Skip Nav Destination
Close Modal
Search Results for
HK
Update search
Filter
- Title
- Authors
- Author Affiliations
- Full Text
- Abstract
- Keywords
- DOI
- ISBN
- EISBN
- Issue
- ISSN
- EISSN
- Volume
- References
Filter
- Title
- Authors
- Author Affiliations
- Full Text
- Abstract
- Keywords
- DOI
- ISBN
- EISBN
- Issue
- ISSN
- EISSN
- Volume
- References
Filter
- Title
- Authors
- Author Affiliations
- Full Text
- Abstract
- Keywords
- DOI
- ISBN
- EISBN
- Issue
- ISSN
- EISSN
- Volume
- References
Filter
- Title
- Authors
- Author Affiliations
- Full Text
- Abstract
- Keywords
- DOI
- ISBN
- EISBN
- Issue
- ISSN
- EISSN
- Volume
- References
Filter
- Title
- Authors
- Author Affiliations
- Full Text
- Abstract
- Keywords
- DOI
- ISBN
- EISBN
- Issue
- ISSN
- EISSN
- Volume
- References
Filter
- Title
- Authors
- Author Affiliations
- Full Text
- Abstract
- Keywords
- DOI
- ISBN
- EISBN
- Issue
- ISSN
- EISSN
- Volume
- References
NARROW
Format
Topics
Book Series
Date
Availability
1-20 of 41 Search Results for
HK
Follow your search
Access your saved searches in your account
Would you like to receive an alert when new items match your search?
Sort by
Image
in Radiographic Inspection for Creep Fissures in Reformer-Furnace Tubes
> ASM Failure Analysis Case Histories: Failure Modes and Mechanisms
Published: 01 June 2019
Fig. 1 Reformer-furnace cell from which cast tubes of ASTM A 297, HK-40, heat-resistant alloy were radiographically inspected for the detection of creep fissuring. (a) Schematic of furnace cell showing positions of radiographic sources and films. Dimensions given in inches. (b) Radiograph
More
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.steel.c9001714
EISBN: 978-1-62708-232-7
... Abstract In a HyL III heat exchanger's radiant pipes, metal dusting reduced the pipe thickness from 8.5 to 3 mm in just nine months, leaving craters on the inner surface. The pipes are fabricated from HK 40 alloy. The heated gas (400 to 800 deg C) consisted of CO, CO2, and H2, with a 4:1 CO/CO2...
Abstract
In a HyL III heat exchanger's radiant pipes, metal dusting reduced the pipe thickness from 8.5 to 3 mm in just nine months, leaving craters on the inner surface. The pipes are fabricated from HK 40 alloy. The heated gas (400 to 800 deg C) consisted of CO, CO2, and H2, with a 4:1 CO/CO2 ratio. Metallographic investigations revealed that the surface of the attacked pipes consisted of (Cr, Fe) carbide. The metal dusting was the result of a decomposition process (CO to CO2 + C) that deposited C on the pipe surface. Because of the high temperature, the C subsequently diffused through the surface oxide layer (Cr2O3), triggering a succession of reactions that led to pitting and the formation of craters.
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.chem.c9001735
EISBN: 978-1-62708-220-4
... Abstract A sample tube was removed from a reformer furnace for life assessment after 69,000 h of service. Sections were cut from the tube, which was a spindle cast A297 Grade HK 40 (25 Cr, 20 Ni, 0.4 C) austenitic steel of 122.5 mm OD and 10.5 mm nominal wall thickness. They were examined...
Abstract
A sample tube was removed from a reformer furnace for life assessment after 69,000 h of service. Sections were cut from the tube, which was a spindle cast A297 Grade HK 40 (25 Cr, 20 Ni, 0.4 C) austenitic steel of 122.5 mm OD and 10.5 mm nominal wall thickness. They were examined metallographically on transverse sections and on longitudinal sections through the butt welds joining the separate cast segments of the tube. Creep damage was mainly concentrated within the inner one third of the wall thickness. The use of damage assessment parameters in evaluating the reformer tube remaining life showed the welds to be inadequate, and to have a strength and creep resistance below those of the base metal.
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.modes.c0060144
EISBN: 978-1-62708-234-1
... filled with a nickel catalyst. The tubes were centrifugally cast from ASTM A297, grade HK-40 (Fe-25Cr-20Ni-0.40C), heat-resistant alloy. The tube was concluded after metallurgical inspection to have failed from creep rupture (i.e., stress rupture). A project for detecting midwall creep fissuring...
