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Book Chapter
Failure of Trailer Kingpins Caused by Overheating During Forging
Available to PurchaseSeries: ASM Failure Analysis Case Histories
Volume: 2
Publisher: ASM International
Published: 01 December 1993
DOI: 10.31399/asm.fach.v02.c9001302
EISBN: 978-1-62708-215-0
..., especially with respect to the accuracy of the optical pyrometer temperature readout. Also, procedures must be developed such that forging blanks that trigger the over-temperature alarm are reliably and permanently removed from the production line. Crack propagation Forging defects Mechanical...
Abstract
To forged AISI 4140 steel trailer kingpins fractured after 4 to 6 months of service. Fractographic and metallographic examination revealed that cracks were present in the spool-flange shoulder region of the defective kingpins prior to installation on the trailers. The cracks grew and coalesced during service. Consideration of the manufacturing process suggested that the cracks were the result of overheating of the kingpin blanks prior to forging, which was exacerbated during forging by deformation heating in the highly-strained region. This view was supported by results of two types of tensile tests conducted near the incipient melting temperature at the grain boundaries. All kingpins made by the supplier of the fractured ones were ultrasonically inspected and six more anticipated to fail were found. It was recommended that the heating of forging blanks be more carefully controlled, especially with respect to the accuracy of the optical pyrometer temperature readout. Also, procedures must be developed such that forging blanks that trigger the over-temperature alarm are reliably and permanently removed from the production line.
Book Chapter
Fatigue Cracking of Headers for Superheated Water Because of Notches at Welds
Available to PurchaseSeries: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.process.c0089734
EISBN: 978-1-62708-235-8
... welds on the surfaces of the flanges. Recommendations included using ultrasonic testing to identify the appropriate joints and then replacing them. Special attention to accuracy of fit-up in the replacement joints was also recommended to achieve smooth, notch-free contours on the interior surfaces...
Abstract
A system of carbon steel headers, handling superheated water of 188 deg C (370 deg F) at 2 MPa (300 psi) for automobile-tire curing presses, developed a number of leaks within about four months after two to three years of leak-free service. All the leaks were in shielded metal arc butt welds joining 200 mm (8 in.) diam 90 deg elbows and pipe to 200 mm (8 in.) diam welding-neck flanges. A flange-elbow-flange assembly and a flange-pipe assembly that had leaked were removed for examination. Investigation (visual inspection, hardness testing, chemical analysis, magnetic-particle testing, radiographic inspection, and 2% nital etched 1.7x views) showed varying IDs on the assemblies and supported the conclusions that the failures of the butt welds were the result of fatigue cracks caused by cyclic thermal stresses that initiated at stress-concentrating notches at the toes of the interior fillet welds on the surfaces of the flanges. Recommendations included using ultrasonic testing to identify the appropriate joints and then replacing them. Special attention to accuracy of fit-up in the replacement joints was also recommended to achieve smooth, notch-free contours on the interior surfaces.
Book Chapter
Fatigue Failure of Extrusion Dies: Effect of Process Parameters and Design Features on Die Life
Available to PurchaseSeries: ASM Failure Analysis Case Histories
Volume: 3
Publisher: ASM International
Published: 01 December 2019
DOI: 10.31399/asm.fach.v03.c9001788
EISBN: 978-1-62708-241-9
... the determination of existing load conditions in the potential fatigue location of the die, reliable fatigue data at required process conditions, and the accuracy and reliability of numerical values obtained from simulation [ 6 ]. Damage Parameters Used The fundamental problem in reducing multi-axial loading...
Abstract
Several failed dies were analyzed and the results were used to evaluate fatigue damage models that have been developed to predict die life and aid in design and process optimization. The dies used in the investigation were made of H13 steels and fractured during the hot extrusion of Al-6063 billet material. They were examined to identify critical fatigue failure locations, determine corresponding stresses and strains, and uncover correlations with process parameters, design features, and life cycle data. The fatigue damage models are based on Morrow’s stress and strain-life models for flat extrusion die and account for bearing length, fillet radius, temperature, and strain rate. They were shown to provide useful information for the analysis and prevention of die failures.
