How austenitic stainless steel joints prevent seizure

Thread galling (or bite) creates a thin layer of oxide on the surface of the metal when the surface is damaged, preventing further corrosion. When the stainless steel fastener is locked, the pressure and heat generated between the tooth lines will destroy and erase the chromium oxide layer between them, so that the metal tooth lines will directly block and shear, and then the phenomenon of adhesion will occur, which will make the stainless steel fasteners completely locked and can no longer be removed or locked.

Causes: Wrong selection of the product Before use, it should be confirmed whether the mechanical properties of the product can meet the requirements of use (such as the tensile strength of the screw and the safety load of the nut).

Rough or foreign matter sticking If solder joints and other metal chips are mixed between the tooth lines, it will often lead to locking.

Use too much force or lock too fast Because electric wrenches often cause the lock speed to be too fast, the temperature rises rapidly and locks.

The nut must be screwed perpendicular to the axis of the screw, and the tilting operation can easily lead to locking.

Unused gaskets The use of gaskets and retaining rings can effectively prevent the problem of over-locking.

Improving lockout can be considered from the following aspects:

1.Choosing the right product:

a.Before use, confirm whether the mechanical properties of the product can meet the requirements of use (such as the tensile strength of the bolt and the safety load of the nut);

b.The length of the bolt should be selected appropriately, and the 1-2 tooth spacing of the exposed nut after tightening shall prevail;

c.Use different grades of screws and nuts, such as 304 with 316 and so on;

d.Use gaskets.

2.Caution before use:

a.Threads must be kept clean;

b.Add lubricants (e.g., 40 oil, butter, graphite, etc.) to lubricate the internal and external tooth lines before use.

3.Correct way to do it:

a.The nut must be screwed perpendicular to the axis of the screw, and must not be tilted;

b.In the tightening process, the force must be uniform, and the force must not exceed the safe torque value;

c.Use torque wrenches or socket wrenches whenever possible, and avoid using movable wrenches or electric wrenches;

d.When used at high temperatures, it must be cooled, and do not rotate quickly during use, so as not to lock up due to rapid rise in temperature (such as electric wrenches, etc.);

e.The use of coating ordinary nuts is an effective lubrication method, and the treated nuts are equivalent to an extra layer of lubrication film.

Apply some lard for cooking when assembling, or go buy an anti-bite agent.

The best way to do this is of course to use a different combination of stainless steels, for example with 1Cr13MOS (corrosion resistance comparable to 304) or 3Cr13 hardening.

Lock-up or seizure often occurs on fasteners made of stainless steel, aluminum alloy and titanium alloys, which are inherently corrosion-resistant and produce a thin oxide layer on the surface of the metal to prevent further corrosion when the surface is damaged. When the stainless steel fastener is locked, the pressure and heat generated between the teeth will destroy this oxide layer, causing the metal threads to be blocked or sheared, and then the phenomenon of adhesion occurs. When this phenomenon persists, the stainless steel fastener will be completely locked and can no longer be removed or locked.

Usually this series of blocking-shearing-adhesive-locking series of actions occurs in just a few seconds, so the correct understanding of the use of fasteners can prevent this phenomenon.

1 Choose the right product. Before use, confirm whether the mechanical properties of the product can meet the requirements of use, such as the tensile strength of the screw and the guaranteed load of the nut. The length of the screw should be selected appropriately, and the distance between 1-2 teeth of the exposed nut after tightening shall prevail.

2 Before use, check the threads for roughness and for iron or dirt between the threads, which can often lead to locking.

3. Fasteners can be lubricated before use. It is recommended to use butter, molybdenum disulfide, mica, graphite or talcum powder for lubrication, and wax dipping treatment is commonly used for lubrication and anti-locking.

4 Pay attention to the method of use when using.

a The speed and force of the screwing should be appropriate, not too fast or too large, use a torque wrench or socket wrench as much as possible, and avoid using a movable wrench or electric wrench. Going too fast can cause the temperature to rise sharply and cause lockout.

b In the direction of force application, the nut must be screwed perpendicular to the axis of the screw.

5 The use of gaskets can effectively prevent the problem of over-locking.

1. The connection between stainless steel and stainless steel is ideally solved by welding (stainless steel sub-arc welding). After welding, it is sanded and polished, and professionals can be "seamless".

