In-depth analysis and technology promotion of porosity problems in laser-welded stainless steel pipe
Posted by： Hangao Time：11/3/2025 9:52:02 AM
In modern stainless steel welded pipe manufacturing workshops, laser welding technology, with its advantages of high efficiency, precision, and automation, has become the mainstream choice in the industry. However, even the most advanced laser welding machines cannot completely avoid the generation of porosity defects. Although small, porosity can become an "invisible killer" of welded pipe performance and lifespan, posing a severe challenge to product quality and customer trust.
This article will analyze the causes, types, and hazards of porosity defects in laser-welded stainless steel pipes in conjunction with actual production scenarios, and share systematic prevention and control technologies to help enterprises improve welding quality and ensure product stability and reliability.
I. The Nature and Classification of Porosity Defects
1.1 What are Porosity Defects?
Porosity refers to tiny voids formed inside or on the surface of the weld, mainly caused by gas failing to escape in time during the welding process. It directly affects the density and mechanical properties of the weld and is a common and critical quality problem in laser-welded stainless steel pipes.
1.2 Main Types of Porosity
Metallurgical Porosity: Mainly caused by hydrogen gas, sources include moisture, oil, oxide film on the material surface, and the hydrogen content of the material itself.
Process-related porosity: During laser deep penetration welding, the keyhole is unstable, causing the molten metal to collapse and form bubbles. These bubbles fail to escape before solidification and remain.
II. Multidimensional Analysis of Porosity Causes
2.1 Material Factors
The base metal or welding wire surface contains impurities such as moisture, oil, and oxide films.
The material itself has a high hydrogen content, easily releasing gas.
2.2 Influence of Process Parameters
Improper laser power setting (too high or too low) leads to an unstable molten pool.
Mismatched welding speed affects the gas escape time from the molten pool.
Focus position deviation affects the penetration depth and molten pool morphology.
2.3 Shielding Gas Quality and Flow Rate
Insufficient shielding gas purity, excessive oxygen content.
Unstable gas flow rate causes air to be entrained in the molten pool.
2.4 Cooling Rate and Solidification Process
The molten pool solidifies too quickly, preventing bubbles from escaping.
III. Hazards of Porosity Defects
Reduced weld tensile and fatigue strength, affecting structural safety.
Destroys weld density, reducing corrosion resistance.
Becomes a source of crack initiation, shortening the service life of the welded pipe.
IV. System Prevention and Control Strategies
4.1 Pre-welding Materials and Surface Treatment
Thoroughly clean the welding surface to remove oil, moisture, and oxide film.
Select low-hydrogen-content, high-purity stainless steel.
4.2 Process Parameter Optimization
Precisely control laser power, welding speed, and focal point position to ensure a stable molten pool.
Employ real-time monitoring technology to dynamically adjust welding parameters.
4.3 Shielding Gas Management
Use high-purity argon or helium to ensure gas purity.
Stable gas flow rate to prevent air entrapment.
4.4 Cooling and Heat Treatment Control
Appropriately control the cooling rate to prolong bubble escape time.
Use preheating or post-heating processes when necessary to improve weld microstructure.
V. Conclusion
Although the porosity issue in laser-welded stainless steel pipes may seem minor, it is crucial to the core quality and safety of the product. Through scientific material selection, strict process control, and comprehensive protective measures, companies can not only effectively reduce the porosity defect rate but also improve the overall welding quality and enhance market competitiveness.
We look forward to Guangdong Henkel Technology Co., Ltd. working hand in hand with industry partners to promote the innovation and application of laser welding technology and create higher-quality stainless steel welded pipe products.