Book Chapter
Nondestructive Evaluation Applications for Failure Analysis
Available to PurchaseSeries: ASM Handbook
Volume: 11
Publisher: ASM International
Published: 15 January 2021
DOI: 10.31399/asm.hb.v11.a0006758
EISBN: 978-1-62708-295-2
... or chemicals, contact with the part, moving the part, heating or cooling the part, mechanically exciting the part, or irradiating the part. If available, material- and part-specific calibration standards can aid in the accuracy of the NDE efforts. It is also advisable for the customer to ensure NDE personnel...
Abstract
The goal of using nondestructive evaluation (NDE) in conjunction with failure analysis is to obtain the most comprehensive set of data in order to characterize the details of the damage and determine the factors that allowed the damage to occur. The NDE results can be used to determine optimal areas upon which to focus for sectioning and metallography in order to further investigate the condition of the component. This article provides information on the inspection method available for failure analysis, including standard methods such as visual testing, penetrant testing, and magnetic particle testing. It covers the effects of various factors on the properties of the part that may impact failure analysis, describes the characterization of damage modes and crack sizes, and finally discusses the processes involved in application of NDE results to failure analysis.
Book Chapter
X-Ray Spectroscopy in Failure Analysis
Available to PurchaseSeries: ASM Handbook
Volume: 11
Publisher: ASM International
Published: 15 January 2021
DOI: 10.31399/asm.hb.v11.a0006770
EISBN: 978-1-62708-295-2
... for failure analysis, qualitative results are adequate, but the method can determine quantitative elemental compositions to a precision of 0.01 wt% with relative accuracies of ±5%, depending on the specific material, type of x-ray detector used, the method of data analysis employed, and, as always, the skill...
Abstract
X-ray spectroscopy is generally accepted as the most useful ancillary technique that can be added to any scanning electron microscope (SEM), even to the point of being considered a necessity by most operators. While “stand-alone” x-ray detection systems are used less frequently in failure analysis than the more exact instrumentation employed in SEMs, the technology is advancing and is worthy of note due to its capability for nondestructive analysis and application in the field. This article begins with information on the basis of the x-ray signal. This is followed by information on the operating principles and applications of detectors for x-ray spectroscopy, namely energy-dispersive spectrometers, wavelength-dispersive spectrometers, and handheld x-ray fluorescence systems. The processes involved in x-ray analysis in the SEM and handheld x-ray fluorescence analysis are then covered. The article ends with a discussion on the applications of x-ray spectroscopy in failure analysis.
Book Chapter
Distortion Failure of an Automotive Valve Spring
Available to PurchaseSeries: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.modes.c0092131
EISBN: 978-1-62708-234-1
... had 10% lower yield strength than material in the undeformed spring. The estimates of yield strength were considered valid because of two factors: the accuracy of the hardness testing and characteristically consistent ratios of yield strength to tensile strength for the grades of steel commonly used...
Abstract
The engine of an automobile lost power and compression and emitted an uneven exhaust sound after several thousand miles of operation. When the engine was dismantled, it was found that the outer spring on one of the exhaust valves was too short to function properly. The short steel spring and an outer spring (both of patented and drawn high-carbon steel wire) taken from another cylinder in the same engine were examined in the laboratory to determine why one had distorted and the other had not. Investigation (visual inspection, microstructure examination, and hardness testing) supported the conclusion that the engine malfunctioned because one of the exhaust-valve springs had taken a 25% set in service. Relaxation in the spring material occurred because of the combined effect of improper microstructure (proeutectoid ferrite) plus a relatively high operating temperature. Recommendations included using quenched-and-tempered steel instead of patented and cold-drawn steel or using a more expensive chromium-vanadium alloy steel instead of plain carbon steel; the chromium-vanadium steel would also need to be quenched and tempered.
