Gears are some of the most important components in the world. It’s their job to transmit motion, controlling speed, direction, torque, and power. They offer some incredible advantages, including zero slippage and drift, plus consistency and efficiency. As a result, they are essential for industrial machinery, medical equipment, automotive and aerospace. However, you need to think about corrosion and the catastrophic impact it can have. We want to look at that here, then you can rely on us if you need highly resistant materials like 1.4435 and 1.4439 stainless steel for parts.
The impact of corrosion
As you probably already know, corrosion is one of the worst things that can happen to many materials. It causes the deterioration of the mechanical and chemical properties. Most importantly, it compromises the strength, integrity, and service life. In the worst cases, machinery, vehicles, and structures can fail.
Corrosion can increase the risk of injury, loss of life, environmental damage, and economic harm, especially when you’re dealing with gears. There are risks in every application, including low-cycle operations and high-speed machining.
Because of the risk, you need to think very carefully about what materials you will use for gears. Significantly, consider the environment and operating conditions. You need to select materials that will be able to withstand it. If you need higher corrosion resistance, 1.4435 and 1.4439 stainless steel are excellent.
Three types of corrosion
One of the key things to look at is the different types of corrosion and the impact they can have on gears. Crucially, when you’re manufacturing them, they could corrode in a matter of hours. You need to be careful, ensuring you choose the right processes (broaching, hobbing, or machining) and take steps to protect materials, including using lubrication and rust inhibitor or preventative.
Pitting
This is one of the worst types because it can be very hard to detect. There may be no localised corrosion to even indicate there is a problem. Or, the rust could hide the flaws. Plus, it can be difficult to see the extent of the pitting without looking at the cross section. It may only seem like small holes at first, but further inspection could show wide, deep holes below the surface.
In some cases you can disregard pitting, especially if there are only a small number of them in different locations on the gear. However, if there is a large number in close proximity, it could compromise the mechanical properties enough to allow bending fatigue failure in gears. Speak to us to learn about 1.4435 and 1.4439 stainless steel.
Crevice
Corrosion can occur in locations where the local chemical environment is more corrosive than the surroundings. This includes key areas such as below washers, under seals, and in threads. So, there can be a big risk for gears because of the teeth and other features.
The main problem with crevice corrosion is it can be very difficult to detect. In fact, it can go unnoticed unless you check gears very carefully. It happens in areas where liquid is trapped and oxygen is depleted, so it can cause rapid material loss in a short space of time and penetrate deep into the material. It can lead to catastrophic failure.
Intergranular
Finally, we have a type of corrosion that affects the boundaries between the grains in a material. It is incredibly dangerous due to the fact it breaks down the bonds and creates cracks and crevices within the material. They can be completely undetected.
The big issue here is the intergranular corrosion generally proceeds through the material, following the grain boundaries. As a result, it has a huge impact on the mechanical properties. It opens the door for stress corrosion cracking and gear failure.
Try 1.4435 and 1.4439 stainless steel
If you want to create exceptional gears that will provide a fantastic service life, make sure you choose the right materials. Most importantly, think about the mechanical properties and corrosion resistance.
One of the best options is 1.4435 stainless steel. It’s an austenitic grade with higher molybdenum content (2.5-3%). This, along with the inclusion of nickel and significant amount of chromium (17-19%), means the material has very high corrosion resistance. This includes higher pitting resistance and the ability to withstand chloride, sulfuric, and organic acids. It can comply with standards for numerous applications in the chemical industry, including gears.
An alternative option is 1.4439 stainless steel. Notably, it has even higher molybdenum (4-5%), plus high chromium and nickel. As a result, it has impressively high resistance to pitting and crevice corrosion. If you compare to 1.4435, it has a higher yield point. Again it is suitable for use in the chemicals industry.
Both of these materials are useful for manufacturing gears, particularly for use in harsh corrosive environments. They can provide massive benefits, including a longer service life in chemical and marine applications. The wear resistance is good too. However, you must note they are not ideal for high load/high speed equipment. Typically they are best for moderate loads.
Order exceptional materials
If you need materials for an ever-growing list of applications, Brindley Metals can help. We have one of the most extensive ranges in the UK, including specialist alloys and forms that few businesses deal with. It includes 1.4435 and 1.4439 stainless steel and much more. Notably, we support clients in different industries, including gear manufacturers.
So, get in touch today and tell us your specifications; we can suggest materials and give you the best support.