Titanium is a very active metal. When the temperature exceeds 400°C, it begins to react chemically with nitrogen and oxygen in the air. When it reaches 600°C, the reaction becomes more violent. Titanium reacts with hydrogen, oxygen and carbon. Finally, the generated chemicals deteriorate the properties of titanium, its hardness and strength increase, and its plasticity decreases significantly.
For example, during the welding process of titanium, if the inert gas protection is not good, the dosage of oxygen, nitrogen, and carbon in the weld will increase, causing the strength and hardness of the weld metal to increase and the plasticity to decrease drastically. Therefore, when designing titanium equipment, its structure must be simple to reduce stress concentration on the weld, facilitate cleaning of the surface near the weld, and provide the use of inert gas.
To protect the conditions for the back and front of the weld, the long-term use temperature of equipment made of industrial pure titanium and certain titanium alloys should not exceed 350°C, and short-term and intermittent use should also be below 400°C.
