Electrode Core-wire Composition
According to AWS A5.1—81, the core wire for the electrodes in this specification is usually a rimmed or capped steel having a typical composition of 0.1% C, 0.45% Mn, 0.03% S, 0.02% P, and 0.01% Si. IS : 2879-1975 recommends rimming quality steel with the following composition (maximum percent) 0.1% C, 0.38—0.62% Mn, 0.03% S, 0.03% P, 0.03% Si, 0.15% Cu.
4.3.4 Factors Affecting Electrode Selection
Each situation needs a number of factors to be considered before specifying a particular electrode. These factors are:
(a) composition of metal to be welded
(b) mechanical properties desired in the joint
(c) weldability problems — any risk of weld metal cracking
(d) heat input limitations
(e) welding power source available a. c. or d. c.
(f) welding position
(g) type of joint
(h) parent metal thickness
4.3 MILD STEEL AND LOW-ALLOY STEEL ELECTRODES
Having answered these and other questions relevant to the specific situation an electrode type and size is selected which gives desired performance at minimum cost. The electrodes are marketed by different manufacturers in different brand names. They also give a standard code number based on international or national standards. These code numbers are useful in comparing the electrodes from different manufacturers and in knowing the characteristics of the electrodes completely regarding the mechanical properties of the weld deposit, type of covering, type of current (a. c./d. c.) and welding positions in which the electrode can be used. These standards are explained further in the following paragraphs.