What is 304H stainless steel:The Ultimate Guide

304H Stainless Steel Equivalent

304H stainless steel appears in many global material systems, which helps engineers match specifications during purchasing, inspection, and CNC machining.

Standard System	Country or Region	Equivalent Designation
UNS	United States	S30409
ASTM	United States	ASTM 304H
ASME	United States	SA-240 / SA-312 304H
EN	Europe	1.4948
DIN	Germany	X6CrNi18-10 (High-carbon variant)
JIS	Japan	SUS304H
GB	China	06Cr19Ni10H

304H Stainless Steel Compositions

The 304H stainless steel composition features a higher carbon content than standard 304. This increased carbon is the key factor that boosts high-temperature strength and improves creep resistance. The alloy also contains chromium, nickel, manganese, The table below shows the key alloying elements commonly found in 304H stainless steel.

Element	Typical Content Range
Carbon	0.04–0.10
Chromium	18.0–20.0
Nickel	8.0–11.0
Manganese	Up to 2.0
Silicon	Up to 0.75
Phosphorus	Up to 0.045
Sulfur	Up to 0.030
Nitrogen	Up to 0.10
Iron	Balance

304H Stainless Steel Properties

This section provides an overview of how 304H performs in strength, physical behavior, corrosion resistance, and high-temperature conditions, offering a clear snapshot of its overall material capabilities.

304H Stainless Steel Mechanical Properties

304H stainless steel properties offer strong tensile performance, reliable yield strength, and stable behavior under long-term heat exposure. These traits help CNC-machined parts maintain accuracy and strength when exposed to pressure, vibration, and thermal cycling. The table below shows the typical mechanical properties of 304H stainless steel used in engineering evaluation.

Property	Condition or Temper	Test Temperature	Typical Value or Range Metric	Typical Value or Range Imperial	Reference Standard
Tensile Strength	Annealed	Room Temperature	520 to 750 MPa	75 to 109 ksi	ASTM E8
Yield Strength 0.2 percent offset	Annealed	Room Temperature	205 to 310 MPa	30 to 45 ksi	ASTM E8
Elongation	Annealed	Room Temperature	40 percent minimum	40 percent minimum	ASTM E8
Hardness Rockwell B	Annealed	Room Temperature	70 to 90 HRB	70 to 90 HRB	ASTM E18
Impact Strength Charpy at 20°C	Annealed	20°C	40 J minimum	29.5 ft lbf	ASTM E23

304H Stainless Steel Physical Properties

The physical behavior of 304H stainless steel properties supports stable performance in high-temperature and high-pressure systems. Its density, thermal expansion rate, and conductivity help CNC-machined parts maintain precision even when exposed to repeated heating and cooling cycles.The table below shows the main physical properties of 304H stainless steel.

Property	Condition or Temperature	Value Metric	Value Imperial
Density	Room Temperature	7.93 g/cm³	0.286 lb/in³
Melting Point or Range	—	1400 to 1450 °C	2552 to 2642 °F
Thermal Conductivity	Room Temperature	16.2 W/m·K	112 BTU·in/h·ft²·°F
Specific Heat Capacity	Room Temperature	500 J/kg·K	0.12 BTU/lb·°F
Electrical Resistivity	Room Temperature	0.72 µΩ·m	0.72 µΩ·in
Coefficient of Thermal Expansion	Room Temperature	16.0 x 10⁻⁶/K	8.9 x 10⁻⁶/°F

304H Stainless Steel Corrosion Resistance

304H stainless steel provides reliable corrosion resistance, but its performance changes depending on the specific chemical environment and temperature. High-chloride media still pose a pitting risk, while mild organic acids and seawater conditions are generally well-tolerated.The table below summarizes how 304H stainless steel performs in common corrosive environments.

Corrosive Agent	Concentration (%)	Temperature (°C / °F)	Resistance Rating	Notes
Chlorides	3–5%	20–60°C / 68–140°F	Fair	Risk of pitting
Sulfuric Acid	10%	20–40°C / 68–104°F	Poor	Not recommended
Acetic Acid	10%	20–60°C / 68–140°F	Good	Moderate resistance
Sea Water	—	Ambient	Good	Suitable for marine environments

304H Stainless Steel Heat Resistance

304H stainless steel delivers dependable performance in high-temperature environments where dimensional stability and oxidation resistance are critical. Its higher carbon content strengthens the alloy against creep, allowing components such as heater tubes, boiler sections, and high-temperature manifolds to perform reliably under continuous thermal loads.The table below summarizes the key heat-resistance limits of 304H stainless steel.

Property or Limit	Temperature °C	Temperature °F	Remarks
Max Continuous Service Temperature	870	1600	Suitable for long exposure
Max Intermittent Service Temperature	925	1700	Supports short high-heat cycles
Scaling Temperature	800	1472	Resists oxidation before scale formation
Creep Strength Consideration	600	1112	Strength begins to decrease

304H Stainless Steel Fabrication Performance

This section explains how 304H stainless steel behaves during CNC machining, forming, welding, heat treatment, and finishing. It highlights key considerations to achieve precision, surface quality, and high-temperature stability.

CNC Machining

304H stainless steel machines well, but its higher carbon content can make maintaining precision challenging. Many engineers struggle with chip control, surface finish, and dimensional accuracy under high-temperature alloy conditions. Here’s a tip from VMT’s CNC processing experience: using sharper tooling with controlled feed rates ensures stable chip formation and consistent tolerances. Optimizing tool paths and spindle speeds also helps preserve surface quality, making it easier to achieve precision parts that can withstand long-term high-heat service.

