Titanium is extremely difficult to refine. Because it must be isolated, then expensive and complicated chemical processes. Pure titanium means nothing, because it is too soft. In order to make it practical, you must add another metal as an assistant. Of course, the premise of all this is based on the inherent properties of titanium itself. Therefore, what we usually call "titanium" is an alloy with special properties. From a general point of view, titanium is excellent in its high strength, mass ratio (high strength, but light weight), good corrosion resistance, and non-magnetic properties. The main characteristics of thermal expansion and thermal conductivity are small, impact toughness (known by domestic riders as metal reduction) and high anti-fatigue index. In materials science, we call titanium alloys an allotropic metal because it can exhibit different crystal shapes. There are hexagons or cubes.

If titanium is used in industry, the main difficulty is that titanium is sensitive to the loss caused by friction. A simple example is that at high speeds, the chain wears a piece of pure titanium flywheel as sharply as the reaction produced during welding. I think that using such a chemical example to explain will make everyone understand more simple, but not scare people. Although the hexagonal crystal structure of titanium makes it excellent in properties, the temperature can change this structure (here is a chemical change, which does not belong to the same category as the physical changes such as thermal expansion and heat conduction mentioned above). For this reason, we call titanium a saturated crystal structure, so titanium alloys cannot have a little impurity, even a small amount. Otherwise, a crack will appear inside the weld line of the titanium tube. Now that we know about these difficulties, how about welding titanium alloy pipes?

A titanium frame, we can't treat it with an approximation. In the case of welding, in a high temperature environment, all dangerous areas should be isolated by gas so that they are not "infected" by impurities. We call it bath-type melting (Imagine that when you wash a hot bath, your body is surrounded by hot water, as the name suggests). Therefore, our use of gas is called "supervising gas." In the small environment of welding, this gas is inert. We have two ways to create a welding environment. The first method is to use a bell jar. The other method is to maintain an inert gas at the weld. It requires constant flow, rich flow, and constant stability. The whole environment is shrouded. Generally, we use argon and helium because they are easy to provide and are inexpensive. Above the amount, 75% argon and 25% helium are mixed. For some special cases, such as a large welded part, in order to optimize efficiency, an arc is also used to act as a gaseous environment.

Supervising the gas does not guarantee that it will provide an environment that is completely enclosed by gas. After all, the workers still need to contact the pipe when welding by hand. In order to reduce this effect, a good welding workshop will first purify the air environment, and will inject a large amount of neutral gas into this space. All of the significant problems brought about by this are - cost improvement (now everyone I know why the titanium frame is expensive.)

There are three main welding techniques, all using an electric arc.

TIG (Tungstene Inert Gas), this welding method was mentioned in the last Lapierre data for Wang Mutu. Here, a non-meltable electrode made of tungsten is used.

MIG (Metal Inert Gas), which uses a coiled fusible electrode.

PAW, this method is not used in bicycle manufacturing for the time being, mainly for military work.

Attn : Jason

Email: jasontitanium@163.com

Skype: txcanberra