About the influence of used High Frequency Tube Mills welded tube billet defects on the quality of welded pipes

Publish Time: 2025-03-18

Used High Frequency Tube Mills is an advanced equipment that cold bends strip steel into round billets through roller forming and forms welds through high-frequency induction heating. It is capable of producing round tubes and square and rectangular tubes of various standard specifications. However, during the production process, the defects of welded tube billets will directly affect the quality and performance of the final product. Therefore, it is crucial to understand the types of welded tube billet defects and their effects in order to take effective control measures to improve the quality of welded pipes.

1. Classification of defects in welded pipe billets

According to the nature of defects in welded pipe billets, they can be divided into dominant defects and invisible defects. Dominant defects are those that can be identified visually alone, such as cracked edges, broken edges, serrations and scratches. Invisible defects require the help of certain detection methods to be discovered, including the chemical composition and mechanical properties of welded pipe billets.

1. Dominant defects

1.1 Cracked edges

Cracked edges refer to defects in the edge of the pipe billet with cracks or cracks. This defect usually occurs during the forming process due to the longitudinal tensile stress on the edge of the pipe billet. Its hazards are mainly reflected in:

During the forming process, cracks will expand under the action of longitudinal tensile stress, resulting in the inability to ensure the density and strength of the weld.

The weld cannot withstand deformation operations such as bending, flaring, flattening and flanging in subsequent processing.

1.2 Edge Breakage

Edge breakage refers to the phenomenon of damage to the edge of the tube billet. This defect will cause discontinuity of the weld and affect the overall quality of the welded pipe. The causes of edge breakage may include mechanical damage or improper operation during processing.

1.3 Sawtooth

Sawtooth refers to the bulge on the outside of the edge of the tube billet, which is common in hot-rolled tube billets. The main reasons for the occurrence of sawtooth include local deformation caused by uneven contact between the edge of the tube billet and the rolling mill during hot rolling. The presence of sawtooth will affect the flatness and uniformity of the weld, and thus affect the quality of the welded pipe.

1.4 Scratches

Scratches refer to linear marks or depressions on the surface of the tube billet. These scratches may be caused by mechanical friction, wear of processing tools or other external factors. Scratches not only affect the appearance quality of welded pipes, but may also cause stress concentration at the weld, reducing the strength and durability of welded pipes.

2. Invisible defects

2.1 Unqualified chemical composition

The chemical composition of welded pipe billets has an important influence on their performance. If the chemical composition does not meet the standard, it may cause corrosion, fatigue and other problems in the use of welded pipes. For example, excessive content of impurities such as sulfur and phosphorus will increase the brittleness of the weld and reduce the toughness and crack resistance of the welded pipe.

2.2 Unqualified mechanical properties

The mechanical properties of welded pipe billets include yield strength, tensile strength, elongation and other indicators. If these performance indicators do not meet the requirements, the welded pipe may break, deform and other problems in actual use, affecting its service life and safety.

2. The impact of welded pipe billet defects on the quality of welded pipes

The explicit and invisible defects of welded pipe billets will have many impacts on the production process of welded pipes and the quality of the final product. The following is a specific analysis:

1. Impact on weld quality

The defects of welded pipe billets will directly affect the stability of the welding process and the quality of the weld. For example, cracked edges and broken edges will cause discontinuity of the weld, affecting the density and strength of the weld. Sawtooth and scratches will cause stress concentration at the weld, increasing the risk of weld cracking. In addition, welded pipe blanks with unqualified chemical composition will cause unstable physical and chemical properties of weld metal, further affecting the quality of the weld.

2. Impact on the dimensional accuracy of welded pipes

Explicit defects such as cracked edges, broken edges and serrations will cause increased dimensional deviation of welded pipes and affect their geometric dimensional accuracy. This is unacceptable for some precision applications. For example, high-precision welded pipes used in building structures will affect the safety and stability of the overall structure if the dimensional accuracy does not meet the standard.

3. Impact on the surface quality of welded pipes

Explicit defects such as scratches will have a serious impact on the surface quality of welded pipes, making their surfaces rough and unsightly. This not only affects the market competitiveness of welded pipes, but may also cause other problems during subsequent processing and use, such as poor coating adhesion.

3. How to reduce the impact of welded pipe billet defects on welded pipe quality

In order to reduce the impact of welded pipe billet defects on welded pipe quality, we can start from the following aspects:

1. Raw material selection and control

Selecting high-quality raw materials is the basis for ensuring the quality of welded pipes. The chemical composition and mechanical properties of welded pipe billets should be strictly controlled to ensure that they meet relevant standards and specifications. At the same time, when purchasing raw materials, reputable suppliers should be selected and strict inspection and acceptance should be carried out.

2. Production process optimization

In the production process, advanced process technology and equipment should be used to strictly control the quality of each production link. For example, during the forming process, the bottom line height of the roller and the bottom line of rolling should be adjusted to avoid problems such as crushing and cracking. During the welding process, parameters such as input heat, extrusion pressure, opening angle, welding speed, etc. should be reasonably controlled to ensure stable and reliable weld quality.

3. Quality inspection and control

Strengthening quality inspection and control is an important means to ensure the quality of welded pipes. Regular quality inspection and testing should be carried out on welded pipe billets to promptly discover and deal with existing defects and problems. At the same time, quality control points should be set up during the production process to monitor and manage key processes to ensure that product quality meets standard requirements.

Used High Frequency Tube Mills The defects of welded tube blanks have an important impact on the quality of welded pipes. Only by fully understanding the types of these defects and their influencing mechanisms and taking effective control measures can we ensure the production of high-quality and high-performance welded pipe products.