IIW History 1948-1958

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out that it was possible t o find a solution in 1957· For these t ests the Scandina– vian experts recommended the use of a drilled t estpiece fo r tensile test s, while the experts from the other countries were accustomed to use an ordinary tensile t estpiece. In the draft document which is mentioned under the heading « \i\Tork in hand » below, the use of one or other of the t wo t estpieces is envisaged for determining the compatibility of filler metals and plates. At the IIW annual assembly held in July 1957 at Essen, a working group was set up to complete the second series of t est s. The results obtained will enable the provisional document entitled T ests for the sm:tabihty of a steel f'iller rod for the base (parent) metal (1) to be put into its final shape. This document will be complementary to that previously prepared on the classification of filler rods and the two t ogether will form a very useful basis for defining the properties of filler rods used in gas welding. Sub-Commission A was established by decision of the Governing Council at the Florence assembly in 1954· It has met eight times since then, three times in P aris (January 1955, December 1955, May 1957), t wice in London (March 1955 and November 1957) and in Zurich (September 1955), Frankfort (February 1956), Lausanne (May 1956) and Copenhagen (F ebrua ry 1957). Its initial work was on the subj ect of brazing temperatures. This work \vas based on a large number of tests carried out principally by Mr. EvRARD (France), Dr. COLB s (Germany) and Dr. BLANC (Switzerland) and led to the preparation of the document Defin-itions and recommendat1:ons relating to brnzing, soldering and bi-aze welding (bronze welding) which was approved and recom– mended for publication by the Governing Council in July 1956 at Madrid. This document first gives the corresponding terms in English, French and German of some currently used concepts relating to the technique of brazing a nd, after defining the working temperature and the wetting temperature, reaches the following conclusions : B. Sub-Commission A « Brazing and Surfacing ».

l. The wetting t emperature is a characteristic of the brazing proces5.

2. The working t emperature is a characteristic of the filler metal in brazing.

3. In the operation of brazing, the wetting temperature lies between certain limits. The lower limit is generally lower than the liquidus of the filler metal. .+ . The lower limit of the wetting temperature corresponds t o the t empera– ture at which bonding bet ween the filler metal and the parent metal is still possible; the upper limit corresponds to the working temperature. s. The te st s carried out show that for braze welding these limits, for different parent met als and the usual filler metals (60/40 brass + silicon and German silver + silicon), a re approximately 775° C for the lower limit and 900° for the upper limit when used with steel and cast iron.

6. In brazing (hard-soldening), the upper limit is aenerally attained.

(1) Doc ument I -53-5 7.