Hardness testing with a portable hardness testing instrument also may be performed during on-site failure analysis Several different types of testers are available and in general are either electronic or mechanical in principle. Obviously small size and light weight are advantages in portable testers The major components of the portable laboratory may include A custom-made machine, plus auxiliary materials, for grinding and polishing small, mounted or unmounted metal A right-angle head, electric drill motor with attachments and materials for grinding and polishing selected spots on large parts or assemblies. It is also used for driving the grinding and polishing machine described in the previous item a portable microscope, with camera attachment and film for use in photographing metallographic specimens Equipment and materials for mounting and etching specimens a handheld single-lens reflex 35-mm camera, with macrolenses and film a pocket-size magnifier, and a ruler or scale A hacksaw and blades for cutting specimens Portable hardness tester Acetate tape, acetone, and containers RTV rubber for replicas Service History. The availability of a complete service history depends on how detailed and thorough the record keeping was prior to the failure. a complete service record greatly simplifies the assignment of the failure analyst. In collecting service histories, special attention should be given to environmental details such as normal and abnormal loading. accidental overloads, cyclic loads, temperature variations, temperature gradients, and operation in a corrosive environment. In most instances, however, complete service records are not available, forcing the analyst to work from fragmentary service information. When service data are sparse, the analyst must, to the best of his or her ability, deduce the service conditions. Much depends on the analyst's skill and judgment, because a misleading deduction can be more harmful than the absence of information Photographic Records. Photographs of the failed component or structure are oftentimes critical to an accurate analysis. A detail that appears almost inconsequential in a preliminary investigation may later be found to have serious consequences thus, a complete, detailed photographic record of the scene and failed component can be essential Photographs should be of professional quality, but this is not always possible. For the analyst who does his own photography, a single-lens reflex 35-mm or larger camera with a macrolens, extension bellows, and battery-flash unit is capable of producing excellent results. It may be desirable to supplement the 35-mm equipment with an instant camera and close-up lenses. Techniques and lighting are discussed in more detail in the article"Photography in Failure Analysis in this volume When accurate color rendition is required, the subject should be photographed with a color chart, which should be sent to the photographic studio for use as a guide in developing and printing. Some indication of size, such as a scale, coin, hand and so forth, should be included in the photograph Samples should be selected judiciously before starting the examination, especially if the investigation is to be lengthy or involved. As with photographs, the analyst is responsible for ensuring that the samples will be suitable for the intended purpose and that they adequately represent the characteristics of the failure. It is advisable to look for additional evidenc of damage beyond that which is immediately apparent. For failures involving large structures or key machinery, there is often a financially urgent need to remove the damaged structure or repair the machine to return to production. This is a valid reason to move evidence, but a reasonable attempt must be made to allow other parties, who may become involved in a potential legal case, to inspect the site. All concerned parties then can agree on the critical samples and the best way to remove them. If all parties are not available, care must be taken not to damage or alter critical elements to avoid spoiling evidence Guidelines governing sample collection are covered in ASTM E 620, E860, E 1020, and especially E 678. It is also recommended that samples be taken from other parts of the failed equipment as they may display supportive damage It is often necessary to compare failed components with similar components that did not fail to determine whether the failure was brought about by service conditions or was the result of an error in manufacture. For example, if a boiler tube fails and overheating is suspected to be the cause, and if investigation reveals a spheroidized structure in the boiler tube at the failure site (which may be indicative of overheating in service), then comparison with an unexposed tube will determine if the tubes were supplied in the spheroidized condition As another example, in the case of a bolt failure it is desirable to examine the nuts and other associated parts that may have contributed to the failures. Also, in failures involving corrosion, stress-corrosion, or corrosion fatigue, a sample of the fluid that has been in contact with the metal, or of any deposits that have formed, will often be required for analysis Abnormal Conditions and Wreckage Analysis. In addition to developing a history of the failed part it is also advisable to determine if any abnormal conditions prevailed. Determine also whether events-such as an accident--occurred inHardness testing with a