{"id":15260,"date":"2026-02-06T18:20:00","date_gmt":"2026-02-06T09:20:00","guid":{"rendered":"https:\/\/webstylix.xsrv.jp\/tsr\/?post_type=tips&p=15260"},"modified":"2026-05-24T17:12:37","modified_gmt":"2026-05-24T08:12:37","slug":"blog04","status":"publish","type":"tips","link":"https:\/\/tsrjp.com\/en\/tips\/blog04\/","title":{"rendered":"Titanium helps protect important motorcycles from corrosion."},"content":{"rendered":"\n

The Truth About Titanium, Part 4: \u201cIt doesn\u2019t just resist rust \u2014 it also prevents the other side from rusting.\u201d<\/h1>\n\n\n\n

Most people know that titanium bolts do not rust.
But did you know that they can also make the parts they are attached to less prone to rust?<\/p>\n\n\n\n

What does it mean to \u201cmake the mating part less prone to rust?\u201d<\/h3>\n\n\n\n

If there are bolts that reduce rust, it also means there are bolts that can actually cause rust in the mating material.
This is due to a phenomenon called galvanic corrosion (dissimilar metal corrosion)<\/strong>, which occurs depending on the compatibility between different metals.<\/p>\n\n\n\n

Among them, stainless steel bolts are the worst.
They can trigger this phenomenon against almost any metal, making them something like a \u201cnatural enemy\u201d of metals.<\/p>\n\n\n\n

However, this only occurs under certain conditions.<\/p>\n\n\n\n

What is galvanic corrosion (dissimilar metal corrosion)?<\/h3>\n\n\n\n

It is corrosion that occurs when different types of metals come into contact.
It is also known as electrochemical corrosion<\/strong> or galvanic corrosion<\/strong>.<\/p>\n\n\n\n

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The photo shows a genuine SEROW brake caliper bridge bolt.
Take a look at the threaded section.<\/p>\n\n\n\n

The white material on the surface is aluminum transfer from the caliper.This steel bolt has caused galvanic corrosion, breaking down the aluminum structure.<\/p>\n\n\n\n

As a result, the threads also become worn and reduced in size.
Imagine if this happened on a Brembo caliper or Marchesini wheel\u2014it would be quite alarming.<\/p>\n\n\n\n

By the way, the clean surface on the unthreaded shank area is because it is not in contact with the mating material.<\/p>\n<\/div>\n<\/div><\/div>\n\n\n\n

Mechanism of galvanic corrosion (dissimilar metal corrosion)<\/h3>\n\n\n\n

The cause of galvanic corrosion is the \u201cequalization of electrical potential between metals.\u201d<\/p>\n\n\n\n

Each metal has its own inherent electrical potential.
When different metals are in contact and moisture is present, an electrochemical reaction occurs that attempts to equalize their potentials.<\/p>\n\n\n\n

At this time, electrons move from the metal with lower potential to the one with higher potential.
As a result, the metal that loses electrons dissolves, leading to corrosion.<\/p>\n\n\n\n

The greater the potential difference between the two metals, the more severe the corrosion becomes.
The \u201ctrigger condition\u201d mentioned earlier is actually water.<\/p>\n\n\n\n

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The table shows the electrical potentials of metals in real-world environments.<\/p>\n\n\n\n

If we arrange commonly used motorcycle metals\u2014magnesium, aluminum, titanium, stainless steel, and iron\u2014in order of electrical potential, it becomes:<\/p>\n\n\n\n

Titanium (+0.20) > Stainless steel (+0.15) > Iron (-0.35) > Aluminum (-0.45) > Magnesium (-1.35)<\/p>\n\n\n\n

For example, when stainless steel bolts are used in aluminum products:
Aluminum (-0.45) and stainless steel (+0.15) tend to move toward an equal electrical potential.
In this process, electrons flow from aluminum to stainless steel, and the aluminum, which loses electrons, corrodes.<\/p>\n\n\n\n

So what about titanium? It has an even higher value of +2.0 \ud83d\udca6
This means it is a highly \u201creactive\u201d metal toward other metals.<\/p>\n\n\n\n

HOWEVER!!!!!
As explained in the previous article, titanium is protected by a passive oxide layer.<\/p>\n\n\n\n

This passive layer acts as a barrier, creating an almost insulating state.
Because of this, galvanic corrosion\u2014which is an electrochemical reaction\u2014rarely occurs with titanium.<\/p>\n<\/div>\n<\/div><\/div>\n\n\n\n

The degree of galvanic corrosion can also vary depending on conditions and duration of use.<\/h3>\n\n\n\n

Titanium is not a perfect insulator, so in theory it can still cause corrosion in the mating material.<\/p>\n\n\n\n

However, in real-world environments, moisture and chlorine are limited, and bolts are relatively small components.
For this reason, in practical use, titanium can be considered to cause almost no galvanic corrosion.<\/p>\n\n\n\n

On the other hand, in environments such as underwater or seawater\u2014where electrochemical reactions occur very actively\u2014the electrical potential difference has a direct impact.
In such conditions, it can corrode the mating material even more than stainless steel bolts.<\/p>\n\n\n\n

Avoid stainless steel bolts!<\/h3>\n\n\n\n

Aluminum and iron have a relatively small potential difference, so they can be considered a fairly compatible combination.
In actual use, this is also confirmed to result in relatively low corrosion.<\/p>\n\n\n\n

However! This condition does not last long, because iron is a metal that rusts easily.<\/p>\n\n\n\n

Once the surface coating is damaged, corrosion progresses rapidly.
And that rust can also affect the mating material.<\/p>\n\n\n\n

Therefore, if you want to protect a motorcycle, steel bolts require periodic replacement.
If that is too troublesome, switching to titanium is an option.<\/p>\n\n\n\n

The worst choice is stainless steel bolts.<\/p>\n\n\n\n

Stainless steel also has a passive oxide layer, but its electrical insulation performance is significantly lower compared to titanium.<\/p>\n\n\n\n

When that passive layer is not functioning properly, it becomes more susceptible to electrochemical effects.
In that state, as shown in the table, it can become a highly \u201caggressive\u201d bolt material.<\/p>\n","protected":false},"author":1,"featured_media":15384,"template":"","class_list":["post-15260","tips","type-tips","status-publish","has-post-thumbnail","hentry"],"acf":[],"_links":{"self":[{"href":"https:\/\/tsrjp.com\/en\/wp-json\/wp\/v2\/tips\/15260","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/tsrjp.com\/en\/wp-json\/wp\/v2\/tips"}],"about":[{"href":"https:\/\/tsrjp.com\/en\/wp-json\/wp\/v2\/types\/tips"}],"author":[{"embeddable":true,"href":"https:\/\/tsrjp.com\/en\/wp-json\/wp\/v2\/users\/1"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/tsrjp.com\/en\/wp-json\/wp\/v2\/media\/15384"}],"wp:attachment":[{"href":"https:\/\/tsrjp.com\/en\/wp-json\/wp\/v2\/media?parent=15260"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}