Abstract
Two steam-methane reformer furnaces were subjected to short-time heat excursions because of a power outage, which resulted in creep bulging in the Incoloy 800 outlet pigtails, requiring complete replacement. Each furnace had three cells, consisting of 112 vertical tubes per cell, each filled with a nickel catalyst. The tubes were centrifugally cast from ASTM A297, grade HK-40 (Fe-25Cr-20Ni-0.40C), heat-resistant alloy. The tube was concluded after metallurgical inspection to have failed from creep rupture (i.e., stress rupture). A project for detecting midwall creep fissuring was instigated as a result of the failure. It was concluded after laboratory radiography and macroexamination that if the fissure were large enough to show on a radiograph, either with or without the catalyst, the tube could be expected to fail within one year. The set up for in-service radiograph examination was described. The tubes of the furnace were radiographed during shut down and twenty-four tubes in the first furnace and 53 in the second furnace showed significant fissuring. Although, radiography was concluded to be a practical technique to provide advance information, it was limited to detecting fissures caused by third-stage creep in tubes because of the cost involved in removing the catalysts.
Series: ASM Failure Analysis Case Histories
Volume: 2
Publisher: ASM International
Published: 01 December 1993
DOI: 10.31399/asm.fach.v02.c9001280
EISBN: 978-1-62708-215-0
... Abstract An HK-40 alloy tubing weld in a reformer furnace of a petrochemical plant failed by leaking after a shorter time than that predicted by design specifications. Leaking occurred because of cracks that passed through the thickness of the weldment. Analysis of the cracked tubing indicated...
Abstract
An HK-40 alloy tubing weld in a reformer furnace of a petrochemical plant failed by leaking after a shorter time than that predicted by design specifications. Leaking occurred because of cracks that passed through the thickness of the weldment. Analysis of the cracked tubing indicated that the sulfur and phosphorus contents of the weld metal were higher than specified, the thickness was narrower at the weld, and the mechanical resistance of the weld metal was lower than specified. Cracking initiated at the weld root by coalescence of creep cavities. Propagation and expansion was aided by internal carburization. Quality control of welding procedures and filler metal was recommended.
Series: ASM Failure Analysis Case Histories
Volume: 1
Publisher: ASM International
Published: 01 December 1992
DOI: 10.31399/asm.fach.v01.c9001051
EISBN: 978-1-62708-214-3
... Knoop readings of 207, 271, and 270 HK respectively (where 207 HK ≅ 8.7 HRC and 274 HK ≅ 24 HRC), values consistent with an ASTM A302 grade B material. The epoxy mold for sample B was broken open and the specimen was heat treated as follows: A metallurgical furnace was stabilized at 540 °C...
Abstract
A pair of steam generators operating at a pressurized water reactor site were found to be leaking near a closure weld. The generators were the vertical U-tube type, constructed from ASTM A302 grade B steel. The shell material exhibited high hardness values prior to confirmatory heat treatment, indicating high residual stresses in the area of the weld. All cracks were transgranular and were associated with pits on the inside surfaces of the vessels. It was concluded that the cracking was caused by a low-cycle corrosion fatigue phenomenon, with cracks initiating at areas of localized corrosion and propagating by fatigue. The cause of the pitting/cracking was related to the unit's copper species in solution.
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.usage.c0046366
EISBN: 978-1-62708-236-5
... through one of the deep score marks in the aluminum alloy adapter revealed a large particle of chromium embedded in the groove ( Fig. 1c ). A hardness test performed on the particle indicated a hardness of 850 HK (66 HRC); the hardness of the aluminum alloy adjacent to the particle was 186 HK (86 HRB...
Abstract
Several large chromium-plated 4340 steel cylinders were removed from service because of deep longitudinal score marks in the plating. One of the damaged cylinders and a mating cast aluminum alloy B850-T5 bearing adapter that also exhibited deep longitudinal score marks were submitted for examination. Analysis (visual inspection, manual testing of the hardness and adherence of the chromium plating, 100x microscopic examination, and hardness testing) supported the conclusions that high localized loads on the cylinder had resulted in chipping of the chromium plating, particles of which became embedded in the aluminum alloy adapter. The sliding action of the adapter with embedded hard particles resulted in scoring of both the cylinder and the adapter. If the cylinder alone had been available for examination, it might have been concluded that the scoring had been caused by entrapped sand or debris from an external source. No recommendations were made.
