Comparison of 316L and 316H Stainless Steel: Low-Carbon Corrosion-Resistant vs High-Carbon High-Temperature Grade

316L and 316H are two modified grades of 316 with opposite carbon content orientations: 316L is low-carbon, focusing on corrosion resistance and weldability; 316H is high-carbon, focusing on high-temperature creep strength. The two are applicable to completely different scenarios, with clear boundaries in corrosion resistance and high-temperature performance requirements.

Core Parameter Comparison

Parameter	316L Stainless Steel	316H Stainless Steel
Chemical Composition (wt%)	C≤0.03, Cr=16.00-18.00, Ni=10.00-14.00, Mo=2.00-3.00, Fe=Balance	C=0.04-0.10, Cr=16.00-18.00, Ni=10.00-14.00, Mo=2.00-3.00, Fe=Balance
Mechanical Properties (Annealed)	Tensile Strength ≥485MPa, Yield Strength ≥170MPa, Elongation ≥40%, Hardness ≤217HB	Tensile Strength ≥515MPa, Yield Strength ≥205MPa, Elongation ≥40%, Hardness ≤217HB
Service Temperature	-196℃ to 870℃ (continuous service)	500℃ to 870℃ (continuous service)
Equivalent Grades	SUS316L (JIS), EN 1.4404, UNS S31603	SUS316H (JIS), EN 1.4407, UNS S31609

Key Performance Differences: 1. Corrosion resistance: 316L has excellent intergranular corrosion resistance, no post-weld heat treatment required; 316H is prone to intergranular corrosion if welding heat input is not controlled. 2. High-temperature strength: 316H has higher creep strength than 316L at 500-870℃, creep rate 1/4 of 316L at 600℃. 3. Low-temperature performance: 316L has better low-temperature toughness, suitable for ultra-low temperature environments; 316H is not recommended for low-temperature long-term service. 4. Weldability: 316L has better weldability, wider application in welding-intensive components.

Applicable Scenario Distinction: 316L is suitable for harsh corrosion environments and welding-intensive components, such as marine engineering, seawater desalination equipment, chemical reaction kettles (chloride-containing media), and low-temperature storage tanks. 316H is suitable for high-temperature stress-bearing components in corrosive environments, such as thermal power plant boiler tubes (coastal areas), high-temperature chemical reactor internals, and offshore platform high-temperature pipelines.

Practical Q&A

Q1: Can 316L replace 316H in high-temperature applications? A1: No. 316L's low carbon content leads to poor high-temperature creep strength; at 700℃, its creep rupture life is only 1/2 of 316H, which cannot meet the strength requirements of high-temperature stress-bearing components.

Q2: Can 316H be used in seawater environments? A2: It can be used in marine atmospheric environments, but not recommended for long-term immersion in seawater; 316L has better seawater corrosion resistance, with annual corrosion rate ≤0.005mm.

Q3: What is the cost difference between 316L and 316H? A3: 316L is 5-8% more expensive than 316H, due to stricter carbon content control and higher nickel content; 316H is more cost-effective for high-temperature stress-bearing components.

Q4: What welding materials are used for 316L and 316H? A4: 316L matches ER316L welding wire, 316H matches ER316H welding wire; mixing use will reduce weld performance (e.g., ER316L wire reduces 316H weld creep strength by 30%).

Q5: How to select between 316L and 316H? A5: Choose 316L if corrosion resistance (chloride ions, weak acid) and weldability are the main requirements; choose 316H if high-temperature (500-870℃) creep strength is the core requirement and the environment is slightly corrosive.