PD 6484:1979

Foreword
Cooperating organizations
Section one. General
1 Scope
2 Conditions affecting corrosion at bimetallic
    contacts
3 Prevention of bimetallic corrosion
Section two. Tables
4 Tabulated data on the behaviour of bimetallic
    couples
Tables
1 Additional corrosion of aluminium and aluminium
    alloys resulting from contact with other metals or
    carbon
2 Additional corrosion of aluminium bronzes and
    silicon bronzes resulting from contact with other
    metals or carbon
3 Additional corrosion of brasses including high
    tensile (HT) brasses (manganese bronze) resulting
    from contact with other metals or carbon
4 Additional corrosion of cadmium resulting from
    contact with other metals or carbon
5 Additional corrosion of cast irons resulting from
    contact with other other metals or carbon
6 Additional corrosion of cast iron (austenitic)
    resulting from contact with other metals or carbon
7 Additional corrosion of chromium resulting from
    contact with other metals or carbon
8 Additional corrosion of copper resulting from
    contact with other metals or carbon
9 Additional corrosion of cupro-nickels resulting from
    contact with other metals or carbon
10 Additional corrosion of gunmetals, phosphor bronzes
    and tin bronzes resulting from contact with other
    metals or carbon
11 Additional corrosion of lead resulting from contact
    with other metals or carbon
12 Additional corrosion of magnesium and magnesium
    alloys resulting from contact with other metals or
    carbon
13 Additional corrosion of nickel resulting from
    contact with other metals or carbon
14 Additional corrosion of nickel-copper alloys
    resulting from contact with other metals or carbon
15 Additional corrosion of nickel-chromium-iron alloys
    resulting from contact with other metals or carbon
16 Additional corrosion of nickel-chromium-molybdenum
    alloys resulting from contact with other metals or
    carbon
17 Additional corrosion of nickel silvers resulting
    from contact with other metals or carbon
18 Additional corrosion of soft solders resulting from
    contact with other metals or carbon
19 Additional corrosion of stainless steel (austenitic,
    with approximately 18% chromium) resulting from
    contact with other metals or carbon
20 Additional corrosion of stainless steel
    (martensitic, with approximately 13% chromium)
    resulting from contact with other metals or carbon
21 Additional corrosion of steels (carbon and low
    alloy) resulting from contact with other metals or
    carbon
22 Additional corrosion of tin resulting from contact
    with other metals or carbon
23 Additional corrosion of zinc and zinc base alloys
    resulting from contact with other metals or carbon

Guidance on the avoidance of situations in which corrosion may arise from bimetallic contacts between different metals and alloys. Discusses the environmental conditions which may lead to such corrosion and gives advice on its alleviation. Annotated tables give the likely behaviour of various couples in five different environments.

This document gives guidance to designers, to help them to avoid situations in which corrosion may arise from the interaction of different metals and alloys at bimetallic contacts.

It comprises two sections. Section 1 gives details of conditions affecting corrosion at bimetallic contacts and methods of alleviating it, and section 2 consists of annotated tables indicating the degree of additional corrosion likely to occur at bimetallic contacts exposed to atmospheric and aqueous environments.

The document does not deal with other environments, such as those encountered in chemical engineering, where the effects may be different, and it does not refer to situations where contact between certain metals, even below their melting point, may lead to some interpenetration and consequential embrittlement.

The metals and alloys are identified in the tables by their generally accepted descriptions, but it will be appreciated that many variations in composition and condition are found in practice. For further information on the behaviour of particular alloys, reference should be made to the appropriate development association, trade association, manufacturer or supplier. In the case of defence stores, further information may be obtained from the appropriate branch of the Ministry of Defence.