022Cr19Ni16Mo5N (GB/T 4237) Stainless Steel
022Cr19Ni16Mo5N (S31793) Stainless Steel: High Mo+N Austenitic Grade per GB/T 4237
Comprehensive data for 022Cr19Ni16Mo5N (S31793) austenitic stainless steel plate/coil under GB/T 4237, covering chemical composition, mechanical and physical properties, international equivalents, and application guidance.
Hot rolling, cold rolling, solution annealing, pickling, welding, forming
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022Cr19Ni16Mo5N Stainless Steel Introduction
022Cr19Ni16Mo5N (UNS S31793) is a nitrogen-enhanced high-molybdenum austenitic stainless steel designed for exceptional resistance to pitting, crevice corrosion, and chloride-induced stress corrosion cracking. The combination of approximately 4–5% molybdenum and 0.10–0.20% nitrogen significantly improves corrosion resistance over standard 317L grades, especially in acidic and halide-containing environments. It maintains a fully austenitic microstructure in the solution-annealed condition, offering good toughness, formability, and weldability. This grade is primarily supplied as hot-rolled plate and coil according to GB/T 4237, and is widely used in aggressive chemical processing, marine, pulp and paper, and flue gas desulfurization (FGD) systems.
022Cr19Ni16Mo5N Stainless Steel Chemical Composition
The chemical composition limits for 022Cr19Ni16Mo5N according to GB/T 4237-2015 are tightly controlled to ensure high pitting resistance equivalent to PREN ≥ 34. The alloy is characterized by a high molybdenum (4.0–5.0%) and nitrogen (0.10–0.20%) content, which strongly enhances corrosion properties and strength.
| Element | Standard Value (%) | Remarks |
|---|---|---|
| Carbon (C) | ≤0.030 | Low carbon for improved intergranular corrosion resistance |
| Silicon (Si) | ≤1.00 | Deoxidizing element |
| Manganese (Mn) | ≤2.00 | Austenite stabilizer |
| Phosphorus (P) | ≤0.045 | Impurity controlled |
| Sulfur (S) | ≤0.030 | Impurity controlled |
| Chromium (Cr) | 18.00–20.00 | Key for corrosion resistance |
| Nickel (Ni) | 15.00–17.00 | Austenite former, enhances ductility |
| Molybdenum (Mo) | 4.00–5.00 | Improves pitting and crevice corrosion resistance |
| Nitrogen (N) | 0.10–0.20 | Increases strength and pitting resistance |
022Cr19Ni16Mo5N Stainless Steel Thermal and Electrical Physical Properties
The following data represent typical physical properties for 022Cr19Ni16Mo5N (comparable to 317LMN) in the solution-annealed condition. These values are useful for design and simulation but are not specified in GB/T 4237; they are drawn from widely accepted materials databases.
| Property | Typical Value | Unit | Condition / Temperature |
|---|---|---|---|
| Density (ρ) | 8.0 | g/cm³ | At 20°C |
| Modulus of elasticity (E) | 200 | GPa | At 20°C |
| Shear modulus (G) | 77 | GPa | At 20°C |
| Poisson's ratio (ν) | 0.3 | - | At 20°C |
| Thermal expansion coefficient (α) | 16.5 | 10⁻⁶/K | 20–100°C |
| Thermal expansion coefficient (α) | 17.5 | 10⁻⁶/K | 20–300°C |
| Thermal expansion coefficient (α) | 18.0 | 10⁻⁶/K | 20–500°C |
| Thermal conductivity (λ) | 14 | W/(m·K) | At 100°C |
| Thermal conductivity (λ) | 16 | W/(m·K) | At 300°C |
| Thermal conductivity (λ) | 19 | W/(m·K) | At 500°C |
| Specific heat capacity (c) | 500 | J/(kg·K) | At 20°C |
| Electrical resistivity (ρ_e) | 0.82 | μΩ·m | At 20°C |
022Cr19Ni16Mo5N Stainless Steel Mechanical Properties
Mechanical property requirements for 022Cr19Ni16Mo5N hot-rolled plate/coil in the solution-annealed condition as per GB/T 4237-2015. Room temperature tensile and hardness values are guaranteed minimums; bend test ensures adequate formability.
