Select the principles of welding rod
First, the principle of selection considerations for the weldment physical and chemical properties and chemical composition:
1 strength point of view, to choose to meet the mechanical properties of the parent material of the electrode, or a combination of mechanical properties of the base metal electrode, or strong combined base metal weldability, switch to non-strength and good weldability electrode, but considering the weld strength of structural type, in order to meet stiffness requirements
2 then the alloy composition in line with or close to the base metal
Higher base metal carbon, sulfur, phosphorus and harmful impurities, good crack resistance and resistance to stomatal performance of the electrode. Suggested the use of titanium dioxide calcium type, ilmenite-type electrode. If you still can not solve, you can selection of low hydrogen type electrode

Second, the principle of selection consideration for the working conditions of the weldment and the use of performance:
To withstand dynamic loads and shock loads, in addition to ensuring the strength, impact toughness, elongation and uniform have high requirements should be followed by selection of low hydrogen type, titanium calcium and iron oxide-type electrode
Contact with corrosive media, must be based on the types of media concentration, operating temperature, as well as the distinction between general corrosion or intergranular corrosion, etc., select the appropriate stainless steel electrode
Work wear conditions should distinguish between general or by the impact wear, under wear at room temperature or one hundred high-temperature
Work under very warm conditions should be selected to ensure that low-temperature or high temperature mechanical properties of the electrode

Three considerations: the principle of the weldment geometry the complexity of the beginning, the stiffness of the size of the weld groove preparation situation and welding position:
Complicated shape or large thickness of the weldment, the weld metal shrinkage in the cooling stress, prone to crack, the crack resistance of the electrode must be selected, such as high toughness welding rod of low hydrogen type electrode or iron oxideTypes Of Welding Electrodes

(2) the conditions can not flip the weldment to be used can all position Welding Electrode Material

(3) welding the weldment parts difficult to clean up the selection of strong oxidizing acid electrode is not sensitive to the oxide and grease to avoid holes and other defects

Considerations Shi welders to equipment selection principle:
DC welder, should not be selected to limit DC power supply electrode, welding rod should be used in AC-DC power supply. Certain steel products (such as the elimination of heat treatment after welding of pearlitic heat-resistant steel) need, but by the equipment constraints (or structural constraints) can not be heat treated, it should use the non-base metal material welding rod (such as austenitic stainless steel electrode), may do not have to weld heat treatment

Principle of the five considerations in order to improve the welding process and to protect the health of workers:
Acid electrode and alkaline welding rod to meet the requirements, maximize the use of acid electrode

Six considerations: labor productivity and economic rationality principle of selection:
Use the same performance, you should try to choose the lower prices of acid electrode, rather than alkaline electrode, especially in the acid electrode titanium, titanium calcium type for your situation of China's mineral resources should be vigorously promoted

PS
A general carbon steel and low alloy steel welding principles:
One should make the strength of welded joints is greater than the minimum intensity of welded steel
Should be not less than welding steel ductility and impact toughness of welded joints
(3) In order to prevent welding cracks should be selected according to the poor weldability of the base metal welding processes

Two low-alloy steel and austenitic stainless steel
(1) is generally used in chromium nickel higher than the base metal, plastic, crack resistance, good austenitic stainless steel electrode
2 selected corresponding to the stainless steel electrode for unimportant welding,

Third, the welding of stainless steel composite plate
Recommend using the electrode of the primary, transitional, stratified in three different performance
General, the grass-roots level with the corrosive medium of the composite plate without direct contact with the commonly used carbon and low alloy structural steel, welding at the grass-roots level can choose the appropriate level of structural steel electrode
(3) transition layer in the junction of two different materials should be used with chrome-nickel clad steel plates, plastic, good crack resistance of austenitic stainless steel electrode composite layer directly in contact with the corrosive medium, the choice of austenitic stainless steel
Current options: I = 10 * D * D (empirical formula),
The SMAW how welding goggles and face masks?
The greater the welding current, sunglasses tablets should be more black, the same mask, and the best clothing are not afraid of burning, or burning does not love to spread.