IIW History 1948-1958

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and, if possible, the classification of the so-called weldability tests used in the different countries. A questionnaire having been prepared in 1950, the Com– mission was able in 1952 to adopt a classification of weldability tests; this clas– sification was put forward by Mr. H . GRANJON (France) in a report which was approved for publication - Proposal for a classificat·ion of weldability tests (1) . A little later the Commission approved the publication of another report - Weldability tests on mild steel - Enq'Ufry on their practical applic– at1:on - Febru.ary 1956 by Mr. M. HANSF.N (Denmark) in which the author indicated the use to which the principal weldability tests were put in practice, in accordance with the aspects of the problem studied. Each year the rapporteur makes a report to the Commission on new tests mentioned in the technical literature and classifies them in accordance with the system adopted by the Commission. B. Brittle Fracture Tests. At the first meeting in Delft in 1949, it was agreed that a general study should be undertaken on the various brittle fracture tests then known. The terminology relating to the appearance of the fractures was agreed upon and, in 1950, a plan for the classification and comparison of the tests was prepared, while each delegate was invited to inform the Commission of the results obtained with the various tests used in his country. The first important consequence of this investigation was the provisional recommendation, adopted at Oxford in 1951, regarding the use of the impact test on a V-notch testpiece (the so-called Charpy V-notch testpiece with a notch of 45° included angle, 2 mm in depth, with a radius of 0.25 mm at the bottom of the notch). The test was to be carried out at six temperatures, using two testpieces for each temperature. This recommendation was confirmed in 1952 and supplemented in 1953 by a rider to the effect that the appearance of the fracture should be noted as well as the fracture energy. In the meantime, the comparative study of the different types of testpiece was being continued, both from the theoretical (study of the state of stress at the bottom of the notch) and the practical point of view, in particular by means of an international programme of experiments carried out by Sub-Commission A. At the beginning (1952), the object· of these experiments was to compare the results obtained with various steels from the Charpy test on a V-noteh testpiece (fracture energy and appearance of fracture) on the one hand, and from the slow bend t est on a notched bar (appearance of fracture) proposed by Mr. VAN DER VEEN (Netherlands). This investigation has not yet been completed but it has revealed that, in spite of generally satisfactory agreement, certain differences in classification of the steels may occur, depending on whether judgement is based on the energy criterion or on that of the fracture appearance; these differences are systematic rather than fortuitous. They are, however, likely to be explained by the work in hand in which other testing t echniques (Robertson, Pellini) are being used and in which all the properties of the steels experimented upon are being more closely examined. However, on the Commission's approving a recommendation concerning '''eldable steels (2) in which the fracture energy values obtained with Charpy V-notch testpieces were fixed, there arose the question of laying down the condi– tions for executing and interpreting the test, as regards the number of specimens to be tested and the information given by the results. The necessary experi– mental work ,-vas undertaken outside the II\iV by a group of European steel-

(1) Document IX-26-53. (2) See below.