A Symposium on Effect of Temperature on the Brittle Behavior of Metals with Particular Reference to Low Temperatures, sponsored by the Low Temperature Panel of the ASTM-ASME Joint Committee on the Effect of Temperature on the Properties of Metals, was presented at the Annual Meeting of ASTM in June 1953. The symposium papers and discussion were published as ASTM Special Technical Publication No. 158 which was widely hailed and broadly distributed. That symposium covered the history and evaluation of brittle failure in ships and engineering structures, presented criteria of metal behavior, and touched on metallurgical and mechanical influences, methods, and reliability of notch-toughness tests. It featured experience in testing several of the recently introduced high-strength quenched-and-tempered steels, titanium, and several types of cast irons. During the ensuing years data on brittle fracture in metals increased several fold as a result of continued testing programs, the continued introduction of different alloys and chemical analyses by the producers, and the zeal of numerous organizations in conducting tests designed to indicate the resistance to brittle fracture of metals of special interest to them or dictated by heretofore untried service conditions imposed upon engineering structures and constructions. In the preparation of the current symposium, the Low Temperature Panel decided to seek papers that would relate the vast amount of data and research to the problems of the design engineer of 1961 and attempt to summarize results, such as evaluating the low-temperature properties of specific metallic materials and the test methods used. All efforts were geared to avoid detailed reporting of test data in favor of presenting information of vital interest and directly applicable to problems in designing for low-temperature service. Authors were asked to emphasize their interpretations rather than to dwell at great length on the voluminous test records.