How To Weld Titanium?

Titanium metal has a low specific gravity (specific gravity of 4.5), high strength, good resistance to high and low temperatures, excellent resistance to cracking and corrosion in wet chlorine gas. The mechanical properties and welding of titanium are related to the purity of the titanium material, the higher the purity, the better the performance, the lower the purity, the plasticity and toughness drop sharply, the worse the welding performance.
1, the metal properties of titanium and welding parameters
Titanium at 300 ℃ above the strong viability, easy to absorb hydrogen, oxygen and nitrogen atoms at high temperatures, so that the material becomes brittle. Titanium at a high temperature of 300 ℃ began to absorb hydrogen, 600 ℃ absorption of oxygen, 700 ℃ began to absorb nitrogen.
Argon arc welding machine should have a high-frequency arc, current attenuation, gas time-delay protection, pulse device wire requirements and the mechanical properties of the parent material equivalent.
Protective cover material should be selected purple steel or titanium material, shape in order to protect the weld, to achieve the weld does not change color, the shield should be added stainless steel wire mesh, to play the role of gas buffer.

2, titanium welding operation technology
Cleaning before welding:
Material with a rolling angle machine to beat the bevel, with a wire brush to polish both sides within 25mm of the oxide skin, grease, burrs, dust, etc., and then wipe with acetone or ethanol.
Welding protection:
Before welding to learn argon protection, protection, one person to take the shield to protect the top, another person to take the shield to protect the bottom, the protector must be good with the welder, after welding to wait until the weld is cooled down before you can release the protective cover, single-sided welding double-sided molding special attention to the back of the protection, if not protected, the weld will not be able to flow, and there is no molding.
Welding, the weld should leave enough gap 3-5mm, easy to form the arc pit, right hand holding the torch as low as possible torch tungsten electrode, the left hand holding the wire, using the thumb and middle finger clamping the wire forward, send the wire to maintain the continuity and stability of the two hands should be well coordinated between the two hands to keep the seam flat, the eyes should always be observed to the depth of the molten pool and the flow of solder, the current should be adjusted in accordance with the provisions of the current is prohibited from being too large.
The nozzle argon gas is kept at 5ml, the protective gas is kept at 25ml, and the back is kept at 20ml to ensure that the weld does not change color after the protective shield. Two times welding, to leave a certain amount of cooling time, so that the surface temperature down to below 200 ℃, otherwise it is very easy to produce crack embrittlement, the welding position as far as possible to use the flat welding and tube mouth rotation welding.
When welding the house should be dry and dust-free, wind speed less than 2 m / s, windy easily caused by arc instability, capping welding as much as possible to use pulse devices, so that the weld seam molding beautiful.
3, titanium equipment manufacturing process and maintenance technology
Processing titanium tube, titanium elbow, titanium tank material to meet the requirements of its toughness, strength, expansion and contraction to have a plate certificate of conformity, each sheet of titanium plate must be corrected with a ruler, count the size of the material, to stop the scraps are too large, cut the plate should be used in the shearing machine, try to avoid the use of gas cutting, the use of pipelines should be scribed clearly and accurately, strictly prohibit the repeated use of gas cutting, cut off the plate after the use of a chamfering machine hit a good bevel, the break required uniformity Consistent, rolled plate machine rolled plate after the initial molding, weld to concave a little inward, easy to weld after 2 plastic, because of the high price of titanium materials (raw materials 140 yuan / Kg or so, after processing 400 yuan / Kg or so) to eliminate waste.
Titanium plate maintenance and processing are very different, mainly due to environmental factors, material changes, etc., the weld can protect the protection, really can not be protected on both sides of the use of low-current one-sided protection, weld cracks can not be welded in the original weld to be used to make up for the way the plate is welded, the weld site is generally windy to have a wind device, the use of raincoats or iron plates to cover the takeover because of the inside of the unprotectable to leave gaps or staggered weld The weld should be widened and thickened appropriately.