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What are the different material choices for water-cooled walls?

Release time:

2025/11/29

The selection of waterwall materials must take into account working temperature, corrosive environment, and mechanical load in a comprehensive manner. The main differences are as follows:

I. High-Temperature Resistance Requirements
T23 Steel: Specifically designed for ultra-supercritical and ultra-ultra-supercritical boilers, this steel can withstand long-term operating temperatures up to 600°C. Its high-temperature strength is enhanced through microalloying with W, V, and Nb.
T22 Steel: Suitable for subcritical boilers, with an upper temperature limit of approximately 580°C. Stability must be ensured through normalizing and tempering treatments.
Stainless steel—such as 304/316L—has a temperature resistance range of 200–400℃, but it tends to deform easily at high temperatures and is therefore often used in low-temperature corrosive environments.
II. Corrosion Resistance Requirements
Acidic Environment: To resist gases such as SO₂ and NOx, T23/T22 steel relies on an oxide film formed by its chromium-molybdenum alloy for protection. Stainless steels (such as 316L) exhibit even better resistance to both acidic and alkaline corrosion.
Alkaline Environment: TiN precipitates in T23 steel can strengthen grain boundaries and reduce the risk of alkali embrittlement.
III. Mechanical Strength and Welding Performance
Strength: The tensile strength of T23 steel is ≥415 MPa, and its yield strength is ≥205 MPa, both exceeding those of T22 steel.
Weldability: When the wall thickness of T23 steel is ≤8mm, post-weld heat treatment can be omitted (per DL/T 869-2012 standard), but preheating is required to prevent cold cracking. For T22 steel, post-weld heat treatment is mandatory to relieve residual stresses.
IV. Typical Application Scenarios
Supercritical boilers: T23 steel is preferred, balancing high-temperature strength and welding efficiency.
Conventional boilers: T22 steel offers better cost performance, but requires a stringent heat treatment process.
Corrosive media: Stainless steel (such as 316L) or titanium alloys are more suitable.

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The primary heat transfer mode of water-cooled walls is:

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