2. Other connection methods:

a. Riveting will affect the appearance, and the rivet is easy to stain, which is not conducive to hygiene.

B. Bonding is of course also a better choice, because it can solve the problem by yourself. When handled properly, the appearance will not be affected much. For bonding, it is recommended to use "plastic steel soil".

This kind of glue is relatively hard after curing and drying, very strong and durable, and easy to operate.

The connection of stainless steel to stainless steel can be connected by argon arc welding.

1. Anti-deformation.

2. Rigid fixation.

3. Small parameter welding.

1. The following measures may be taken:

1. Stainless steel electrodes with carbon content less than or titanium or niobium are added;

2. When welding, use small current, fast welding, and the welding rod should not swing;

3. Add copper to fill the plate on the opposite side of the weld to increase the cooling rate of the weld and the heat-affected zone and reduce the heat-affected zone of the weld;

4. Use short arc during welding to reduce the burning loss of CR and Ti;

5. After welding, the solution treatment is carried out, and the weldment is heated to 1050-after quenching, due to the rapid cooling during quenching, the carbide has no time to precipitate, so that the weldment becomes a uniform austenite structure.

2. Tungsten argon arc welding is often referred to as arc welding that generates heat between non-consumable electrodes and working objects; The electrode rod, the bath, the arc and the working object are protected from atmospheric contamination by the gas state, which is a gas or gas mixture**, which must be able to provide full protection, because even a very small amount of air contamination can contaminate the weld bead.

In general, stainless steel does not rust. However, if the stainless steel is not used or maintained properly, or if the environment in which the stainless steel is exposed is too harsh, the stainless steel may rust. When we see yellow or orange rust spots on the surface of steel, we can quickly confirm that this is a sign of rust.

Why does stainless steel rust? First let's understand the structure of stainless steel:

Stainless steel is a crystal solid composed of atoms similar to a patchwork toy. In addition to iron, it also contains its metal components such as chromium, nickel, titanium, etc. Chromium and nickel elements have anti-rust function, which forms a protective film and a blunt film to prevent stainless steel from rusting.

In general, as long as the film is not damaged, cracked, or contaminated with impurities, stainless steel will not rust. However, if the blunt film is damaged due to improper use or maintenance, the stainless steel will rust.

Under what circumstances does stainless steel rust?

There are three basic substances that can damage the blunt surface of stainless steel and corrode it.

Mechanical abrasives.

It refers to things that will scratch the surface of steel, such as: steel wipes, metal wire brushes and metal fragments.

The hardness of the water coming out of our taps varies depending on the area you live in, it may be hard or soft. Hard water has impurities, and when heated, the impurities are static to form a precipitate, which will destroy the blunt surface layer and rust the stainless steel.

Note: Other sediments from processed foods or servings must also be removed in a timely manner.

Bleacher. It's everywhere. Present in water, food, table salt. The worst of these comes from household and industrial cleaners.

The so-called stainless steel is not rusty, but not easy to rust, stainless steel has many kinds of austenite, martensite or something, the common grade has l l ......

According to your use environment, choose the right stainless steel

Stainless steel is actually also called corrosion-resistant steel, which is generally not easy to rust, but it is not excluded that special circumstances, such as long-term put together with acid and alkali things are also easy to corrode, and the protective layer above is destroyed... To prevent rust it is best to apply a little grease (such as lard, wax)...This creates a protective layer.

on the condition to prevent rust.

There are two types of stainless steel: one is acid and alkali resistant, and the other is steam-resistant. How to prevent rust, it is best to prescribe the right medicine.

Stainless steel should not rust, another method is to wipe it clean with a dry cloth after washing, and do not leave water droplets.

Stainless steel is not completely rust-free, so be careful not to do it in places with heavy salt spray. The key is to choose the right grade according to the condition of the place you are using.

Stainless steel will not rust, and those that will rust are stainless iron, and magnets are used to distinguish them, and stainless steel does not suction.

Change to a stainless steel grade that suits your application.

Wipe often with a dry cloth and apply polishing wax over time.

Alcohol sticks to the rag.

Just rub it and it's OK

Ask the landlord, do you mean kitchen utensils or what?

Rubber gloves are required or wiped frequently.