portable hardness testing instrument also may be performed during on-site failure analysis. Several different types of testers are available and in general are either electronic or mechanical in principle. Obviously, small size and light weight are advantages in portable testers. The major components of the portable laboratory may include: · A custom-made machine, plus auxiliary materials, for grinding and polishing small, mounted or unmounted metal specimens · A right-angle head, electric drill motor with attachments and materials for grinding and polishing selected spots on large parts or assemblies. It is also used for driving the grinding and polishing machine described in the previous item · A portable microscope, with camera attachment and film for use in photographing metallographic specimens · Equipment and materials for mounting and etching specimens · A handheld single-lens reflex 35-mm camera, with macrolenses and film · A pocket-size magnifier, and a ruler or scale · A hacksaw and blades for cutting specimens · Portable hardness tester · Acetate tape, acetone, and containers · RTV rubber for replicas Service History. The availability of a complete service history depends on how detailed and thorough the record keeping was prior to the failure. A complete service record greatly simplifies the assignment of the failure analyst. In collecting service histories, special attention should be given to environmental details such as normal and abnormal loading, accidental overloads, cyclic loads, temperature variations, temperature gradients, and operation in a corrosive environment. In most instances, however, complete service records are not available, forcing the analyst to work from fragmentary service information. When service data are sparse, the analyst must, to the best of his or her ability, deduce the service conditions. Much depends on the analyst's skill and judgment, because a misleading deduction can be more harmful than the absence of information. Photographic Records. Photographs of the failed component or structure are oftentimes critical to an accurate analysis. A detail that appears almost inconsequential in a preliminary investigation may later be found to have serious consequences; thus, a complete, detailed photographic record of the scene and failed component can be essential. Photographs should be of professional quality, but this is not always possible. For the analyst who does his own photography, a single-lens reflex 35-mm or larger camera with a macrolens, extension bellows, and battery-flash unit is capable of producing excellent results. It may be desirable to supplement the 35-mm equipment with an instant camera and close-up lenses. Techniques and lighting are discussed in more detail in the article “Photography in Failure Analysis” in this Volume. When accurate color rendition is required, the subject should be photographed with a color chart, which should be sent to the photographic studio for use as a guide in developing and printing. Some indication of size, such as a scale, coin, hand, and so forth, should be included in the photograph. Samples should be selected judiciously before starting the examination, especially if the investigation is to be lengthy or involved. As with photographs, the analyst is responsible for ensuring that the samples will be suitable for the intended purpose and that they adequately represent the characteristics of the failure. It is advisable to look for additional evidence of damage beyond that which is immediately apparent. For failures involving large structures or key machinery, there is often a financially urgent need to remove the damaged structure or repair the machine to return to production. This is a valid reason to move evidence, but a reasonable attempt must be made to allow other parties, who may become involved in a potential legal case, to inspect the site. All concerned parties then can agree on the critical samples and the best way to remove them. If all parties are not available, care must be taken not to damage or alter critical elements to avoid spoiling evidence. Guidelines governing sample collection are covered in ASTM E 620, E 860, E 1020, and especially E 678. It is also recommended that samples be taken from other parts of the failed equipment as they may display supportive damage. It is often necessary to compare failed components with similar components that did not fail to determine whether the failure was brought about by service conditions or was the result of an error in manufacture. For example, if a boiler tube fails and overheating is suspected to be the cause, and if investigation reveals a spheroidized structure in the boiler tube at the failure site (which may be indicative of overheating in service), then comparison with an unexposed tube will determine if the tubes were supplied in the spheroidized condition. As another example, in the case of a bolt failure it is desirable to examine the nuts and other associated parts that may have contributed to the failures. Also, in failures involving corrosion, stress-corrosion, or corrosion fatigue, a sample of the fluid that has been in contact with the metal, or of any deposits that have formed, will often be required for analysis. Abnormal Conditions and Wreckage Analysis. In addition to developing a history of the failed part it is also advisable to determine if any abnormal conditions prevailed. Determine also whether events—such as an accident—occurred in