{"id":15693,"date":"2026-02-25T14:26:00","date_gmt":"2026-02-25T05:26:00","guid":{"rendered":"https:\/\/webstylix.xsrv.jp\/tsr\/?post_type=tips&p=15693"},"modified":"2026-05-23T22:56:45","modified_gmt":"2026-05-23T13:56:45","slug":"blig07","status":"publish","type":"tips","link":"https:\/\/tsrjp.com\/en\/tips\/blig07\/","title":{"rendered":"Wear is titanium\u2019s only weakness!"},"content":{"rendered":"\n

The Truth About Titanium, Part 7: \u201cTitanium is hard! But in reality\u2026 its wear resistance is poor.\u201d

<\/strong>Titanium is an excellent metal: it is lightweight, strong, and corrosion-resistant.
However, it has one major weakness \u2014
poor resistance to friction (i.e., low wear resistance).

When used in bolts or sliding components, the following types of issues can also occur:<\/p>\n\n\n\n

\n
\n

\u30fbSeizure (it stops turning)

\u30fbGalling (it becomes stuck)

\u30fbIn the worst case, failure or breakage<\/p>\n<\/div>\n<\/div><\/div>\n\n\n\n

Why is titanium poor in wear resistance?
It is due to the following factors:
\u3000
\u30fbBecause it is a metal prone to adhesive wear
\u30fbBecause its passive oxide film is easily damaged<\/p>\n\n\n\n

Now, I will explain the specific reasons and countermeasures.<\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

What exactly is wear?<\/h3>\n\n\n\n

It is commonly thought of as \u201csomething wearing down due to friction.\u201d
But that\u2019s not entirely correct.
More precisely\u2026<\/p>\n\n\n\n

\u201cAn phenomenon in which material is gradually lost due to relative motion between contacting bodies.\u201d<\/span>
In other words, wear is caused not only by friction, but also by factors such as sliding and rolling contact.
Wear can be broadly classified into the following four types:<\/p>\n\n\n\n

\n
\n

Adhesive wear \u2192 surfaces bond and then tear apart

Abrasive wear \u2192 surface is worn away by hard particles

Fatigue wear \u2192 surface damage caused by repeated loading

Corrosive wear \u2192 wear caused by chemical reactions
<\/p>\n<\/div>\n<\/div><\/div>\n\n\n\n

Among these, titanium is particularly weak against adhesive wear!<\/p>\n\n\n\n

What is adhesive wear?<\/h3>\n\n\n\n

Metal surfaces have microscopic irregularities.
When pressure is applied to contacting metals, these tiny asperities bond with each other.
This is adhesion.<\/p>\n\n\n\n


When sliding motion occurs while the surfaces are in this adhered state, the bonded asperities are torn away, causing material loss and surface wear.
This is adhesive wear.<\/p>\n\n\n

\n
\"\"<\/figure>\n<\/div>\n\n\n

In some cases, both surfaces wear, while in others only one side is affected.
In many cases, the softer surface or the one with a weaker microstructure tends to wear.<\/p>\n\n\n\n

However, titanium (Ti-6Al-4V) is a relatively hard metal.
Numerically, it should be resistant to wear.
Nevertheless, adhesive wear still occurs because it has a strong tendency to form adhesion.<\/p>\n\n\n

\n
\"\"<\/figure>\n<\/div>\n\n\n

In the case of titanium, it often damages not only itself but also the mating material. <\/p>\n\n\n\n

Why titanium is prone to adhesion \u2014 \u2460<\/h3>\n\n\n\n

The main reason is that titanium is a reactive metal.
Reactive metals are so sensitive that they can react and even dissolve when exposed to water or acids.<\/p>\n\n\n

\"\"motorockman<\/span><\/div>
\n

In fact, calcium, magnesium, and zinc\u2014commonly found in supplements\u2014are also classified as reactive metals.
It\u2019s easy to understand why they readily dissolve in water or acids.<\/span><\/p>\n<\/span><\/span><\/span><\/div><\/div><\/div><\/div>\n\n\n

Titanium is normally protected by a passive film, which makes it resistant to water and acids.
However, once this passive layer is damaged, it becomes highly vulnerable, and adhesion can occur.<\/p>\n\n\n\n

