316H Stainless Steel: Corrosion-Resistant Champion For High-Temperature Corrosive Environments

316H is a high-carbon strengthened version of 316 (carbon content 0.04%-0.10%). Based on 316 containing molybdenum (2%-3%), it improves high-temperature creep strength through high carbon, combining excellent high-temperature corrosion resistance and structural stability. It is a core material for harsh high-temperature environments.

Core Parameters

Chemical Composition (wt%): C=0.04-0.10, Si≤1.00, Mn≤2.00, P≤0.045, S≤0.030, Cr=16.00-18.00, Ni=10.00-14.00, Mo=2.00-3.00, Fe=Balance

Mechanical Properties (Annealed): Tensile Strength ≥515MPa, Yield Strength ≥205MPa, Elongation ≥40%, Brinell Hardness ≤217HB

Service Temperature: 500℃ to 870℃ (continuous service)

Equivalent Grades: SUS316H (JIS), EN 1.4407 (EN), UNS S31609 (ASTM)

Performance Advantages: Molybdenum element makes the high-temperature pitting and crevice corrosion resistance 3 times higher than that of 304H; excellent corrosion resistance to sulfur-containing gas (SO₂) at 800℃; creep strength is equivalent to 304H, but service life is extended by 5-8 times under corrosive working conditions.

Typical Applications: Boiler components of thermal power plants in coastal areas, high-temperature chemical reactors (containing chlorine/sulfur media), high-temperature pipelines of offshore platforms, heating surfaces of waste incinerators, aircraft engine accessories.

Practical Q&A

Q1: What is the specific impact of molybdenum content on the high-temperature performance of 316H? A1: Molybdenum can refine grains, improve grain boundary strength at high temperatures, and form a stable MoO₃ oxide film, enhancing the barrier ability against chloride ions and sulfides. In a chlorine-containing environment at 700℃, the corrosion rate of 316H is only 1/10 of that of 304H.

Q2: How to match filler materials when welding 316H? A2: ER316H welding wire must be selected, whose carbon and molybdenum contents are consistent with the base metal to ensure high-temperature strength and corrosion resistance of the weld. Avoid using ER316L welding wire, which will reduce the creep strength of the weld by more than 30%.

Q3: How to select between 316H and 316Ti under high-temperature working conditions? A3: 316Ti (containing titanium) has stronger intergranular corrosion resistance, suitable for long-term static working conditions at 400-900℃; 316H has higher high-temperature creep strength, suitable for dynamic stress-bearing components (such as fan shafts, valve cores) at 500-870℃.

Q4: The cost of 316H is relatively high. Is there an alternative? A4: In non-strongly corrosive high-temperature environments (such as dry air), 304H can be used instead, reducing costs by 40%; in medium and low-temperature (≤500℃) corrosive environments, 316L can be used, reducing costs by 20%, but its high-temperature strength is insufficient.

Q5: How to test whether the high-temperature performance of 316H meets the standard? A5: The core test is the creep rupture test. Under the conditions of 650℃ and 100MPa stress, a rupture time ≥10,000 hours is considered qualified; at the same time, the Strauss test (intergranular corrosion test) is used to ensure post-weld corrosion resistance.