Series: ASM Handbook
Volume: 11
Publisher: ASM International
Published: 15 January 2021
DOI: 10.31399/asm.hb.v11.a0006772
EISBN: 978-1-62708-295-2
... sUAS-generated point cloud data are generally not as accurate. Without the use of additional surveying tools such as ground control points (GCPs), sUAS-generated data can be accurate to within ±15 cm (6 in.). The GCPs can increase the accuracy of sUAS point cloud data to within ±3 cm (1.2...
Abstract
Failure analysis is generally defined as the investigation and analysis of parts or structures that have failed or appeared to have failed to perform their intended duty. Methods of field inspection and initial examination are also critical factors for both reconstruction analysts and materials failure analysts. This article focuses on the general methods and approaches from the perspective of a reconstruction analyst. It describes the elements of accident reconstruction, which have conceptual similarity with the principles for failure analysis of material incidents that are less complex than a large-scale accident. The approach presented is that the analysis and reconstruction is based on the physical evidence. The article provides a brief review of some general concepts on the use and limitations of advanced data acquisition tools and computer modeling. Legal implications of destructive testing are discussed in detail.
Book Chapter
Failure Analysis of a Cam–Follower System Affected by a Crack
Available to PurchaseSeries: ASM Failure Analysis Case Histories
Volume: 3
Publisher: ASM International
Published: 01 December 2019
DOI: 10.31399/asm.fach.v03.c9001797
EISBN: 978-1-62708-241-9
.... , Su H. : Minimizing and restricting vibrations in high-speed cam-follower system over a range of speeds . J. Mech. Des. Trans. ASME 74 , 1157 – 1164 ( 2007 ) 10.1115/1.2723812 6. Rothbart H.A. : Design, dynamic and accuracy . Wiley , New York ( 1956 ) 7. Kim H.R...
Abstract
Cam crack failures are a common occurrence in cam-follower systems often caused by excessive loading or inappropriate operating conditions. An investigation into such a failure was conducted to assess the effect of cam crack damage on the dynamic behavior of cam-follower systems. It was shown both theoretically and experimentally that a cracked cam causes an overall reduction in stiffness. To further probe the effect, investigators derived an analytical formula expressing the time varying stiffness of a cam-follower system. They also succeeded in quantifying the relationship between crack size and stiffness, showing that cracks have an amplitude modulating effect.
Book Chapter
Optical Testing and Characterization
Available to PurchaseSeries: ASM Handbook
Volume: 11B
Publisher: ASM International
Published: 15 May 2022
DOI: 10.31399/asm.hb.v11B.a0006937
EISBN: 978-1-62708-395-9
... such as density differences, fillers, pigments, and voids. With the described setup, accuracies of 0.1 to 0.3% can be obtained. However, if haze is greater than 30%, ASTM E 167 should be used. Transmission is normally measured and plotted against wavelength. If a material exhibits no internal absorption...
Abstract
Optical testing of plastics includes the characterization of materials and the analysis of optical components. If a material is tested for transmission, haze, yellowness, and refractive index, the knowledge of its optical properties is nearly complete. For optical components, surface irregularity, birefringence, and internal contamination must also be considered. These characteristics are a function of the material and the fabrication method. Gloss and color also are affected by the base material and measured as optical properties.
Book Chapter
An Investigation of the Development of Defects During Flow Forming of High Strength Thin Wall Steel Tubes
Available to PurchaseSeries: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.process.c9001601
EISBN: 978-1-62708-235-8
... A 370 ( Fig. 3 ). The specified and achieved mechanical properties and dimensional accuracies are presented in Table 2 . Flow forming sequence with thickness and hardness variations in each pass Table 1 Flow forming sequence with thickness and hardness variations in each pass Pass...
