Joining of Beryllium

Goldberg, A

Lawrence Livermore National Laboratory

关键词: Mechanical Properties;    Manuals;    Nuclear Properties;    36 Materials Science;    Electrochemical Corrosion;   

DOI  :  10.2172/899099
RP-ID  :  UCRL-TR-224718
RP-ID  :  W-7405-ENG-48
RP-ID  :  899099

美国|英语

来源: UNT Digital Library

【 摘 要 】

A handbook dealing with the many aspects of beryllium that would be important for the users of this metal is currently being prepared. With an introduction on the applications, advantages and limitations in the use of this metal the following topics will be discussed in this handbook: physical, thermal, and nuclear properties; extraction from the ores; purification and casting of ingots; production and types of beryllium powders; consolidation methods, grades, and properties; mechanical properties with emphasis on the various factors affecting these properties; forming and mechanical working; welding, brazing, bonding, and fastening; machining; powder deposition; corrosion; health aspects; and examples of production of components. This report consists of ''Section X--Joining'' from the handbook. The prefix X is maintained here for the figures, tables and references. In this section the different methods used for joining beryllium and the advantages, disadvantages and limitations of each are presented. The methods discussed are fusion welding, brazing, solid state bonding (diffusion bonding and deformation bonding), soldering, and mechanical fastening. Since beryllium has a high affinity for oxygen and nitrogen with the formation of oxides and nitrides, considerable care must be taken on heating the metal, to protect it from the ambient atmosphere. In addition, mating surfaces must be cleaned and joints must be designed to minimize residual stresses as well as locations for stress concentration (notch effects). In joining any two metals the danger exists of having galvanic corrosion if the part is subjected to moisture or to any type of corroding environment. This becomes a problem if the less noble (anodic) metal has a significantly smaller area than the more noble (cathodic) metal since the ions (positive charges) from the anodic (corroding) metal must correspond to the number of electrons (negative charges) involved at the cathode. Beryllium is anodic to almost all metals; thus, when joined to other metals and exposed even to a mild environment it may be susceptible to corrosion. In designing a Be-metal joint one must also consider the environment to which the assembled component will be exposed in service.