| Property | Standard Requirement | Unit | Test Condition |
|---|---|---|---|
| 0.2% proof strength (Rp0.2) | ≥245 | MPa | Room temperature, transverse |
| 1% proof strength (Rp1.0) | ≥275 | MPa | Room temperature, transverse |
| Tensile strength (Rm) | ≥550 | MPa | Room temperature, transverse |
| Elongation after fracture (A) | ≥25 | % | Gauge length 50 mm, all thicknesses |
| Hardness (HBW) | ≤217 | - | As per standard conversion |
| Hardness (HRB) | ≤95 | - | As per standard conversion |
| Hardness (HV) | ≤220 | - | As per standard conversion |
| Bend test (180°) | No cracks | deg | Bend diameter d=2a for thickness ≤8 mm |
| Bend test (180°) | No cracks | deg | Bend diameter d=3a for thickness >8 mm |
022Cr19Ni16Mo5N Stainless Steel Exact Equivalent Standards and Substitutable Grades
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| China | GB/T 4237 | 022Cr19Ni16Mo5N (S31793) | Original specification grade |
| USA | ASTM A240/A240M | UNS S31726 (317LMN) | Closest international match; identical Cr, Mo, N ranges, Ni 13.5–17.5% |
| Europe | EN 10088-2 | X2CrNiMoN17-13-5 (1.4439) | Similar high-Mo+N grade, but with lower Ni (12.5–14.5) and Cr (16.5–18.5); verify for critical corrosion service |
| Japan | JIS G4304 | SUS317LN (S31753) | Approximate substitute; Mo range 3.0–4.0% (lower), N 0.10–0.22; may underperform in extreme pitting environments |
| International | ISO 15510 | X2CrNiMoN17-13-5 (4435-317-26-I) | Corresponds to the 4435-317-26-I designation; composition aligns closely with 317LMN |
022Cr19Ni16Mo5N Stainless Steel Application Introduction
022Cr19Ni16Mo5N is optimized for service in environments containing chlorides, organic acids, and sulfur-containing compounds at moderate temperatures. Its high molybdenum and nitrogen content provide PREN values typically above 34, making it suitable where 316L or 317L would suffer pitting or crevice attack. Typical product forms include hot-rolled plates and coils that are further fabricated into tanks, heat exchangers, and flue gas scrubbers. The material is readily welded with matching or over-alloyed fillers, and post-weld annealing is not usually required for corrosion resistance, although solution annealing restores full properties after heavy forming.
Product Applications: Pressure vessels and storage tanks per ASME or GB standards, Shell-and-tube heat exchangers and condensers, Rectangular or circular ductwork for FGD systems, Welded pipes and fittings for corrosive fluid transport, Structured packing and internals for chemical columns
Processed into products: Reactor vessels and agitators in chlor-alkali plants, Condenser tubes and tube sheets in seawater service, Pump impellers and shafts in sulfuric acid environments, Flue gas desulfurization spray headers and nozzles, Valve bodies and trim for high-chloride process streams, Evaporator bodies in the pulp and paper industry
Application industries: Chemical Processing (reactors, columns, piping for acids and chlorinated solvents), Oil & Gas (offshore topside equipment, seawater cooling systems), Marine Engineering (desalination plants, heat exchangers, pump bodies), Pulp & Paper (bleach plant washers, digesters, chemical recovery units), Power Generation (flue gas desulfurization absorbers, ducting, mist eliminators)
022Cr19Ni16Mo5N Stainless Steel Similar / Near-Equivalent Alternative Materials
| Country/Region | Standard | Grade | Remarks |
|---|---|---|---|
| China | GB/T 4237 | 022Cr19Ni13Mo3 (S31703) | 317L grade; lower Mo (3.0–4.0%), no nitrogen addition, lower strength and corrosion resistance |
| China | GB/T 4237 | 022Cr17Ni12Mo2N (S31653) | 316LN; Mo 2.0–3.0, N 0.10–0.16, significantly lower pitting resistance, suitable for less aggressive media |
| USA | ASTM A240 | UNS N08926 (6Mo super austenitic) | Higher Mo (6.0–7.0) and N, superior corrosion resistance but higher cost; alternative for severe chloride service |
| Europe | EN 10088-2 | X1CrNiMoCuN25-25-5 (1.4537) | Super austenitic, higher Ni, Cr, Mo; for extreme corrosion, but heavier and more expensive |
Notes:
- Heat treatment: Solution anneal at 1010–1150°C followed by rapid water or air cooling. Stress relief between 300–450°C may be applied, but avoid prolonged exposure at 600–900°C to prevent sigma phase embrittlement.
- Welding: Excellent weldability with GTAW, GMAW, SAW processes. Recommended filler metals: ER317LMN (AWS A5.9) or equivalent over-alloyed grades to maintain corrosion resistance. Post-weld heat treatment is generally not necessary.
- Forming: Good hot and cold formability; due to high work hardening rate, heavier gauge may require intermediate annealing. Cold bending radius should follow manufacturer recommendations.
- Corrosion properties: PREN (Pitting Resistance Equivalent Number) = %Cr + 3.3%Mo + 16%N ≈ 34–38, indicating excellent resistance in brackish and mildly acidic chloride media. Resists intergranular corrosion in as-welded condition due to low carbon content.
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