316H Stainless Steel (UNS S31609)

Stainless steel is wide range amalgamations of ferrous and other alloying agents. It is composed of iron, carbon and chromium. It has stable passive layer of chromium oxide which protects it against corrosive agents. It has vast benefits and famous peculiarity of resisting corrosion. Stainless steel is an ideal choice for outdoor structures, water, and high temperature uses.

Its benefits include corrosion and heat resistance, strength, ductility, formability and weldability. Stainless steel requires less maintenance and it economical in long use.

Stainless steel is big family, comprises of multiple grades. The most common stainless steel grades are Ferritic, Austenitic, Martensitic, and Duplex stainless steel. Different grade are designed to enhance its qualities. The compositions of carbon and alloying agents vary with each grade.

Austenitic is the most commercial produced grade. It represents the grade 300 series. Grade 316 Stainless Steel is the second most commercial available grade after 304. It is the distinctive, molybdenum holding grade and provides resistance to a certain type of corrosive environment. Its core alloying elements are iron, chromium, nickel, and molybdenum. Molybdenum is the element that distinguishes Grade 316 from other grades. The presence of molybdenum significantly enhances corrosion resistance in the chloride exposed environment.

316H is a higher carbon version of grade 316 stainless steel. It is suitable for applications that required a higher temperature.

Introduction

Grade 316H stainless steel is a higher carbon version of 316 stainless steel. This alloy can be used at elevated temperatures. Increased carbon content provides higher tensile and yields strength. The austenitic microstructure gives toughness even at cryogenic temperature. It offers moderate corrosion resistance in chloride environments. 316H is non-magnetic in nature. It cannot be hardened by heat treatment and can be easily welded and fabricated.

It is ideal for industrial boilers, heat exchangers, and pressure vessel at an elevated temperature at 500°C. 316H is widely used in the petrochemical and oil industry.

Benefits of 316H

  • Higher carbon content enables heat resistance properties.
  • Superior tensile strength

 

Chemical composition

316H is high carbon chromium stainless steel. It contains 0.04- 0.10% carbon with chromium, nickel, and molybdenum as alloying agents.

Grade

Carbon

Cr

Ni

Mo

Mn

Si

P

S

316H

0.04-0.10%

16-18%

10-14%

2.0%

2.0%

0.75%

0.045%

0.030%

 

Physical properties

The physical property of stainless steel is the ability of the material to conduct heat, electricity, expand, and shrink.

Grade 316H attains a metric density of 8.0 g/cm3.

The modulus of elasticity is 200Gpa.

Electrical resistivity is 74 Microhm-cm at 20°C

The melting range is 1375-1400°C

 Thermal properties

Thermal expansion coefficient is 15.9 µm/m° at 1-100°C and 17.5 µm/m° at 538°C

Thermal conductivity is 16.3 W/mK at 100°C and 21.5 W/mK at 500°C.

 Mechanical properties

Grade 316H attains a tensile strength of 515 Mpa and yield strength of 205 Mpa. Hardness is 82B. Elongation is 40% in 50mm. Hardness is 95B

 Magnetic properties

Grade 316H is austenitic stainless steel and non-magnetic in nature.

Heat treatment

Grade 316 H cannot be hardened by heat treatment. It can be hardened by cold working. 316H can be formed easily and cold working operations can enhance its strength and hardness.

Corrosion resistance

Grade 316H offers corrosion resistance comparable to grade 316 most of the time. Grade 316H provides corrosion resistance in sulfur and chloride containing environments. It also performs well in providing good corrosion resistance to pitting in phosphoric and acetic acids.

Grade 316H provides corrosion resistance in freshwater with high levels of chlorides. It is famous for providing excellent corrosion resistance in marine environments.

PRE (Pitting resistance equivalent) is 24

CPT (Corrosion pitting temperature) is 20±2

CCT (Critical crevice corrosion temperature) is <0

Weldability

Grade 316 can be easily welded by standard processes. Post weld treatment is not required with Grade 316 H

 Machinability

Grade 316H can undergo deformation during hardening and is prone to chip breaking. Better machinability can be obtained with slower speed, lubrication, and appropriate tooling.

 

 

APPLICATIONS

Grade 316H is broadly used in the following industries.

•   Petro-chemical industry:

Pressure vessels, tanks, heat exchangers, piping systems, flanges, valves, and pumps.

•         Oil industry

•         Chemical industry

•         Pharmaceutical industries

•         Food and beverage industry

•         Marine

•         Pulp and paper industry

•         Water treatments

•         Textiles

 

Comparison of 316H with 304H/304L

Grade 304 and 316 are two main commercial grades.

 

Composition 

 

  • The critical distinction between the two is the addition of molybdenum alloy in grade 316. The molybdenum significantly enhances corrosion resistance for the chloride environment. 

 

  • Carbon content

           The very basic difference between 316H and 304L/304H is carbon contents.

          These grades are adaptations of standard grade 316 and 304 respectively.

 

Grade

Carbon content

316H

0.04-0.10

304H

0.04-0.10

304L

0.030 max

 

  

 

  

 

 

 

  • 316H and 304H are high carbon stainless steel grades. These grades are designed to progress better strength at elevated temperatures. 

 

  • 304L is low carbon stainless steel and used for applications requiring welding operations of heavy segments. The low carbon prevents the formation of carbide precipitation at the higher temperature.

 

Corrosion resistance 

 

  • Grade 304H/304L endows corrosion resistance in freshwater. It is prone to crevice and pitting corrosion in the incidence of high chloride levels. Grade 316 is recommended for high chloride mediums as it contains molybdenum

           Grade 304H/304L is not suggested with marine environments

 

  • Grade 316H has better chemical resistance than the grade 304H/304L

 

Mechanical properties

 

The common mechanical properties are relatively comparable for 316H and 304H/304L

 

Applications

 

Grade 304H/304L is mainly used in kitchen equipment, storage tanks, indoor enclosures, and pressure vessels.

 

Grade 316H is primarily used for marine equipment, pharmaceutical equipment, chemical equipment, surgical instruments, outdoor enclosure, etc.

 

Costing

 

Grade 316H is more expensive than the 304H/304L stainless steel.

 

To conclude, both the grades constitute comparable qualities. The deciding parameter between the two grades is application design. Grade 316H shows superior corrosion resistance, durability, and its use in marine applications. 

 

Ambica Steels is an eminent producer of stainless steel quality products. Our products are mainly designed for high quality end products. Kindly contact our sales teams for consultations and queries.

Ambica steels offer superior fine quality 316H stainless steel grades. Bars are available in round, square, flat, hexagonal, and customized shapes. Inquiry and orders are welcome.