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The Influence of Gas and Impurities on the Properties of Titanium and Titanium Alloy Welding

About welding technology
Titanium and titanium alloys have been widely used in aerospace, chemical, medical and other fields due to their unique physical and chemical properties. However, these materials face many challenges during the welding process, among which the effects of gases and impurities are particularly significant. This article will explore the effects of gases and impurities on the welding performance of titanium and titanium alloys from the perspective of gas and impurities.
1. The influence of gas on welding performance
The influence of gas on titanium and titanium alloys cannot be ignored during the welding process. Hydrogen, oxygen, and nitrogen are common gas elements in the welding process, which have a direct impact on the quality and performance of the weld.
Firstly, hydrogen is a key factor affecting the mechanical properties of titanium. During the welding process, hydrogen will enter the weld metal, forming sheet-like or needle like TiH2. This compound has lower strength and significantly reduces the impact performance of the weld. Therefore, controlling the hydrogen content in the weld seam is one of the important measures to improve welding quality.
Secondly, oxygen and nitrogen can also have a significant impact on the welding performance of titanium and titanium alloys. Oxygen can be present in titanium α Xianghe β The formation of interstitial solid phase in the phase leads to an increase in the hardness and strength of the weld, but a significant decrease in plasticity. Nitrogen, on the other hand, forms brittle and hard titanium nitride with titanium at high temperatures, further reducing the plasticity of the weld. To prevent these adverse effects, it is necessary to strictly control the oxygen and nitrogen content during the welding process.
2. The influence of impurities on welding performance
In addition to gas elements, impurities are also an important factor affecting the welding performance of titanium and titanium alloys. Carbon is one of the common impurities in titanium and titanium alloys. When the carbon content is high, it will lead to the formation of a network of TiC in the weld, significantly reducing the plasticity of the weld. In addition, impurities such as sulfur and phosphorus can also form low melting point eutectic substances during the welding process, increasing the risk of thermal cracking in the weld seam.
In order to reduce the impact of impurities on welding performance, it is necessary to strictly control the chemical composition of the base material and welding wire to ensure that the impurity content is within a reasonable range. At the same time, effective measures need to be taken during the welding process, such as selecting appropriate welding process parameters, preheating the welding area, etc., to reduce welding stress and crack generation.
3. Weld cracking and porosity issues
Cracks and pores are common defects in the welding process of titanium and titanium alloys. Cracks are mainly divided into two types: hot cracks and cold cracks. Due to the low impurity content in titanium and titanium alloys, the probability of hot cracking is relatively low. However, cold cracking is a key issue that requires special attention. This type of crack usually appears several hours or longer after welding, and is called a delayed crack. Research has shown that this type of crack is related to the diffusion of hydrogen during the welding process. To prevent the occurrence of cold cracks, it is necessary to reduce the hydrogen source in the welded joint, such as using vacuum annealing treatment and other methods.
Pores are another common welding defect, and their formation is mainly related to the influence of hydrogen. In order to prevent the formation of pores, it is necessary to ensure the purity of argon gas protection, thoroughly remove organic substances such as oil stains on the surface of welded parts and welding wires, control the flow and speed of argon gas, and select appropriate welding process parameters.
In summary
Gas and impurities have a significant impact on the welding performance of titanium and titanium alloys. In order to improve welding quality, it is necessary to strictly control the gas and impurity content during the welding process, and take effective measures to prevent the generation of cracks and pores. Only in this way can the excellent performance of titanium and titanium alloys be fully utilized, providing strong support for the development of various industries.

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