Abstract
Flow forming technology has emerged as a promising, economical metal forming technology due to its ability to provide high strength, high precision, thin walled tubes with excellent surface finish. This paper presents experimental observations of defects developed during flow forming of high strength SAE 4130 steel tubes. The major defects observed are fish scaling, premature burst, diametral growth, microcracks, and macrocracks. This paper analyzes the defects and arrives at the causative factors contributing to the various failure modes.
Book Chapter
Failure of a Laminated-Paper Food Cooking Tray
Available to PurchaseSeries: ASM Failure Analysis Case Histories
Volume: 2
Publisher: ASM International
Published: 01 December 1993
DOI: 10.31399/asm.fach.v02.c9001274
EISBN: 978-1-62708-215-0
..., the time required for the water to begin boiling was recorded for each cup position. The experiment was repeated four times for each of the three ovens. All test results were within experimental accuracy. To measure and verify the cooking temperatures of microwaveable dinners, sheathed-thermocouple...
Abstract
A laminated-paper microwave food tray collapsed with hot food in it. Microscopic examination of the failed tray revealed no structural or material defects. Five additional trays of like construction were also tested to determine the conditions necessary to simulate the permanent deflection of the tray handles that had occurred in the failed tray. Full distortion of the handles was obtained experimentally only by dropping a full hot tray on its end onto the floor. The test results indicated that the tray had slipped from the hand of the user.
Book Chapter
Mechanical Testing in Failure Analysis
Available to PurchaseSeries: ASM Handbook
Volume: 11
Publisher: ASM International
Published: 15 January 2021
DOI: 10.31399/asm.hb.v11.a0006761
EISBN: 978-1-62708-295-2
... of the appropriate hardness test, especially for bulk hardness; accuracy of hardness data; and so on. Hardness is usually used as a correlation to heat treatment condition and/or tensile strength. Therefore, any singular failure of a hardness test indicates an area that does not satisfy a tensile strength...
Abstract
Mechanical testing is an evaluative tool used by the failure analyst to collect data regarding the macro- and micromechanical properties of the materials being examined. This article provides information on a few important considerations regarding mechanical testing that the failure analyst must keep in mind. These considerations include the test location and orientation, the use of raw material certifications, the certifications potentially not representing the hardware, and the determination of valid test results. The article introduces the concepts of various mechanical testing techniques and discusses the advantages and limitations of each technique when used in failure analysis. The focus is on various types of static load testing, hardness testing, and impact testing. The testing types covered include uniaxial tension testing, uniaxial compression testing, bend testing, hardness testing, macroindentation hardness, microindentation hardness, and the impact toughness test.
Book Chapter
Modeling and Accident Reconstruction
Available to PurchaseSeries: ASM Handbook Archive
Volume: 11
Publisher: ASM International
Published: 01 January 2002
DOI: 10.31399/asm.hb.v11.a0003523
EISBN: 978-1-62708-180-1
... testing, the assumptions made for the model should be well known and the model should be proven. If the model is being used in combination with testing, then the accuracy of the model is not as critical, because proper testing should determine the validity of the model. Whether modeling, testing...
Abstract
This article focuses on the general methods and approaches from the perspective of a reconstruction analyst and includes discussions relevant to materials failure analysts at the incident scene. The elements of accident reconstruction are described. These have conceptual similarity with the principles for failure analysis of material incidents that are less complex than a large-scale accident. The article provides a brief review of some general concepts on the use of modeling which can be a very powerful tool for information pertaining to the reconstruction of an accident where the model can be a physical, mathematical, or logical representation of a physical system or process.
Book Chapter
Failure of a High-Speed Steel Twistdrill
Available to PurchaseSeries: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.machtools.c0089429
EISBN: 978-1-62708-223-5
... rating being “slight to medium.” A “medium” rating was permitted. Heat treatment and nitriding practices were consistent with those published by ASM International. After heat treatment, the drills were within the specified range of 64 to 66 HRC. Some twenty other inspections for dimensional accuracy...