Series: ASM Failure Analysis Case Histories
Volume: 2
Publisher: ASM International
Published: 01 December 1993
DOI: 10.31399/asm.fach.v02.c9001381
EISBN: 978-1-62708-215-0
... hardness of 421 HK (∼41 HRC). Transverse specimens had an average hardness of 441 HK (∼45 HRC). Conclusion and Recommendations Most Probable Cause It was initially suspected that hydrogen embrittlement caused crack initiation. It was concluded, however, that the failure was caused by a high...
Abstract
A helicopter main rotor bolt failed in the black-coated region between the threads and the taper section of the shank during assembly. The torque applied was approximately 100 N·m (900 in.·lbf) when the bolt sheared. No other bolts were reported to have failed. The failed bolt material conformed to AISI E4340 steel, as specified. The microstructure was tempered martensite, with hardness ranging from 41 to 45 HRC. Failure was in the shear ductile mode. The crack initiated in the area of slag inclusions. Inspection of other bolts from the same shipment was recommended.
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.chem.c9001687
EISBN: 978-1-62708-220-4
... properties. Grain boundary sliding and dislocation motion were enhanced, causing a local increase in the steady state strain rate and the premature failure of the tube. Grain boundary sliding Plastic deformation Spalling Voids HK UNS J94224 Creep fracture/stress rupture The petrochemical...
Abstract
Microstructural examinations on transverse cross sections of a steam reformer tube, showed the presence of large macrovoids elongated in the radial direction and emanating from the internal surface of the tube. The macrovoids were located at the interdendritic regions, and were partially filled by a Mn-Fe bearing chromium oxide film. The areas adjacent to the oxide film were chemically depleted in C, Cr and Mn and rich in Fe and Ni. Associated with this depletion were a large concentration of microvoids. It was suggested that the dissolution of carbides in areas surrounding the macrovoids and the concentration of stresses at their tips, caused extensive localized plastic deformation which led to the formation of microvoids and subsequently to the spalling of the oxide film. The non-protective character of the film induced a progressive deterioration of the grain boundaries properties. Grain boundary sliding and dislocation motion were enhanced, causing a local increase in the steady state strain rate and the premature failure of the tube.
Book Chapter
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.power.c0048777
EISBN: 978-1-62708-229-7
.... The microhardness of the dendritic layer was 489 to 591 HK and 47 to 52 HRC, while the HAZ was 179 to 258 HK and 85 HRB to 21 HRC. A qualitative microprobe analysis of the dendritic layer revealed that it contained over 1% C, higher than the carbon content of the base metal. This high hardness is consistent...
Abstract
A 150 cm ID boiler drum made form ASTM A515, grade 70, steel failed during final hydrotesting at a pressure of approximately 26 MPa. Brittle fractures were revealed in between two SA-106C nozzles and remainder was found to involve tearing. Short, flat segments of fracture area, indicative of pre-existing cracks, were revealed by examination of the fracture surface at the drain grooves arc gouged at the nozzle sites. A thin layer of material with a dendritic structure was observed at the groove surface. The dendritic layer was revealed by qualitative microprobe analysis to contain over 1% C, higher than the carbon content of the base metal. The cracks in the drain groove surface could have occurred after arc gouging, during subsequent stress-relieving, or during the hydrostatic test. Flame cutting is not recommended for the type of steel used in the boiler drum because it can lead to local embrittlement and stress raisers, potentially initiating major failures.
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.modes.c0048846
EISBN: 978-1-62708-234-1
... suggest that the ferrite bands served as initiation sites for the failure and that they lowered the rupture strength of the weld metal. The Knoop hardnesses of the bands tended to be in the range 138 to 144 HK, while the adjacent areas of the interbead HAZ were 161 to 168 HK. Qualitative analyses...
Abstract
A main steam pipe was found to be leaking due to a large circumferential crack in a pipe-to-fitting weld in one of two steam leads between the superheater outlet nozzles and the turbine stop valves (a line made of SA335-P22 material). The main crack surface was found to be rough, oriented about normal to the outside surface, and had a dark oxidized appearance. The cracking was found to be predominantly intergranular. Distinct shiny bands that etched slower than the remainder of the sample at the top of each individual weld bead were revealed by microscopic examination. These bands were found contain small cracks and microvoids. A mechanism of intergranular creep rupture at elevated temperature was identified as a result of a series of stress-rupture and tensile tests. It was revealed by the crack shape that cracking initiated on the pipe exterior, then propagated inward and in the circumferential direction in response to a bending moment load. It was concluded that the primary cause of failure was the occurrence of bending stresses that exceeded the stress levels predicted by design calculations and that were higher than the maximum allowable primary membrane stress.
