Stainless Steel 316H

Stainless Steel 316H is a high-carbon (0.04–0.10%) variant of 316, designed to enhance high-temperature strength and creep resistance. Higher carbon forms more chromium carbides (without stabilization), making it suitable for 600–800°C non-welded parts like heat exchanger tubes.

Chemical Composition (Key, % ASTM A240): C0.04–0.10; Cr16.0–18.0; Ni10.0–14.0; Mo2.0–3.0; Mn≤2.0

Mechanical Properties (Annealed): Tensile Strength≥550MPa; Yield Strength≥220MPa; Elongation≥35%; Hardness≤235HB

Performance Advantages: Higher high-temp strength vs. 316; Mo-enhanced chloride resistance; good creep resistance at 600–800°C.

Applications: Non-welded heat exchangers, petrochemical piping, boiler tubes.

Equivalent Grades: EN1.4408, JIS SUS316H, DIN X10CrNiMo17-12-2

Comparison with 316: 316H retains 85% yield strength at 700°C (316 loses 20%); but prone to weld corrosion (use 316Ti for welded parts).

FAQs

Why is 316H stronger at high temps than 316? 0.04–0.10% carbon forms more chromium carbides than standard 316 (C≤0.08%). These carbides pin grain boundaries, slowing atomic movement and creep at 600–800°C. At 700°C, 316H's yield strength is 220MPa (316 is 205MPa), making it better for load-bearing high-heat parts. The carbides reinforce the structure without sacrificing Mo's chloride resistance.

 

Is 316H suitable for welded applications? No-higher carbon increases intergranular corrosion risk in welds. When welded, 316H's HAZ heats to 425–815°C, forming chromium carbides that deplete Cr and cause corrosion. Unlike 316Ti (titanium-stabilized), 316H lacks a carbon binder, so post-weld annealing (1010–1120°C) is required, adding costs. Use 316Ti for welded parts; 316H for non-welded components.

 

How does 316H perform in chloride environments? Its 2.0–3.0% Mo provides excellent pitting resistance in saltwater and brines, similar to 316. It suits coastal power plant heat exchangers and petrochemical piping (chloride-rich fluids). But avoid marine welded parts-corrosion risks are high without stabilization. 316H balances chloride resistance and high-temp strength for non-welded uses.

What heat treatment is needed for 316H? Anneal at 1010–1120°C (30–60 mins/25mm) to relieve work hardening and form uniform carbides. Water quench to prevent excessive carbide precipitation (causes brittleness). Welded parts require post-weld annealing to dissolve chromium carbides and restore corrosion resistance-critical for avoiding premature failure.

 

When to choose 316H over 316Ti? 316H is cheaper and stronger at 600–800°C for non-welded parts (heat exchangers). 316Ti is needed for welded components (no post-weld treatment) or marine use (titanium stabilization prevents corrosion). 316H suits static, non-welded high-heat apps; 316Ti for welded/chloride-rich scenarios.