What is the treatment of the black spots generated when welding titanium plates by argon arc welding

I don't think it's a question of how to polish the black spots at the root. Instead, it is technically improved, and if you don't improve, you will always have black spots when you weld it, and you will always have to polish it, and you will always waste money.

The correct weld is golden or blue, and the gray and black indicates that there is a problem with the welding. There are many reasons that affect TIG welding, and the following tells you what questions you have about the basic influencing factors, and we can also work together

Argon arc welding parameter improvement project.

Data collation 1. Influencing parameters of argon arc welding effect.

1.Gas flow.

2.Current.

3.Arc voltage.

4.Walking speed.

5.Arc length.

6.Tungsten needle head shape and angle.

7.Weld rod size.

8.Welding rod angle.

9.Welding rod material.

10.Workpiece material.

11.Bead weld shape and size.

12.Operational techniques.

Second, the influence of each parameter.

Gas flow - plays a protective role, high temperature, isolates the air, stabilizes the arc.

The magnitude of the gas flow rate and the purity of the gas.

If the traffic is too large or too small, it will be affected, and you should choose an appropriate value.

Effect of electric current.

Current can be divided into current types and current magnitudes.

Current type: 1DC cathode --- suitable for welding carbon steel, low alloy steel, stainless steel, etc.

The weldment is a positive electrode, and all the energy released when subjected to electronic bombardment is converted into heat energy, and the welding molten pool is deep and narrow, which is conducive to the connection of metals, and the welding internal stress and deformation are small, and the welding productivity is high.

Tungsten electrode is not easy to overheat, has a long service life, and has a large allowable current value.

The tungsten electrode has strong electron-emitting ability and stable arc.

There is no cathodic crushing, so it cannot weld aluminum, magnesium and their alloys, but it is widely used in the welding of carbon steel, low alloy steel, stainless steel, nickel-based alloy, titanium alloy, copper alloy, etc.

2.DC reverse polarity --- suitable for welding active metals such as magnesium and aluminum alloys.

Two extremely important physical phenomena arise, namely "cathodic breakage and tungsten overheating".

3.AC -- suitable for welding aluminum, magnesium, beryllium copper alloys, etc.

The magnitude of the current: the penetration depth increases significantly (proportional) when the current increases, the melting width is almost unchanged, and the residual height becomes larger, h=kml

Arc voltage. As the voltage increases, the weld height increases significantly, and the penetration depth and residual height decrease slightly.

The melting width and depth of the walking speed are significantly reduced, and the residual height is slightly reduced.

Arc length. The welding distance is as far away as possible, but it should not be too close, and the electrode is generally no more than 3mm away from the workpiece

Tungsten needle head shape and angle.

The shape of the head of the tungsten needle is related to the type of current, and the correct processing shape of the tungsten electrode tip before welding is as follows

DCSP (Straight Positive), DCRP (Straight Reverse Pole), AC (Alternating Current).

The head is pointed The head is small and rounded at the very end of the head The head is fully rounded.

If you want to remove: clean the passivation paste with stainless steel, which is available on the market. It is a white paste, and the raw materials with high stability are used in the paste, which is a stable paste, does not decompose, does not precipitate, does not contain sulfides, and the amount of chloride ions is strictly controlled, and is used to remove the black residue in the stainless steel weld area oxide scale.

The weld area is white and bright, and the substrate is not corroded.

To fundamentally solve the problem of welding protection, the weld after normal welding should be silvery-white, there should be no other colors, followed by golden yellow, yellow, blue, gray, if to gray-black then it means that the part has been completely oxidized, the material deteriorates, which will seriously affect the mechanical properties of the material. If you need help again, add me.

Try using pickling.

Spray with water and sand, never sand.

The biggest problem of titanium alloy welding is to solve oxidation, because titanium is very easy to be oxidized, you say white, is the appearance after oxidation, the biggest problem is that the protection effect is not, the effect of gas protection must be improved

1. The purity of argon used is that the gas used is generally enough, but now gas manufacturers rarely do it, the higher the purity, the higher the cost, so you buy five 9 purity, which is actually the purity of four 9, or buy gas from big brand manufacturers, my experience is that it is generally more than 150 yuan bottle to use.

2. If the workpiece is not big, make a closed glass container, the size of a TV, put the workpiece and hand into it, fill it with argon in the closed container, so that it is completely protected, until the welding is completed, and the workpiece is cooled and then taken out, it will definitely not turn white.

3. If the workpiece is large, it is necessary to add back protection or gas drag cover.