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.modes.c9001671
EISBN: 978-1-62708-234-1
... structure with a relative hardness of 790 HK (25gf load). This sub-layer has an apparent unresolved substructure after etching. A second layer, which is occasionally reported, is a lower carbon containing austenitic layer with a hardness of 403 HK which lacks any evidence of being influenced by etching...
Abstract
Important clues about the probable cause of a gun tube explosion were obtained from a fractographic and metallographic examination of the fragments. The size, distribution, and surface markings of fragments may be used to localize the explosion and deduce its intensity. Microstructural features such as voids, adiabatic shear, and structural surface alterations also indicate the explosion intensity and further allow a comparison of the tube structure near and away from the explosion zone. These, and other metallurgical characteristics, are illustrated and discussed for cases of accidental and deliberately caused explosions of large caliber gun tubes.
Series: ASM Failure Analysis Case Histories
Volume: 2
Publisher: ASM International
Published: 01 December 1993
DOI: 10.31399/asm.fach.v02.c9001267
EISBN: 978-1-62708-215-0
... an average Knoop hardness of 617 HK, which corresponds to 54 HRC—well below the properties specified for 0.76 mm (0.030 in.) wire ( Fig. 9 ). However, microhardness measurements obtained with the diamond pyramid indentation oriented transverse to the wire axis showed an average of 815 HK or 63.5 HRC, which...
Abstract
Music wire springs used in a printer return mechanism failed near the bend in the hook portion of the spring during qualification testing. Samples were examined in a scanning electron microscope equipped with an energy-dispersive x-ray microprobe. Fatigue fractures originated at rub marks on the inside edge of the spring. An investigation of loads encountered in service indicated that the springs had been loaded to a large fraction of the yield strength. Redesign of the spring mechanism was recommended.
Series: ASM Failure Analysis Case Histories
Volume: 1
Publisher: ASM International
Published: 01 December 1992
DOI: 10.31399/asm.fach.v01.c9001065
EISBN: 978-1-62708-214-3
...) hardness measurements were performed on the cross section of one of the sections removed. Average hardness values (500 gf load) were as follows: pipe, 159 HK; HAZ (pipe side), 176 HK; weld, 197 HK; HAZ (elbow side), 179 HK, elbow, 170 HK. All of the values were consistent with those expected...
Abstract
A 460 mm (18 in.) diam suction line to the main feed water pump for a nuclear power plant failed in a violent, catastrophic manner. Samples of pipe, elbow, and weld materials (ASTM A106 grade B carbon steel, ASTM A234 grade WPB carbon steel, and E7018 carbon steel electrode, respectively) from the suction line were analyzed. Evidence of overall thinning of the elbow and pipe material and ductile tearing of fractures indicated that the feed water pipe failed as a result of an erosion corrosion mechanism, which thinned the wall sufficiently to cause rapid, ductile tearing of the material after its design stress had been exceeded. It was recommended that steel with a higher chromium content be used to mitigate the erosion corrosion potential in the lines and that more rigorous nondestructive (ultrasonic) examinations be performed.
Book Chapter
Series: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.mech.c0090994
EISBN: 978-1-62708-225-9
... shot peened. The microhardness of the wire averaged 591 Knoop (HK 500 ). This equates to an approximate ultimate tensile strength slightly higher than the specified range. Conclusions The springs failed during installation due to the presence of preexisting defects. The crack surfaces were...
Abstract
Two large tension springs fractured during installation. The springs were manufactured from a grade 9254 chromium-silicon steel spring wire. The associated material specification allows wire in the cold-drawn or oil-tempered (quenched-and-tempered) condition. The specified wire tensile strength range was 1689 to 1793 MPa (245 to 260 ksi). The finished springs were to be shot peened for greater fatigue resistance. Investigation (visual inspection, 3x images, 2% nital etched 148x SEM images, chemical analysis, hardness testing, and EDS analysis) supported the conclusion that the springs failed during installation due to the presence of preexisting defects. Crack surfaces were found to be corroded and phosphate coated, indicating that the cracks occurred during manufacture. Installation, which presumably entailed some axial extension, resulted in ductile overload failure at the crack sites. Recommendations included evaluating the manufacturing steps to identify the process(es) wherein the cracking was likely occurring. It was further recommended that a suitable nondestructive method such as magnetic particle inspection be implemented.
Series: ASM Failure Analysis Case Histories
Volume: 2
Publisher: ASM International
Published: 01 December 1993
DOI: 10.31399/asm.fach.v02.c9001329
EISBN: 978-1-62708-215-0
... halogens. Mechanical Properties Hardness Microhardness (Knoop) testing (200 g load) yielded the following average values for the elbow and two valve bodies, respectively: 135, 148, and 163 HK (casting material); 85, 79, and 59 HK (dealloyed areas). Obviously, the microhardness values...
