals such as high strength structural, carbon, and low alloy steels, along with titanium, nickel, and aluminium alloys. The following paragraphs deal with this subject from a failure analysis point of view. Hydrogen stress cracking is a form of embrittlement occurring when corrosion from certain acids causes atomic hydrogen to penetrate higher strength steels. Hic usually occurs due to the effects of aqueous hydrogen charging of steel in wet h2s refinery process environments. Hydrogen induced stress cracking hisc and dnvrpf112. It primarily occurs in high strength low alloy steels. There is a growing acceptance of the term scc to co\er both mechanisms. This paper presents results from a test program examining the hisc susceptibility of 25% cr super duplex stainless steel uns s32750 at. Factors influencing hydrogen induced cracking welding.
However, under certain stress and material conditions, the cracks can be arranged in a ladderlike array known as stress orientated hydrogen induced cracking sohic. Hydrogen induced cracking hic when corrosion of steel occurs in an acid solution e. Hydrogeninduced cracking and blistering digitalrefining. To date only duplex stainless steels, together with supermartensitic stainless steels, have been extensively tested. Hydrogeninduced stress cracking of swaged super duplex. Hydrogen induced stress cracking of duplex stainless steel. Proceedings of the asme 2010 29th international conference on ocean, offshore and arctic engineering. Sulfide stress cracking is the worst type of corrosion in the presence of hydrogen sulfide.
Processes or conditions involving wet hydrogen sulfide i. Hydrogen induced plasticity in stress corrosion cracking of. Hydrogen induced cracking hic refers to the internal cracks brought about by material trapped in budding hydrogen atoms. Corrosionpedia what is hydrogeninduced cracking hic. Another type of hydrogen corrosion, stress orientated hydrogen induced cracking sochic, is normally found in the base metal adjacent to the weld, where the stress point is highest due to the internal pressure of the. Also high strength structural steels which are welded are exposed to a certain hydrogen pickup which means a risk at fracture and blistering. Hydrogen induced cracking is a mechanical fracture caused by penetration and diffusion of atomic hydrogen into the internal structure of steel, which changes into molecular. Jun 03, 2018 hydrogeninduced cracking hic refers to the internal cracks brought about by material trapped in budding hydrogen atoms. A subset of the 1140 mpa aisi 4340 material also underwent plasma nitriding. Hydrogen induced stress cracking hisc is a commonly used expression in the offshore community when referring to he 6. Hydrogen embrittlement he also known as hydrogen assisted cracking hac and hydrogen induced cracking hic, describes the embrittling of metal after being exposed to hydrogen.
Hydrogen cracking may also be called cold cracking or delayed cracking. The charged tubes were submitted to tensile test and their susceptibility to hydrogen induced stress cracking hisc was assessed, as well as an examination of fracture surface. It is also called hydrogen assisted cracking hac and delayed cracking since it does not occur right after welding, but a few hours or days after the weld has completely cooled down to ambient temperature. Detection of hydrogen induced cracks during inservice. Jun 27, 2019 the brittle nature of the fracture surface, calcareous deposits on the ferrule and exposure to cathodic protection suggested hydrogen induced stress cracking hisc.
Hydrogen cracking is also named as toe cracking or underbead cracking due to its location of occurrence. Our hydrogen embrittlement testing labs can carry out hisc testing of nickel alloys and duplex stainless steels, widely used in subsea components, to. Hydrogeninduced craking hic, also referred to as hydrogen stress cracking or static fatigue, is a typical form of hydrogen embrittlement. Hydrogen induced stress cracking of swaged super duplex. Hydrogen induced plasticity in stress corrosion cracking of engineering systems article in engineering fracture mechanics 686. Journal of iron and steel research international 22. Sulfide stress cracking an overview sciencedirect topics.
This is a type of deterioration which can be linked to corrosion and corrosioncontrol processes. The path of crack growth in hydrogen embrittled steels is a function of the stress intensity factor, k mpavm. It can lead to unexpected sudden failure of normally ductile metal alloys subjected to a tensile stress, especially at elevated temperature. A corrosive medium especially chloridebearing or hydrogen sulphide h 2 s media. Efc publication 17, 2nd edition, corrosion resistant alloys for oil and gas production. Sohics occur predominately at welds and can be missed during an nde. Defects hydrogen cracks in steels identification twi.
It involves atomic hydrogen, which is the smallest atom, that diffuses into a metallic structure. Sulfide stress cracking mostly occurs in very highly acidic environments. Effect of microstructure on hydrogeninduced cracking of. Hydrogeninduced cracking hic refers to the internal cracks brought about by material trapped in budding hydrogen atoms. May 19, 2009 susceptibility to hydrogen blistering and hydrogen induced cracking can be apportioned to the quality of the steel plate used. Cracks can develop by both transgranular and intergranular paths.
Hydrogen induced cracking hic in steel is a risk problem when steels are charged with hydrogen in service as in various hydrogen sulfide environments like sour oil and gas wells and some power plants. Stressoriented hydrogeninduced cracking an overview. Hydrogen induced stress cracking of duplex stainless steel subsea components. Hydrogen embrittlement and stress corrosion cracking. Cracking occurs due to a significant loss in ductility. Hydrogeninduced cracking an overview sciencedirect topics. Stress corrosion cracking facts and how to reduce the risk. When metal is subjected to tensile stress with high level of hydrogen content, hydrogen induced cracking occurs. Such failures attributed to hydrogen induced stress cracking hisc are clearly not acceptable from the perspective of safety, environmental.