co2气保焊气孔分析

1、co2气保焊气孔分析analysis of the causes of porosity in c02 gas shielded welding stomac02 electric arc welding, the we 1 d pool surface without slag cover, c02 air and strong cooling effect, thus the molten metal solidification is faster, but the gas too late to escape, it is easy to produce in the pores in

2、 the weld.there are 3 possible types of pores: carbon monoxide pore, hydrogen pore and nitrogen pore.one reason, carbon monoxide pores co stoma, mainly in the pool of feo and c reduction reaction occurs as follows: feo+c二二fe+co, the reaction in the crystallization temperature of the molten pool, was

3、 relatively intense, because when the molten pool has been solidified, co gas is not easy to escape, so the formation of pores in the weld in co.if the welding wire contains eno ugh deoxidizing elements si and mn, and the carbon content in the welding wire is limited, the reduction reaction can be s

4、uppressed, and the generation of co porosity can be effectively prevented. therefore, in c02 arc welding, as long as the welding wire is chosen properly, the possibility of producing co porosity is very smal1.two. hydrogen holeif the molten pool is dissolved into a large amount of hydrogen at high t

5、emperature, it will not be discharged sufficiently during the crystallization process, and then the porosity will remain in the weld metalthe hydrogen in the arc zone mainly comes from the welding wire, the oil stain and rust on the surface of the workpiece, and the moisture contained in the c02 gas

6、 0订 is hydrocarbons, and rust contains crystalline water, which decomposes hydrogen at high temperatures to reduce the dissolved amount of h2 in pool, not only can prevent hydrogen porosity, but also improve the ductility of the weld meta 1. therefore, on the one hand, before welding to properly rem

7、ove the workpiece and welding wire surface oil and rust, on the other hand should be used as low as possible with low moisture c02 gas moisture in c02 gas is often the main cause of hydrogen holein addition, hydrogen is dissolved in the molten pool in ionic form. when the dc polarity is reversed, th

8、e molten pool is negative it emits a large amount of electrons, and the hydrogen ion on the surface of the bath pool is compounded into atoms, thus reducing the amount of hydrogen ions entering the molten pool. therefore, when the dc polarity is reversed, the hydrogen content in the weld is 1/3 to 1

9、/5 when the cathode is positive, and the tendency of producing the hydrogen gas hole is smaller than that of the positive polaritythree, nitrogen holethe source of nitrogen: first, the air intruded into the welding zone; two, the c02 gas was impure the test shows that when the short circuiting trans

10、ition occurs, c02 (n2) =3% nitrogen is added to the c02 gas, and nitrogen (n2) =4% nitrogen is not produced in the transition of the jet, but no nitrogen hole will be produced while the normal gas containing nitrogen rarely, phi (n2)二 1%. it can be inferred from the above that the possibility of nit

11、rogen porosity is not very large due to the impurity of c02 gas the main reason for producing nitrogen pores in the weld is that the gas layer is destroyed and a large amount of air invades the welding zonethe factors causing the failure of the gas reservoir include: too small c02 gas flow; the nozz

12、le is partly blocked by spatter; the distance between nozzle and workpiece is too large; and the welding site has side windtherefore, it is the key to prevent the nitrogen hole in the weld to increase the c02 gas flow, ensure the smooth flow of gas and the stability and reliability of the gas reserv

13、oirin addition, the technological factors also influence the formation of stomata the higher the arc voltage, the greater the possibility of air intrusion, the more likely it is to produce air holes the welding speed mainly affects the crystallization speed of the weld pool. the welding speed is s 1

14、 ow, the molten pool crystallization is slow, the gas is easy to escape; the welding speed is fast, the molten pool crystallization is quick, then the gas is not easy to discharge, easy to produce the blowholecommon defects of c02 semi-automatic welding and their causeswelding, semi-automatic, defec

15、tcauses of defectsporosity: c02 gas impure or insufficient gas supplyinvolvement in air during weldingthe preheater doesn，t workthe wind is large and the protection is incompletethe nozzle is blocked and obstructed by spatterthe nozzle and the workpiece distance is too largethe welding surface conta

16、mination, oil, rust, moisture is not clearthe arc is too long, the arc voltage is too highto wire welding silicon, manganese deficiencythe arc is too long and the arc is too highwelding speed is too fastwelding current is too bigimproper position of welding wireincorrect swing of welding wirenot wel

17、ding penetration, welding current is too small, the wire is not uniformarc voltage is too low or too highwelding speed is too fast or too slow (in the groove)the groove angle is small and the clearance is too smallimproper welding wire position, centering errorpoor weld formation. improper technical

18、 parametersimproper welding wire position, centering errorthe center deviation of the feeding rollerthe adjustment of welding wire straightening mechanism is improperthe conductive mouth is loosepear shaped crack: too much welding currentgroove is too narrowthe arc voltage is too lowimproper welding wire position, centering errorarc instability: loose or w