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What is welding?
Jan 24, 2018

Definition of Welding:

Welding is the process and the way of bonding between two workpieces by heating, pressurizing, or both, using or not filling materials. Welding is widely used for both metal and nonmetal.

A method of bonding is called welding by heating or pressurizing or both and using or not filling the material.

Welding can not only solve a variety of steel connections, but also can solve the aluminum, copper and other non-ferrous metals and titanium, zirconium and other special metal materials, and thus has been widely used in machinery manufacturing, shipbuilding, marine development, automotive manufacturing, petrochemical, aerospace technology, Atomic energy, electricity, electronic technology and construction departments. According to the industrial developed countries statistics, only need to carry out welding process after the use of steel on the total output of about 45%.

Pre-welding preparation work

1. Check assembly clearance and groove angle. The purpose of the groove of the weld edge is to ensure full penetration of the weld during the welding process to form a firm joint. Proper processing of groove is necessary to ensure welding quality.

2. Clear the surface of the groove. In order to ensure weld quality, before welding must be the groove surface of the oil, paint, rust and other impurities clean, range is the weld on both sides of the 20-30mm, must make the groove surface metal luster.

3, the welding rod, the flux according to the stipulation drying, the heat preservation, the welding wire needs to go oil, the rust, the protection gas should keep dry.

4, the selection of welding machine and its polarity;

5, the positioning welding method to fix the relative position between the welding parts to prevent welding parts in the process of deformation, so that welding operations can be normal.

6, in order to make the welding slowly and evenly after welding, to prevent cracks in weld and heat affected zone, to preheat the solder.

7, after the assembly, the joint should be inspected, qualified rear can be applied welding.

Welding Common Sense

1, generally according to the strength of steel to select the appropriate electrode, at the same time consider the size of the welding structure, shape, groove, working conditions, stress, comprehensive analysis of the need for the use of welding electrodes and technical measures.

2, the weld cooling speed, so that the strength of the weld easily generated cracks, can be selected than the strength of the base material lower level of the electrode.

3, the thick plate multi-layer welding or after welding normalizing treatment, etc., to prevent weld strength too low phenomenon.

4, the same strength level of the acid electrode or alkaline electrode selection, mainly consider the shape of the workpiece structure, steel thickness, working conditions, and so on, the general requirements of good plasticity, high impact toughness, strong resistance to crack, to choose alkaline (low hydrogen) electrode.

5, for the carbon steel and low alloy steel or low alloy steel and low alloy steels welding, the general selection of steel with lower strength grade corresponding to the electrode.

6, the welding of medium carbon steel, because of the high content of carbonaceous steels, increase the welding crack tendency, can choose low hydrogen electrode. and take preheating and cooling measures.

7, cast steel welding, cast steel carbon content is very high, and thick, complex shape, very easy to produce welding cracks, when the alloy steel element content more prominent, general selection of low hydrogen electrode, must take preheating and corresponding technological measures.

8. Provide the current range of welding electrodes for reference only. Workpiece preheating can be lower than normal current 5%~15%, the use of DC can be compared to 10% or so, vertical welding and welding than welding current small 10%~15% about.

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