Abstract
The failure of a high speed steel twist drill which caused injury to the user was investigated thoroughly to settle a legal suit. The drill was being used to remove a stud that broke in the vertical wall of a metalworking machine (upsetter) after drilling a pilot hole. The drill had shattered suddenly with a bang which caused a chip to be dislodged and cause the injury. A large nonmetallic inclusion parallel to the axis near the center of the drill was revealed in an unetched longitudinal section. Carbide bands in a martensitic matrix were indicated in an etched sample. It was concluded by the plaintiff's metallurgist that the failed drill was defective as the steel contained nonmetallic inclusions and carbide segregation which made it brittle. It was revealed by the defendant that the twist drill met all specifications of M1 high-speed steel and investigated several other drills without failure to prove that the failure was caused by use in excessive conditions. It was revealed by examination that the point of the broken drill was not the original point put on at manufacture but came from regrinding. Both technical and legal details have been discussed.
Book Chapter
X-Ray Diffraction Residual-Stress Measurement in Failure Analysis
Available to PurchaseSeries: ASM Handbook
Volume: 11
Publisher: ASM International
Published: 15 January 2021
DOI: 10.31399/asm.hb.v11.a0006768
EISBN: 978-1-62708-295-2
... ( Ref 13 ). The importance of the XRD method resides in its ability to measure residual and applied stress with high spatial resolution, speed, and excellent accuracy, and, in many cases, measurements can be performed nondestructively ( Ref 14 ). The measurement of residual stress via XRD is generally...
Abstract
X-ray diffraction (XRD) residual-stress analysis is an essential tool for failure analysis. This article focuses primarily on what the analyst should know about applying XRD residual-stress measurement techniques to failure analysis. Discussions are extended to the description of ways in which XRD can be applied to the characterization of residual stresses in a component or assembly and to the subsequent evaluation of corrective actions that alter the residual-stress state of a component for the purposes of preventing, minimizing, or eradicating the contribution of residual stress to premature failures. The article presents a practical approach to sample selection and specimen preparation, measurement location selection, and measurement depth selection; measurement validation is outlined as well. A number of case studies and examples are cited. The article also briefly summarizes the theory of XRD analysis and describes advances in equipment capability.
Book Chapter
Data Review, Conclusions, and Report Preparation
Available to PurchaseSeries: ASM Handbook
Volume: 11
Publisher: ASM International
Published: 15 January 2021
DOI: 10.31399/asm.hb.v11.a0006762
EISBN: 978-1-62708-295-2
... should be described textually. If multiple equations are used, each should be numbered sequentially for reference. Testing and data accuracy should be addressed. The appropriate appendix should be referenced concerning error analysis and computational and analytical details. The discussion section...
Abstract
As a failure investigation progresses, the time arrives when the data and results of the various testing and analyses are compiled, compared, and interpreted. Data interpretation should be relatively straightforward for results that align well. However, interpretation can be challenging when results from various tests seem contradictory or inconclusive. Regardless, conclusions must eventually be drawn from the data. This article discusses the processes involved in reviewing data, formulating conclusions, failure analysis report preparation and writing, and providing recommendations and follow-up with appropriate personnel to prevent future failures.
Book Chapter
X-Ray Diffraction Residual Stress Measurement in Failure Analysis
Available to PurchaseSeries: ASM Handbook Archive
Volume: 11
Publisher: ASM International
Published: 01 January 2002
DOI: 10.31399/asm.hb.v11.a0003528
EISBN: 978-1-62708-180-1
... resolution, speed, and excellent accuracy, and, in many cases, measurements can be performed nondestructively ( Ref 13 ). The measurement of residual stress via XRD is generally limited to polycrystalline materials ( Ref 6 ), that is, in materials with a grain structure (long-range ordering) as normally...
