IIW History 1948-1958

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a) without pre-heating, of non-alloy steels containing less than 0-4 % carbon, b) with pre-heating, of the same steels,

c) of other qualities of steel, d) of certain non-ferrous metals.

Points a) and b) of this programme have been covered by two documents (1) approved by Commission III and recommended for publication, the first in 1956 and the second in 1957 · The Sub-Commission is pursuing its work and expects to submit a new report in 1958.

D . Spot Welding of Low Alloy High Tensile Steels.

Discussing the conditions for the spot welding of mild steel, Commission III, m 1951, felt it necessary t o define what was understood by a good weld and, to this end, to lay down a simple t esting method which a ny user could easily apply. The attention of members was dra\vn to work carried out in this fieltl by Mr. P. J o llIAT (France) in regard to low alloy high tensile steels, used in par– ticular in the construction of raihvay carriages. In 1952 lVIr. ] OUMAT submitted to the Commission, a paper Proposition regarding the de/ i11ition of a good weld and the adoption of a practical method of testing to ve1'i fy th e qu.ality of spot welds ; this paper relates to the hi o-h tensile steels already mentioned and the proposals were based upon quality control of spot welds by means of a torsion shear test. Fur Lltis Lest , the testpiece consist s of two square plates 55 mm long on each side, welded together at their centre by the spot weld to be checked. The test consists in separating the two plates by applying to them slowly, and without a ny sudden increases of pressure, a torsional stress up t ') fracture. The interpre– tation of the result is carried out by visual examination , either with the naked eye or through a magnifying glass, of the fracture, and by comparing it with t ypical fractures taken as references . The appearance of this torsional fracture is sufficient to evaluate a good weld. Very complete experiri1ents were undertaken in Belgium, Italy, Sweden and the United Kingdom on the basis of the proposals put forward b y the F rench delegation. The results obtained confirmed the conclusions reached and led the Commission to recommend the publication of the fin al report by lVIr. J ouM.-\T: A New ~tf ethod for the Pract1:ca/ T esting of the Quality of Spot Jtl' elds made in em-I-hard Low Alloy Steels (z) . The document describes the « torsion shear » method of testing which was adopt ed, and indicates the t ype of fracture " ·hich should occur in a spot weld of good quality on these st eels. In addition to this document, Commission III recommended the publication of a paper submitted b y the same author vvith the title « Determination of Sethngs for electroni:cally controlled Weldin g Machines »accompanied by a cc Setting table » (3) . By keeping, for the same type of assembly, onl y two variable para– meters out of the t en which make up the welding sequence, this method greatly simplifies the settings for the welding of grades of steel fo r which a complex welding sequence is necessary.

(1 ) Docnmeuts III-59-56 and III-68-56. (1 ) Document III-35-5-l· (3) Document III-3-l-5+