What is hydrogen embrittlement and how can we prevent it?

In one line

The rule

Hydrogen embrittlement is the process where metals, especially steel, become brittle and crack due to the absorption and diffusion of hydrogen atoms into their structure.

There is no single formula, but the key idea is:

• Hydrogen atoms enter the metal → They make it brittle (easy to break).

Let's understand it simply

Imagine you have a fresh roti. It’s soft and bends easily. Now, imagine tiny grains of sand get inside the dough before you cook it. When you try to fold the roti, it cracks and breaks where the sand is.

Hydrogen embrittlement is like that. Metals, like steel, are usually strong and bendy. But when tiny hydrogen atoms sneak inside, they act like sand in the roti. The metal becomes weak and can break suddenly, even if it looks fine from the outside.

How it works

1. Hydrogen atoms are introduced: Hydrogen gets into the metal during processes like welding, corrosion, or even from the environment.
2. Hydrogen diffuses: The tiny hydrogen atoms move inside the metal’s crystal structure (the way atoms are arranged inside the metal).
3. Hydrogen collects at weak spots: Hydrogen gathers at places where the metal is already weak, like cracks, grain boundaries, or defects.
4. Pressure builds up: The hydrogen atoms combine to form hydrogen molecules (H₂), which are bigger and create pressure inside the metal.
5. Cracks form and grow: The pressure and weakness cause the metal to crack and break, sometimes suddenly, even under normal loads.

The story behind it

Hydrogen embrittlement was first noticed in the 19th century when steel parts in bridges and ships started failing unexpectedly. Scientists like W.H. Johnson studied it in the early 1900s. They found that hydrogen, even in tiny amounts, could make strong metals brittle. This was a big problem in World War II, when steel ships cracked in cold seas. The problem led to new ways of making and testing metals.

Where you see it in real life

• Welding steel pipes: During welding, hydrogen from moisture or oil can enter the metal, making the welded joint weak.
• Pressure cookers: If the steel is poor quality and exposed to hydrogen (from acids or cleaning agents), it can crack.
• Petrol pumps: Pipelines carrying hydrogen gas or petrol can develop leaks due to embrittlement.
• Automobile parts: Car springs or gears can snap if hydrogen gets in during manufacturing or use.
• Bridges and buildings: Steel structures exposed to acid rain or pollution can suffer from embrittlement over time.
• Hydrogen fuel cells: Tanks and pipes storing hydrogen gas must be made from special materials to prevent cracking.

Why it matters

• Safety: Cracks from embrittlement can cause sudden failures in bridges, pressure vessels, or pipelines, leading to accidents.
• Industry: Factories, oil refineries, and power plants use metals that must resist embrittlement to avoid costly breakdowns.
• Transport: Trains, cars, and airplanes use high-strength steel that must be protected from hydrogen damage.
• New technology: As we move to hydrogen-powered vehicles, preventing embrittlement is crucial for safe storage and transport.

Worked example

Let’s say a steel rod is used in a bridge. During welding, some moisture is present, releasing hydrogen.

Given: Steel rod, welded in damp conditions
Step 1: Welding releases hydrogen from moisture
Step 2: Hydrogen atoms enter the steel’s structure
Step 3: Over time, hydrogen collects at weak spots
Step 4: Cracks start forming without warning
Step 5: The rod suddenly breaks under normal weight

How can we prevent it?

1. Use dry, clean materials: Remove moisture, oil, and dirt before welding or processing metals.
2. Bake (heat-treat) the metal: Heating steel after welding drives out hydrogen atoms.
3. Use low-hydrogen welding rods: These special rods produce less hydrogen during welding.
4. Choose resistant alloys: Use metals like stainless steel or add elements (like nickel) that resist embrittlement.
5. Protective coatings: Paint or coat the metal to stop hydrogen from entering.
6. Control the environment: Avoid exposing metals to acids, moisture, or hydrogen-rich gases.

Common mistakes

• Thinking only old metals are affected: Even new, shiny metals can suffer if hydrogen gets in.
• Ignoring small cracks: Tiny cracks can quickly grow and cause big failures.
• Using the wrong welding rods: Ordinary rods can introduce more hydrogen; always use low-hydrogen types for critical jobs.
• Not drying materials: Skipping the drying step before welding lets in more hydrogen.

Remember it

Hydrogen embrittlement: tiny hydrogen sneaks in, big cracks come out. Keep metal clean, dry, and protected.