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\n\t\t\t\t\t\tWhy doesn\u2019t titanium rust!?<\/a>\n\t\t\t\t\t\tThe Truth About Titanium, Part 3: \u201cTitanium doesn\u2019t rust! But in reality\u2026 it is already oxidized.\u201d It is often thought that all material corrosion is caused …<\/span>\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t<\/div>\n\t\t<\/div><\/div>\n<\/div><\/div>\n\n\n\n
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\n\t\t\t\t\t\u3042\u308f\u305b\u3066\u8aad\u307f\u305f\u3044<\/span>\n\t\t\t\t\t
\"\"<\/figure><\/div>\t\t\t\t\t
\n\t\t\t\t\t\tTitanium helps protect important motorcycles from corrosion.<\/a>\n\t\t\t\t\t\tThe Truth About Titanium, Part 4: \u201cIt doesn\u2019t just resist rust \u2014 it also prevents the other side from rusting.\u201d Most people know that titanium bolts do not r…<\/span>\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t<\/div>\n\t\t<\/div><\/div>\n<\/div><\/div>\n\n\n\n

Why titanium is prone to adhesion \u2014 \u2461<\/h3>\n\n\n\n

So why does a passive film that is resistant even to acids break down?
The reason is titanium\u2019s low thermal conductivity.<\/p>\n\n\n\n

Because it is slow to heat up and slow to cool down, the areas in contact during friction can become locally overheated.
This leads to the breakdown of the passive film.<\/p>\n\n\n\n

It should also be noted that, not only in titanium, galling in bolts is generally caused by this type of adhesive wear.<\/p>\n\n\n\n

\n
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\n\t\t\t\t\t\u3042\u308f\u305b\u3066\u8aad\u307f\u305f\u3044<\/span>\n\t\t\t\t\t
\"\"<\/figure><\/div>\t\t\t\t\t
\n\t\t\t\t\t\tBolts That Are Prone to Galling and Bolts That Are Resistant to Galling<\/a>\n\t\t\t\t\t\tThe phenomenon known as \u201cgalling\u201d in bolts is not caused simply by overtightening or a lack of lubrication.Whether galling occurs easily or not depends heavi…<\/span>\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t<\/div>\n\t\t<\/div><\/div>\n<\/div><\/div>\n\n\n\n

Countermeasure 1: Surface hardening (most effective)<\/h3>\n\n\n\n

To prevent adhesive wear, the first priority is to avoid surfaces from bonding in the first place.
An effective way to achieve this is surface hardening.<\/p>\n\n\n\n


As a guideline, a hardness of 1000 HV or higher is used.<\/p>\n\n\n

\n
\"\"<\/figure>\n<\/div>\n\n\n

As expected, DLC (diamond-like carbon) and PVD (ion plating) are effective.
In particular, DLC has many properties that strongly suppress adhesion.
High hardness \u2192 extremely high hardness<\/p>\n\n\n\n

<\/div><\/div>\n\n\n\n

Countermeasure 2: Lubrication (the basic on-site solution)<\/h3>\n\n\n\n
\n
\n

Anti-seize compound
Molybdenum disulfide grease<\/p>\n<\/div>\n<\/div><\/div>\n\n\n\n

Using these can also help prevent adhesion.<\/p>\n\n\n\n

However, caution is required!\u3000There is a drawback in that torque control can become inconsistent.<\/strong><\/p>\n\n\n\n

In fact, a torque wrench does not directly measure clamping force (axial tension).
It estimates the clamping force based on friction (resistance).<\/p>\n\n\n\n

\n
\n

A torque wrench effectively \u201creflects\u201d the following three components:

– Thread friction: ~45%
– Bearing surface (under-head) friction: ~45%
– Actual clamping force (axial tension): ~10%<\/p>\n<\/div>\n<\/div><\/div>\n\n\n\n

Therefore\u2026
Applying grease reduces friction, which can lead to over-tightening.
In addition, variations in the amount applied cause fluctuations in friction.<\/p>\n\n\n\n

As a result, the way grease is applied also requires proper technique.<\/p>\n\n\n\n

Another option is dry lubrication coatings.<\/h3>\n\n\n\n

Some top-level teams even apply dry lubrication coatings to titanium bolts.
The advantages of this include\u2026<\/p>\n\n\n\n

\n
\n

Coating keeps friction constant \u2192 stable torque control
Being a dry film, it does not attract or stick to rubber or contaminants<\/p>\n<\/div>\n<\/div><\/div>\n\n\n\n


At Motolockman, we offer both DLC and dry lubrication coatings.
They are expensive, but high-quality bolts.<\/p>\n\n\n\n

\n
\n
\"\"<\/figure>\n\n\n\n

Dry lubrication coating<\/p>\n<\/div>\n<\/div><\/div>\n\n\n\n

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