Understanding the best welding practices is important, especially for small businesses. Using titanium when welding can be tricky. For example, if there are blue, green, grey, violet, or white colors in titanium after welding it means there is an atmospheric contamination. Ensuring welding is up to standard is important for safety and quality.
Titanium is very resistant to corrosion. It is lighter than steel, heavier than aluminum, and stronger than both of those metals. Titanium is cheaper in the long run because it needs little service, maintenance, and repair. However, it is expensive initially. Titanium is used for military, aerospace, medical, recreation, chemical processes, and metal finishing purposes.
There are three welding practices that should be adopted. First, it is important to shield the heat-affected zone from the atmosphere until the temperature drops below 800 degrees. The titanium should not begin absorb oxides (oxygen, nitrogen, hydrogen, carbon) until the temperature is below that median.
If they are absorbed too early, the weldment will be embrittled and the piece rendered useless. A good practice would be to test a piece out first before welding the main titanium project. The variables that allow good shielding gas coverage should be verified before beginning.
Second, the work area needs to be clean. Contamination can occur from many different sources. There is oil on fingertips, lubricants, cutting fluid, paint, dirt, and more. These can cause embrittlement and weld failure. The work area should be free of dust, debris, and excess air movement that would interrupt the gas shielding mentioned above.
Third, it is vital to use the correct tools to weld titanium. A power source with a high frequency arc starting, an output of 250 amps, a post-flow shielding gas timer, and remote amperage control capabilities is the first and most important tool needed. Polarity should be set to straight.
A torch can be air or water cooled, based on personal equipment preferences. Water cooled torches are smaller, maneuverable, and can weld at higher temperatures for extended periods. Water cooled torches are easier, but air cooled torches are less expensive.
To carry the required welding current, a 2%-ceriated tungsten sized is appropriate. A glass lens is needed to evenly distribute and create smooth gas flow. A cup with a diameter of at least - 1 inch should be used. Larger cups enable larger welds.
A trailing shield should extend the length of the weldment. The electrode should extend longer than normal to provide extended gas coverage if using larger cups or the trailing shield. Normally, the electrode extends far enough for visibility and access to the joint. This can also be calculated as one and half times the diameter of the electrode.
Purge blocks are needed to provide shielding gas coverage on the back and bottom of a joint. Many places create their own custom purge blocks from porous copper sheet and stainless steel. The copper acts as a gas lens by evenly distributing gas. The blocks are filled with stainless steel wool to smooth gas flow even more.
Sometimes there are awkward joints. Instead of purge blocks, welders can create shielding gas dams or chambers with stainless steel foil and fiberglass tape. Gas must flow long enough to exchange gas inside the chamber ten times prior to welding. This ensures purity.
A gas manifold system distributes shielding gas to the torch and purge blocks. It accomplishes this by using separate gas lines with surgical grade tubing, ensuring quality. Moisture content will rise as cylindrical pressure drops, so cylinders should be switched when the pressure reaches 25 bar.
By having appropriate equipment, keeping a clean work area, and utilizing gas shielding correctly, titanium welding projects will not have embrittlement or failure. These practices are important to ensure quality and safety. Welding titanium appropriately in the beginning will allow for longevity and low maintenance.
