1) the principle of strong matching
That is, the selected electrode, the deposited metal tensile strength equal to or similar to the tensile strength of the metal to be welded, this method is mainly applied to the selection of structural steel electrode, in theory, that the weld strength should not be too high The strength of the material, or often due to poor weld cracking or stress concentration and other reasons, the quality of welded joints decreased.
(2) and other toughness matching principle
That is, the toughness of the selected weld metal is equal or similar to the toughness of the metal to be welded. This method is mainly suitable for the selection of low alloy high strength steel electrode. In this way, when the base metal structure rigidity, stress complex, will not be due to plasticity or toughness joints caused by joint damage.
(3) and other ingredients match the principle
The selected electrode deposited metal chemical composition of the welded or close to the base metal. This method is mainly applied to stainless steel, weathering steel, heat-resistant steel electrode selection, so that we can ensure that the weld metal has the same as the base metal corrosion resistance, heat resistance and other properties and with the parent metal has a good fusion and matching.
(4) According to the special requirements of the principle of selection
★ selection of welding electrodes should be based on the requirements of surfacing layer is generally anti-wear or impact wear; is intermetal wear or abrasive wear or corrosion medium wear; is high or normal temperature wear; is a single wear or synthetic wear and other different situations Selection of surfacing electrode.
★according to the weld metal need to be machined or heat treatment and the economic acceptability of the electrode to choose the electrode. This method is mainly applied to cast iron welding electrodes, welding electrodes, heat-resistant steel electrodes, stainless steel electrode selection.
★ Where the requirements of the weld metal with high ductility, high toughness, and the corresponding strength indicators, should be preferred alkaline low hydrogen type electrode.