Correction process for internal defects of titanium alloy pipes and titanium pipe welds

The internal shortcomings of Titanium Alloy Seamless Rectangular Tube welds, lack of penetration, refers to a defect in which the workpiece and the weld metal or the part between the weld layers are not fused. Incomplete penetration weakens the welding seam working section, constitutes severe stress concentration, greatly reduces the joint strength, and it often becomes the source of weld cracking. There is non-metallic slag in the slag inclusion weld, which is called slag inclusion. The slag inclusion reduces the working section of the weld, and constitutes a stress concentration, which will reduce the strength and impact toughness of the weld.

When the pore weld metal absorbs too much gas (such as H2) or the gas (such as CO) generated by the internal metallurgical reaction of the molten pool at high temperature, it is too late to be discharged when the molten pool is cooled and condensed and is formed inside or on the outside of the weld Holes are pores. The existence of pores reduces the useful working section of the weld and reduces the mechanical strength of the joint. If there are penetrating or continuous pores, it will severely affect the tightness of the weldment. During or after welding, cracks in the metal part of the welded joint area are called cracks. Cracks can occur in the weld, and can also occur in the heat-affected zone on both sides of the weld. Sometimes it occurs on the outside of the metal, and sometimes inside the metal.

Usually, according to the mechanism of crack occurrence, it can be divided into two types: hot crack and cold crack. Thermal cracks occur during the crystallization process from liquid to solid in the weld metal, and most of them occur in the weld metal. The main reason for its occurrence is the presence of low melting point substances (such as FeS, melting point 1193°C) in the weld, which weakens the contact between the grains. When subjected to greater welding stress effects, it simply causes cracks between the grains. . When the weldment and electrode contain a lot of impurities such as S and Cu, thermal cracking simply occurs. Thermal cracks have the characteristic of spreading along the grain boundary. When the crack penetrates the surface and communicates with the outside, it has a significant hydrogenation tendency. Cold cracks occur during the cooling process after welding, mostly on the base metal or the fusion line between the base metal and the weld. The primary reason for this is that the quenching arrangement is formed in the heat-affected zone of the weld. Under the effect of high stress, it causes cracks in the crystal grains. When welding easy-quenchable ASTM B861 25*1.2mm Titanium Tube For Chemical with high carbon content or more alloying elements, The most prone to cold cracks. Too much hydrogen melted into the weld can also cause cold cracks. Cracks are one of the riskiest shortcomings. In addition to reducing the load-bearing section, severe stress accumulation will occur. During use, the cracks will gradually expand and eventually cause damage to the components. Therefore, such shortcomings are usually not allowed in the welding layout.