Cracks in laser-welded stainless steel pipes
Posted by： Hangao Time：11/3/2025 9:11:59 AM
Cracks in Laser-Welded Stainless Steel Pipes
Q1: Why are laser-welded stainless steel pipes prone to cracking?
A1: There are three main reasons:
* Metallurgical factors: During weld solidification, low-melting-point impurities (such as sulfur and phosphorus) accumulate at grain boundaries, leading to grain boundary brittleness.
* Mechanical factors: Laser welding involves concentrated heat input and rapid cooling, resulting in high weld shrinkage stress.
* Process factors: Improper welding parameters, insufficient shielding gas, or incomplete surface cleaning.
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Q2: What types of cracks are there?
A2: Common crack types include:
* Solidification cracks: Appearing at the weld centerline, formed by tearing of the liquid film at grain boundaries.
* Liquefaction cracks: Located near the fusion line, caused by localized melting of grain boundaries in the heat-affected zone.
* Reheat cracks: Occur during post-weld thermal cycling or heat treatment.
* Heat-affected zone cracks: Caused by excessively rapid cooling or hydrogen embrittlement.
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Q3: What hazards do cracks cause? A3:
Reduced weld strength, affecting pressure resistance
Destroys density, reducing corrosion resistance
Becomes a stress concentration point, shortening service life
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Q4: How to prevent crack formation?
A4:
Materials: Select high-purity stainless steel to reduce impurity content
Process: Properly control laser power, welding speed, and focal point position
Protection: Use high-purity argon/helium gas to avoid oxidation and hydrogen embrittlement
Heat treatment: Perform preheating and post-heat treatment when necessary to reduce residual stress
Pre-welding preparation: Thoroughly clean the workpiece surface to remove oil, moisture, and oxides
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Q5: How to quickly assess crack risk on-site?
A5:
Observe the weld surface for continuous fine lines or hidden cracks.
Check if the welding parameters are too high or too low.
Pay attention to the humidity of the welding environment and the purity of the shielding gas.
For thick-walled pipes or high-strength steel, focus on the heat-affected zone.
---
Summary: Although cracks are common in laser-welded stainless steel pipes, the risk can be significantly reduced and weld quality and service life ensured through measures such as material purification, process optimization, gas protection, and heat treatment.
---
Q1: Why are laser-welded stainless steel pipes prone to cracking?
A1: There are three main reasons:
* Metallurgical factors: During weld solidification, low-melting-point impurities (such as sulfur and phosphorus) accumulate at grain boundaries, leading to grain boundary brittleness.
* Mechanical factors: Laser welding involves concentrated heat input and rapid cooling, resulting in high weld shrinkage stress.
* Process factors: Improper welding parameters, insufficient shielding gas, or incomplete surface cleaning.
---
Q2: What types of cracks are there?
A2: Common crack types include:
* Solidification cracks: Appearing at the weld centerline, formed by tearing of the liquid film at grain boundaries.
* Liquefaction cracks: Located near the fusion line, caused by localized melting of grain boundaries in the heat-affected zone.
* Reheat cracks: Occur during post-weld thermal cycling or heat treatment.
* Heat-affected zone cracks: Caused by excessively rapid cooling or hydrogen embrittlement.
---
Q3: What hazards do cracks cause? A3:
Reduced weld strength, affecting pressure resistance
Destroys density, reducing corrosion resistance
Becomes a stress concentration point, shortening service life
---
Q4: How to prevent crack formation?
A4:
Materials: Select high-purity stainless steel to reduce impurity content
Process: Properly control laser power, welding speed, and focal point position
Protection: Use high-purity argon/helium gas to avoid oxidation and hydrogen embrittlement
Heat treatment: Perform preheating and post-heat treatment when necessary to reduce residual stress
Pre-welding preparation: Thoroughly clean the workpiece surface to remove oil, moisture, and oxides
---
Q5: How to quickly assess crack risk on-site?
A5:
Observe the weld surface for continuous fine lines or hidden cracks.
Check if the welding parameters are too high or too low.
Pay attention to the humidity of the welding environment and the purity of the shielding gas.
For thick-walled pipes or high-strength steel, focus on the heat-affected zone.
---
Summary: Although cracks are common in laser-welded stainless steel pipes, the risk can be significantly reduced and weld quality and service life ensured through measures such as material purification, process optimization, gas protection, and heat treatment.
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