A Complete Surface Finish Chart

The steel surface grade (surface finish) determines its range of applications. In visually focused projects, attractive finishes can enhance the aesthetics and appeal of products. In projects where fabrication is at the center, the correct choice of surface finish can aid in steel detailing and ensure end product quality.

hot-rolled steel topson

Grades of Hot-rolled Steel Surface Finish

Hot rolling refers to steel rolling above its recrystallization temperature to form steel with higher formability and workability. Hot-rolled steel is available in the following 5 finishing grades.

No.1 Finish

No.1 finish has a rough, dull, and non-uniform surface. It is generally used in industrial applications, such as equipment for elevated temperature service. No.1 finish is produced by rolling stainless steel that has been heated prior to rolling. And then, it is annealed to produce a uniform micro-structure and ensure stainless steel meets mechanical property requirements. Pickling is the last but most important step. At this step, the manufacturer will remove the scale on the steel surface to maintain the corrosion resistance of the steel surface.

1U Finish

The surface of 1U steel is formed by hot rolling without further heat treatment and descaling treatment. Due to the surface being covered with scale, it is suitable for metal products that require further thermoforming.

1C Finish

The process flow of 1C finish is similar to 1U finish. The difference is that the 1C finish will be heat treated after hot rolling.

1E Finish

The steel will be processed by hot rolling and heat treatment to obtain better properties. Finally, the scale is removed by mechanical descaling to form a glossy surface. This is 1E steel finish. It can be used for products requiring further processing (hot-rolled or cold-rolled).

1D Finish

The difference between 1E and 1D finishing is the method of removing the scale. Manufacturers remove the scale from steel surfaces by pickling. The 1D finish steel can be used directly or further processed (hot-rolled or cold-rolled).

Grades of Cold-rolled Steel Surface Finish

What is cold-rolled steel? It is actually hot-rolled steel has been further processed. After the hot-rolled steel is cooled to room temperature, roll it with rolls to obtain more precise dimensions and better surface quality. In this process, the steel has a certain temperature but not high. Therefore, more pressure needs to be applied to form the desired shape. Cold-rolled steel is generally more expensive and more technically demanding than hot-rolled steel.

No.2B Finish

No.2B finish is a cold rolled finish with a uniform, smooth, and bright surface. Its processing step is from cold rolled to heat treated and pickled, and finally polished with polished rolls. It is the most common finish with good smoothness and corrosion resistance. You can use it directly or for further processing.

Stainless steel 2B finish is smoother than 2D finish. It can be used in chemical plant equipment, sewage treatment, refrigeration, sheet metal products, etc.

2B finish

Bright Annealed (BA) Finish

Bright Annealed is produced by heat-treating under a controlled atmosphere environment. It can form a mirror-like surface with some imperfections and cloudiness. According to different processes, it can be divided into BA and 2BA.

BA finish has only been bright annealed. While the 2BA finish is polished with highly polished rolls after bright annealing. This process can improve flatness and uniformity without decreasing thickness.

BA and 2BA finish can be used in appliance trim, architectural components, chute liners, radiant heaters, etc.

BA finish

No.3 Finish

No.3 finish is achieved by rough grinding to form a brushed surface with short and parallel polishing lines. You can obtain it by mechanically polishing or special rolling.

If used mechanically polishing, operators must continually adjust the size of abrasives during processing. According to the international standard, 50-80 grits are usually used at the beginning and use 100-120 grits to finish at the end. No.3 finish also can be obtained by using special rolls to press a pattern on the surface.

The surface roughness of the No.3 finish is typically Ra 40 micro-inches or less. It can be used in brewery equipment, food processing equipment, kitchen equipment, etc.

3 finish

No.4 Finish

The stainless steel 4 finish is a more refined surface than the No.3 finish, which has soft glossy and fine lines. It is mechanically polishing based on a #3 finish with gradually finer abrasives. The final finish of #4 can be anywhere between 120 and 320 grit. And its surface roughness is typically Ra 25 micro-inches or less. #4 stainless steel finish is common used in architectural wall panels, kitchen equipment, furniture, etc.

4 finish

No.7 Finish

No.7 finish has a mirror-like surface with high reflectivity. You can see remnants of fine polishing lines on its surface. No.7 finish will be obtained by buffing for up to 10 minutes with grit lines, based on a No.4 finish that has been polished to 320-grit.

No.8 Finish

No.8 finish, known as mirror finish, is the highest reflectivity polished finish covered by the ASTM standards. No.8 finish is obtained by buffing the No.7 finish for five to ten minutes. The resulting finish is mirror-like but not a perfect mirror. No.8 finish has high antibacterial properties, corrosion resistance and aesthetics. Therefore, it is commonly used in ornamental trim, reflectors, clean rooms, etc.

8 finish
David Tan
David Tan
Stainless Steel Materials & Products Expert. With 20+ years of experience in stainless steel, specialize in various stainless steel surface treatments and stainless steel fabricating. Familiar with multiple stainless steel characteristics and applications.

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