Abstract
Various aluminum bronze valves and fittings on the essential cooling water system at a nuclear plant were found to be leaking. The leakage was limited to small-bore socket-welded components. Four specimens were examined: three castings (an ASME SB-148 CA 952 elbow from a small-bore fitting and two ASME SB-148 CA 954 valve bodies) and an entire valve assembly. The leaks were found to be in the socket-weld crevice area and had resulted from dealloying. It was recommended that the weld joint geometry be modified.
Series: ASM Failure Analysis Case Histories
Volume: 1
Publisher: ASM International
Published: 01 December 1992
DOI: 10.31399/asm.fach.v01.c9001030
EISBN: 978-1-62708-214-3
... indentations. The unaffected base metal hardness was an acceptable 493 HK (48 HRC). The brittle martensite layer was 852 HK (66 HRC). Stress Analysis Analytical Analysis of a typical interference-fit fastener application with 0.08 mm (0.003 in.) average interference shows that radial stresses...
Abstract
Cracks were discovered between interference-fit fasteners (MoS2-coated Ti-6Al-4V) that had been incorporated into a fighter aircraft primary structural frame (D6ac steel) to enhance structural fatigue life. Examination of sections cut from the cracked frame established that the cracks propagated by stress-corrosion cracking. The cause of cracking was twofold: use of interference-fit fasteners exposed to moisture intrusion from a marine environment and poor hole quality. Failure was intensified by dissimilar-metal contact in the presence of weak acidic electrolyte (dissociated MoS2). Control of machining parameters to prevent formation of brittle martensite, use of galvanically compatible fasteners, and use of an alternate lubricant were recommended.
Series: ASM Failure Analysis Case Histories
Volume: 3
Publisher: ASM International
Published: 01 December 2019
DOI: 10.31399/asm.fach.v03.c9001823
EISBN: 978-1-62708-241-9
... Table 2 for results of the testing. The hardness in the white portion of Mount A (Region 1) was ~800 HK, which is consistent with the high hardness of eutectic iron. Region 1 must have been carburized from the coating or hydrocarbon product. The hardness in Region 2 (hardness locations B and C) ranged...
Abstract
A section of pipe in a hydrocarbon pipeline was found to be leaking. The pipeline was installed several decades earlier and was protected by an external coating of extruded polyethylene and a cathodic protection system. The failed pipe section was made from API 5L X46 line pipe steel, approximately 22 cm (8.7 in.) OD x 0.5 cm (0.2 in.) wall thickness, which was electric resistance welded along the longitudinal seam. The pressure at the time and location of the failure was 2760 kPa, which corresponds to 20% of the specified minimum yield strength. The cause of failure (based on visual inspection, magnetic particle inspection, stereoscopic analysis, scanning electron microscopy, tensile and hardness testing, and chemical analysis) was attributed to damage resulting from a lightning strike.
Series: ASM Failure Analysis Case Histories
Volume: 2
Publisher: ASM International
Published: 01 December 1993
DOI: 10.31399/asm.fach.v02.c9001327
EISBN: 978-1-62708-215-0
... Microhardness (Knoop) measurements were performed on the base metal, weld, and HAZ of the large end of the reducer. Average values of 184, 211, and 199 HK, respectively, were obtained—typical for SA-106 grade B material. Tensile Properties Tensile testing yielded the following results: yield strength...
Series: ASM Failure Analysis Case Histories
Volume: 1
Publisher: ASM International
Published: 01 December 1992
DOI: 10.31399/asm.fach.v01.c9001118
EISBN: 978-1-62708-214-3
... the major factor contributing to the fatigue failures. Microhardness measurements obtained on the cross section of spring 1 (100 g load) Table 1 Microhardness measurements obtained on the cross section of spring 1 (100 g load) Length, m Hardness HK HRC 46.0 672 57.0 46.5 658...
Abstract
Failure of AISI type 321 stainless steel internal springs from newly manufactured lip seals on a shaft between a turbine power unit and a pump in a commercial aircraft secondary unit was investigated. Examination of the coils from two failed springs showed that both had failed by fatigue. The springs contained drawing defects that served as the fatigue crack initiation sites. It was recommended that the wire drawing process be investigated for various levels of steel cleanliness to predict the incidence of drawing defects at the wire surface. Stress analysis to determine the minimum tolerable defect size was also recommended.