Why Do 18-8 Stainless Steel Hex Head Screws Rust?

Why Do 18-8 Stainless Steel Hex Head Screws Rust?

Stainless steel is a high-strength, corrosion-resistant metal material widely used to manufacture various industrial and civil products. Among them, stainless steel 304 screws are commonly used in machinery manufacturing, construction, automobile, ships, and other fields. However, even stainless steel 304 screws will encounter the problem of rust. Next, let's explore why stainless steel 304 screws rust.

1. The composition of stainless steel A2-70 screws

First, we need to understand the composition of stainless steel 304 screws. Stainless steel 304 comprises nickel, chromium, manganese, and silicon, and the steel contains 18% chromium and 8% nickel. This composition gives stainless steel high strength and good corrosion resistance. In addition, stainless steel 304 has small amounts of carbon and iron added. But even such a stainless steel with corrosion resistance, there will be the problem of rust.

2. Incomplete oxide formation

Although there is no rust on the surface of stainless steel A2-70 visible to the naked eye, its surface is often covered with a thin oxide layer. The reaction of chromium and oxygen forms this oxide layer, which has good corrosion resistance. However, the oxide skin on the surface of stainless steel 304 is not complete. There are many defects, especially in the process of forming the surface of stainless steel, if it contains impurities, hydrogen, bubbles and other undesirable factors, it will lead to the oxide skin is not complete, and these defects become the hidden danger of the occurrence of rust.

3. Stainless steel A2-70 screw surface contamination

Stainless steel A2-70 screw surface pollution is one of the main reasons for the occurrence of corrosion. Due to the use of different occasions, the screw surface is often in contact with a variety of debris, such as dust, oil, sand, etc. This debris will be attached to the screw surface to form a contaminated layer, affecting the integrity of the oxide skin. In addition, if you do not clean the screw surface in time, glass fiber and steel dust, and other rough materials may also be contaminated layers stuck in the thread groove and the deep formation of deposits, thereby accelerating the formation of rust.

4. Use of harsh environmental

The use of stainless steel A2-70 screws in environmental conditions will also affect whether it will rust. For example, when using stainless steel screws in a humid, dusty, high salinity, or high pH environment, it is easy to cause the oxide skin on the surface of the screw to rupture and fall off, resulting in rust. In addition, vibration and deformation can also damage the integrity of the oxide skin, leading to rust on the surface of the screw.

18-8 Stainless Steel Hex Head Screws: Made from 18-8 stainless steel, these screws have good chemical resistance and may be mildly magnetic. Length is measured from under the head.

Metric screws are also known as A2 stainless steel screws.

Black-oxide screws have a black appearance.

Match the thread spacing of mating components. Coarse threads are the industry standard; choose these screws if you don’t know the pitch or threads per inch. Fine and extra-fine threads are closely spaced to prevent loosening from vibration; the finer the thread, the better the resistance.

Screws that meet ASME, ISO (formerly DIN), or DIN specifications comply with these dimensional standards.

Mil. Spec. 18-8 Stainless Steel Hex Head Screws: Choose these screws for their adherence to strict military standards for material and construction. Made from 18-8 stainless steel, they have good chemical resistance and may be mildly magnetic. Dimensions meet Fed. Spec. FF-S-85 specifications. Length is measured from under the head.

Match the thread spacing of mating components. Coarse threads are the industry standard; choose these screws if you don’t know the threads per inch. Fine threads are closely spaced to prevent loosening from vibration.

Left-Hand Threaded 18-8 Stainless Steel Hex Head Screws: Tighten these screws by turning them to the left; once fastened, they prevent counterclockwise-moving parts from loosening. Made from 18-8 stainless steel, they have good chemical resistance and may be mildly magnetic. Length is measured from under the head.

Super-Corrosion-Resistant 316 Stainless Steel Hex Head Screws: More corrosion resistant than 18-8 stainless steel screws, these 316 stainless screws have excellent resistance to chemicals and salt water. They may be mildly magnetic. Length is measured from under the head.

Match the thread spacing of mating components. Coarse threads are the industry standard; choose these screws if you don’t know the pitch or threads per inch. Fine threads are closely spaced to prevent loosening from vibration.

Screws that meet ASME, ISO (formerly DIN), or DIN specifications comply with these dimensional standards.

Stainless Steel Hex Screw and Nut Kits for Pipe Flanges: Use these kits to connect standard-size stainless steel pipe flanges for ANSI Class 150 or 300. They meet ASTM specifications for material quality, and the dimensions meet ASME specifications. The length of the screws is measured from under the head.

18-8 stainless steel kits have good chemical resistance and may be mildly magnetic.

Three hundred sixteen stainless steel kits are more corrosion resistant than 18-8 stainless steel and have excellent resistance to chemicals and salt water. They may be mildly magnetic. Some kits have blue PTFE-coated nuts. This coating is slippery, chemical-resistant, and prevents galling. It also helps nuts thread smoothly.

Stainless Steel Flanged Hex Head Screws: Made from 18-8 stainless steel, these screws have good chemical resistance and may be mildly magnetic. The flange distributes pressure where the screw meets the surface, eliminating the need for a separate washer. Head height includes the flange. Length is measured from under the flange.

Inch screws meet ASTM F593 material quality standards and IFI 111 dimensional standards.

Metric screws meet DIN 6921 dimensional standards.

Stainless Steel Flanged Hex Head Screws with Slotted Drive: Install these screws with a wrench or a screwdriver. The flange distributes pressure where the screw meets the surface, eliminating the need for a separate washer. Dimensions meet ASME B18.6.3 specifications. Head height includes the flange. Length is measured from under the flange.

18-8 stainless steel screws have good chemical resistance and may be mildly magnetic. Three hundred sixteen stainless steel screws are more corrosion resistant than 18-8 stainless steel screws and have excellent resistance to chemicals and salt water. They may be mildly magnetic.

Match the thread spacing of mating components. Coarse threads are the industry standard; choose these screws if you don’t know the threads per inch. Fine threads are closely spaced to prevent loosening from vibration.

Measures to protect stainless steel 304 screws from rust

For the above points, we need to take some measures to protect the stainless steel A2-70 screws from rust. First of all, it is necessary to ensure that the surface of the manufactured stainless steel A2-70 screws is intact during the production process. Secondly, it is recommended that the surface of the screws be checked and cleaned regularly during the use process, especially the screws used in polluted environments should be paid extra attention to. For the use of stainless steel 304 screws in harsh environments, it is necessary to use rustproof screws with better corrosion resistance and strengthen the maintenance to extend the service life.

In short, the stainless steel A2-70 screws rust problem is not as severe as ordinary steel screws, but we also need to pay extra attention to production and use. Long-term use also requires frequent inspection and maintenance to ensure the good use of stainless steel screws.For high-quality High-Strength Extreme-Strength Stainless Steel Flanged Hex Head Screws for Sheet Metal and professional technical support, please get in touch with us at adelajonly@gmail.com or visit our website at https://www.juxinfasteners.com.