304 Stainless Steel Pipes Grade of the most versatile and commonly used stainless steels on the market, Grade 304 stainless steel Pipe is the most standard used alloy of this type. Essentially, Grade SS 304 Pipe is an austenitic chromium alloy which is also known as an "18/8" stainless as the make-up of the steel is 18% chromium and 8% nickel.
The chromium content promotes the material's considerable resistance to the effects of corrosion and oxidation. The stainless steel alloy resists most oxidizing acids and will withstand ordinary rusting though this does not mean that the steel will not tarnish over time. The steel needs to be cold worked to generate higher tensile strength. For stainless steel sections which are welded heavily, post-weld annealing may be necessary to provide maximum corrosive resistance.
Grade | C | Mn | Si | P | S | Cr | Mo | Ni | N | |
304 | min. | ------ | ------ | ------ | ------ | ------ | 18.0 | ------ | 8.0 | ------ |
max. | 0.08 | 2.0 | 0.75 | 0.045 | 0.030 | 20.0 | ------ | 10.5 | 0.10 | |
304L | min. | ------ | ------ | ------ | ------ | ------ | 18.0 | ------ | 8.0 | ------ |
max. | 0.030 | 2.0 | 0.75 | 0.045 | 0.030 | 20.0 | ------ | 12.0 | 0.10 | |
304H | min. | 0.04 | ------ | ------ | -0.045 | ------ | 18.0 | ------ | 8.0 | ------ |
max. | 0.10 | 2.0 | 0.75 | ------ | 0.030 | 20.0 | ------ | 10.5 | ------ |
Grade | Tensile Strength (MPa) min | Yield Strength 0.2% Proof (MPa) min | Elongation (% in 50mm) min | Hardness | |
Rockwell B (HR B) max | Brinell (HB) max | ||||
304 | 515 | 205 | 40 | 92 | 201 |
304L | 485 | 170 | 40 | 92 | 201 |
304H | 515 | 205 | 40 | 92 | 201 |
Surface finish is a critical aspect of stainless steel, as it affects appearance, corrosion resistance, and cleanliness. Below is a terminology table for common terms used to describe the surface finishes for stainless steel:
Term / Finish | Description |
No. 1 | A hot-rolled, annealed, and descaled finish, typically rough and dull. It's commonly used for industrial applications where the finish isn't a primary concern. |
No. 2D | A dull finish produced by cold rolling, annealing, and descaling. May be used for deep-drawn parts or those where a glossy finish isn't necessary. |
No. 2B | A smooth, moderately reflective cold-rolled annealed and pickled or descaled finish. A standard finish for most stainless steel appliances and for sheet metalwork. |
No. 3 | An intermediate polished finish obtained with approximately 100-grit abrasive, typically used where a semipolished finish is required. |
No. 4 | A general-purpose polished finish, typically obtained with a 150-180 grit abrasive. Common in kitchen appliances and elevator panels. |
No. 6 | A soft satin finish having a lower reflectivity than No. 4. It is produced with a pattern of very fine polishing lines. |
No. 7 | A highly reflective finish that is obtained by polishing with successively finer abrasives and buffing extensively until all grit lines are removed. |
No. 8 | Known as a "mirror finish". Highly reflective, with very clear image capabilities, achieved by polishing with successively finer abrasives followed by extensive buffing. |
Hairline | A finish that results in long lines that extend along the length of the coil giving it a patterned texture which resembles hair strands. It's created through a continuous linear polishing. |
Brushed or Satin Finish | Obtained by mechanically polishing the metal with fine abrasives to create a brushed appearance. Less reflective than No. 4 finish. |
Bead Blasted | A matte finish with a frosted appearance produced by propelling a stream of abrasive material against the steel surface. |
BA (Bright Annealed) | A highly reflective finish obtained by annealing in a controlled atmosphere to prevent oxidation, resulting in a bright and smooth surface. |
PVD Coating | Physical Vapor Deposition is a process to produce a metal vapor that can be deposited as a thin, highly adhered pure metal or alloy coating. It is used to enhance surface properties such as color, corrosion resistance, and wear resistance. |
These finishes are used for various applications ranging from aesthetic considerations to functional purposes like enhanced corrosion resistance or reduced particle retention for better cleanability. Selection of the right finish will depend on the requirements of the application and the environment in which the stainless steel product will be used.
Cold rolling and hot rolling are two distinct processes used in the production of stainless steel plates, including those made from 304 stainless steel. Each process has its advantages and results in plates with different properties. Here's an overview of the cold rolling and hot rolling processes for 304 stainless steel plates:
Process:
Advantages:
Properties:
Applications:
Process:
Advantages:
Properties:
Applications:
Grade | Density (kg/m3) | Elastic Modulus (GPa) | Mean Coefficient of Thermal Expansion (μm/m/°C) | Thermal Conductivity (W/m.K) | Specific Heat 0-100°C (J/kg.K) | Electrical Resistivity (nΩ.m) | |||
0-100°C | 0-315°C | 0-538°C | at 100°C | at 500°C | |||||
304/L/H | 8000 | 193 | 17.2 | 17.8 | 18.4 | 16.2 | 21.5 | 500 | 720 |