Abstract
This article focuses primarily on what an analyst should know about applying X-ray diffraction (XRD) residual stress measurement techniques to failure analysis. Discussions are extended to the description of ways in which XRD can be applied to the characterization of residual stresses in a component or assembly. The article describes the steps required to calibrate instrumentation and to validate stress measurement results. It presents a practical approach to sample selection and specimen preparation, measurement location selection, and measurement depth selection, as well as an outline on measurement validation. The article also provides information on stress-corrosion cracking and corrosion fatigue. The importance of residual stress in fatigue is described with examples. The article explains the effects of heat treatment and manufacturing processes on residual stress. It concludes with a section on the XRD stress measurements in multiphase materials and composites and in locations of stress concentration.
Series: ASM Handbook Archive
Volume: 11
Publisher: ASM International
Published: 01 January 2002
DOI: 10.31399/asm.hb.v11.a0003529
EISBN: 978-1-62708-180-1
... Before the details of the analytical method are discussed, it should be noted that there are few analytical methods that can be properly performed without knowledge of the intended composition. Most of the analytical methods in use today are instrumental methods whose accuracy depends on calibrations...
Abstract
This article describes some of the common elemental composition analysis methods and explains the concept of referee and economy test methods in failure analysis. It discusses different types of microchemical analyses, including backscattered electron imaging, energy-dispersive spectrometry, and wavelength-dispersive spectrometry. The article concludes with information on specimen handling.
Book Chapter
Hydrogen-Assisted Stress Cracking of Carburized and Zinc Plated SAE Grade 8 Wheel Studs
Available to PurchaseSeries: ASM Failure Analysis Case Histories
Volume: 2
Publisher: ASM International
Published: 01 December 1993
DOI: 10.31399/asm.fach.v02.c9001383
EISBN: 978-1-62708-215-0
... deflection rate of 10 −2 min. Machined samples with smooth gage lengths were also tested at two different deflection rates, 10 −2 min. and 10 −5 min. The slower strain rate tests showed a small drop in strength, but the statistical accuracy was not sufficient to state unequivocally that residual hydrogen...
Abstract
Several case-hardened and zinc-plated carbon-manganese steel wheel studs fractured in a brittle manner after very limited service life. The fracture surfaces of both front and rear studs showed no sign of fatigue beach marks or deformation in the form of shear lips that would indicate either a fatigue mechanism or ductile overload failure. SEM analysis revealed that the mode of fracture was intergranular decohesion, which indicates an environmental influence in the fracture mechanism. The primary fracture initiated at a thread root and propagated by environmentally-assisted slow crack growth until final fracture. The natural stress concentration at the thread root, when tightened to the required clamp load concomitant with the presence of cracks in the carburized case, was sufficient to exceed the critical stress intensity for hydrogen-assisted stress cracking (HASC). The zinc plating exacerbated the situation by providing a strong local corrosion cell in the form of a sacrificial anode region adjacent to the cracked thread. The enhanced generation of hydrogen in a corrosive environment subsequently lead to HASC of the wheel studs.
Book Chapter
Metal Waves or Laking on Zinc-Based Diecastings
Available to PurchaseSeries: ASM Failure Analysis Case Histories
Publisher: ASM International
Published: 01 June 2019
DOI: 10.31399/asm.fach.process.c9001199
EISBN: 978-1-62708-235-8
... was on an E. M. B. 12 B machine, using a ram velocity during cavity fill of approximately 0.76 m/sec and a piston pressure of 0.5 MPa. The cavity fill time varied between 11 and 19 milliseconds. Because of limitation in the accuracy of the data collected, the coefficient of discharge into the cavity 1 , 10...
Abstract
Lakes in zinc die castings are areas encompassed by irregular lines or waves on flat or slightly contoured surfaces which are intended to look uniform. The laked areas have to be removed by polishing before the castings can be plated. This adds considerably to the overall cost of production. Castings examined were of an automobile name-plate holder with two flat sides of approximately 113 sq cm. All castings produced during a trial showed laking defects, the number and position varying from casting to casting. It was found that formation of metal waves and lakes depended primarily on the design of the gate and runner system and operating conditions. High flow efficiencies, with adequate feeding to all sections of the die, and short cavity fill times are desirable.
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