Cold Working

Cold forming is moderate due to increased work-hardening. Intermediate annealing may be necessary to relieve stress and prevent cracking during bending, rolling, or other cold processes.

Hot Working

Hot working performs excellently between 980°C and 1175°C. Proper cooling after hot-forming prevents carbide precipitation and maintains corrosion resistance.

Heat Treatment

Annealing improves ductility and relieves internal stresses. Full anneal at 1050–1100°C followed by rapid cooling enhances formability, though 304H cannot be hardened by conventional heat treatment.

Welding

Welding 304H stainless steel is feasible using TIG, MIG, or SMAW. Controlled heat input minimizes carbide precipitation, and post-weld annealing may be needed for parts exposed to high temperatures.

Forming

304H can be bent, rolled, or deep-drawn, but higher carbon increases spring-back. Tooling and pressure adjustments help achieve precise shapes in CNC-fabricated components.

Surface Finish

The alloy achieves smooth, bright surfaces through grinding, polishing, or CNC machining. Its stability under heat and stress ensures a consistent finish for critical applications.

304H Stainless Steel Application

304H stainless steel is ideal for high-temperature and high-pressure environments across multiple industries:

• Power Generation: Used in industrial boilers, superheaters, steam exhaust systems, cooling towers, and condensers, where long-term creep resistance is critical.
• Petroleum, Gas, & Chemical Processing: Common in heat exchangers, pressure vessels, refinery equipment, and pipelines, providing reliable strength under thermal stress.
• High-Temperature Equipment: Applied to high-temperature piping, furnace components, pressure valves, and flanges that must withstand continuous heat exposure.
• Aerospace: Selected for certain engine components that require both high-temperature stability and structural integrity.

304H Stainless Steel Common Forms

• 304H Stainless Steel Round Bar
• 304H Stainless Steel Plate
• 304H Stainless Steel Sheet
• 304H Stainless Steel Pipe
• 304H Stainless Steel Tube
• 304H Stainless Steel Coil
• 304H Stainless Steel Wire
• 304H Stainless Steel Strip

304H Stainless Steel Price

The price of 304H stainless steel depends on material form, dimensions, market fluctuations in nickel, chromium, and iron, order quantity, and delivery location. Plates, sheets, pipes, and round bars have different production costs, and larger orders or nearby delivery locations can lower the unit price. High-precision or specialty items, such as seamless tubing, also affect cost due to manufacturing complexity and dimensional tolerances.

The table below shows typical market price examples for 304H stainless steel as of December 2025.Prices may change due to market fluctuations. For the latest price quote, please contact VMT for a free quote.

Form	Price Range
Sheets / Plates	~$1,100 – $3,000+ per ton (cold-rolled, hot-rolled)
Bars / Rods (Square, Hex, Flat)	~$2,100 – $2,800+ per metric ton
Tubes / Pipes	~$44,000 – $45,500+ per ton (welded/seamless specialty), or $11 – $20+ per meter depending on size
General / Per kg	~$2.50 – $60+ per kg, depending on form

304H vs 304L Stainless Steel

304H vs 304L mainly differs in carbon content. 304H has higher carbon, which improves high-temperature strength and creep resistance, while 304L has lower carbon to reduce carbide precipitation and improve weldability. Both share similar corrosion resistance and general mechanical properties at room temperature, but 304H performs better under continuous high-heat service, making it ideal for boilers, superheaters, and high-temperature piping.

304H vs 304 Stainless Steel

304H vs 304 differs primarily in carbon content. 304H contains higher carbon, which enhances strength and creep resistance at elevated temperatures, while standard 304 is optimized for general corrosion resistance and ease of fabrication at room temperature. Both grades have similar chromium and nickel levels, providing good overall corrosion resistance, but 304H is preferred for long-term high-temperature service, such as boilers, superheater tubes, and high-heat CNC-machined components.

VMT Case: Challenging in 304H Stainless Steel CNC Machining 

A client from Germany’s power generation industry needed 304H stainless steel components for a high-temperature boiler system. They faced challenges with CNC machining precision, surface finish, and ensuring the parts could withstand continuous high-heat service. Maintaining tight tolerances while avoiding warping or stress cracking was critical.

VMT Solution and Steps:

• Material Selection: Chose the optimal 304H stainless steel form to ensure high-temperature strength, creep resistance, and machinability for precision CNC parts.
• CNC Machining Optimization: Adjusted tooling, spindle speeds, and feed rates to achieve tight tolerances, stable chip formation, and superior surface finish.
• Surface Treatment Control: Applied polishing, finishing, and inspection procedures to maintain smooth, high-quality surfaces suitable for high-heat service.
• Quality Assurance: Used high-precision measurement instruments and implemented CPK ≥68 standards to guarantee critical dimensions met specifications.
• Welding and Heat Treatment: Controlled welding heat input and applied proper annealing to preserve corrosion resistance, strength, and dimensional stability.

The client successfully received components that met high-temperature strength requirements, precise tolerances, and smooth finishes. Parts performed reliably in the boiler system, and production schedules were maintained. For similar high-performance CNC machining needs, contact us to explore solutions and best practices.

Conclusion

304H stainless steel offers a combination of high carbon strength, excellent creep resistance, reliable corrosion performance, and stable behavior at elevated temperatures. it suitable for boilers, heat exchangers, high-temperature piping, and precision CNC components. Understanding its mechanical, physical, and fabrication properties ensures engineers select the right material for high-heat and high-stress applications.