IIW History 1948-1958

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makers vvho, a-ft er several years of '''Ork, submitted their conclusions tu the Commission in the s·hape of a report by Messrs H. HERBIET (Belgium) and S. DESCOVITCH (Italy) : Co11tribntion to the stii.dy of an acceptance method of testing jor weldable steels C and D using the V-notch Charpy test on the basis of a conven– honal specimen (1). The statistical analysis of the results showed that it was not normal to specify simultaneously an aver age and a minimum value for three test results . Having evaluated the accuracy on the value of the average, the authors proposed a method called « sequential >> for evaluating the impact strength of the product tested in the most significant way compatible with a relatively small number of testpieces. The same group has also undertaken a systematic study of the van der Veen slow bend t est, the use of which had been proposed, like the impact test, for the qualification of weldable steels. C. Theoretical Study of Brittle Fracture. In the early years of the IIvV all the delegates did most useful work in prov– iding each other with information on the investigations undertaken in each country on the phenomenon of brittle fracture . At present a rapporteur, Mr. P. E. LAGASSE (Belgium), is responsible for presenting, with the help of various delegates, a general report which is discussed at each assembly when any further explanations necessary are given. These disc ussions have shmvn that a satis– factory solution to the problem of brittle fracture is each year nearer in sight . D. Recommendations concerning Weldable Steels. At the Delft meeting in 1949, Mr. vV. BoKHOMME (Belgium) ''"as made res– ponsible for collecting, fo r purposes of compari son, national specifications and standa rds in use in the different member countries concerning steels which might be used in welded construction . From this compa rison it appeared po. sible to p repare an international recom– mendation giving the minimum cha ract eristics of steels considered to be weldable . This recommendation, several draft s of which had been p repared under the direction of Mr. Bo:NHOMl\IE, was approved by the Commission and , at the Zurich assembly in 1955, aft er prolonged discussion, recommended for publication, subj ect to it being mentioned in the introduction to the document that it had given rise to profound differences of opinion. The document was entitled R ecommendahou s to def'£ne the 1111;11i·m.it/ln requirements to be met by rolled and forged carbon or low alloy carbon-manganese stru.ctz,wal steels so that they may be su.1;table for electric arc weldin g. (z) It is impossible to analyse this document in detail here, but t wo essential ]Joints in connexion with it may nevertheless be underlined : a) The recommendation envisages fo ur classes of steel defined by their chemical compositions and possibly also by figures representing their resistance t o brittle fracture. It clearly indicat es that the st eel should be chosen in the light of the service conditions of the construction in question and of the pre– cautions to be taken in fab ricating the construction, precautions summarized in an appendix t o the recommendation drafted by Professor F . RAPATZ (Austria) . In this respect the recommendation is in conformity with the definition of weld– ability prepared by the Commission when it started its work . b) The recommendation envisages, fo r the st eels in the two higher classes, Charpy t est s on a V-notch t est piece and fixes the minimum guaranteed fracture energy at 0°C fo r one and at -20°C for the other. It is therefore implicit that

( r) Docum e nt I X-O:i_J-57· (2) Docu111 nt IX- 115-55.