Mechanical Materials for Beginners 1: What are Mechanical Materials? and the Main Classifications of Mechanical Materials (Metals, Iron, Aluminum, etc.)　　　　　　　　　　　

Starting this time, we will begin a new series of our mechanical design course: a course on mechanical materials that even beginners can understand.

So far, we have explained the fundamentals of mechanical design, including how to read drawings, the concept of tolerances, and the mechanics of materials.

The mechanical materials we'll be discussing from now on are just as important, if not more so, than what we've covered so far, so I really hope you'll make sure you understand them.

Because everything that exists in this world is made up of materials, it is quite difficult to manufacture things without understanding those materials.

MoreoverThis is an important matter that concerns not only designers but everyone involved in manufacturing.

Furthermore, in my opinion, as of 2021, when this was written, there was an AI boom in society, and it felt like there was a widespread belief that AI was a panacea, with considerations being made to incorporate programming into education from an early stage.

However, consider this carefully: even if you have excellent software such as computer programs including AI,Without a physical object, the AI ​​or program would be absolutely useless to humans.

For example, AI and programs require physical objects to store them and machines to process them. If humans are using them, they will also need interfaces such as speakers, microphones, keyboards, touch panels, and communication devices, all of which are machines or electromachines.

In other words, between AI or programs and humansIt is absolutely impossible for something to function without the intervention of machinery.

The most fundamental aspect of any machine is its materials, which are extremely important and form the basis of a nation and all industries.

I hope I'm mistaken, but I'm worried that focusing solely on superficial technologies like AI and programming while neglecting the fundamental materials of an industry will lead to serious problems later on.

I believe you now understand the importance of mechanical materials, so let's begin the explanation.

What are mechanical materials?

The difference between chemistry and mechanical materials

First of all, it's easy to imagine that many people would wonder, "What does the term 'machine materials' mean?"

When I entered university, I also wondered, "What's the difference between mechanical materials and materials?" and "Aren't materials something dealt with in chemistry and have nothing to do with machinery?"

Even after attending lectures at university, I didn't quite grasp it, but I quickly understood its importance after joining an automobile company as an engine designer.

I will explain it as clearly as possible based on that experience.

Generally, the topics related to materials that are taught in compulsory education plus high school are mainly classified as chemistry.

The minimum content you learn will likely start with the fact that objects are made up of atoms, and that collections of atoms form molecules that interact with us, and then move on to learning about moles and various chemical reactions.

As far as I can remember, in high school chemistry, we were taught explanations of phenomena (such as chemical reactions), but I don't think anyone was taught how to use materials.

So, regarding chemistry, which many people have encountered...What makes mechanical materials different is that it's the study of "how humans can utilize materials."

For example, we learn about the properties of materials such as strength, ductility, thermal conductivity, and weight, and then consider "how humans can specifically utilize these materials."

What's even more interesting is that it's a field of study that involves learning about the reactions that occur when heat, force, or different materials are applied to them, in order to create materials that are more easily usable by humans.

An example of the general overview of mechanical materials

To put it in simpler terms, I feel it's very similar to cooking.

For example, raw meats such as beef, pork, and fish, as well as various raw vegetables, which are ingredients for cooking, can be eaten raw, but in most cases they are not very tasty and, in some cases, can have harmful effects on humans (such as food poisoning).

Humans process these ingredients by applying heat (baking, stir-frying, boiling, etc.) to make them taste good to them (cook them).

Furthermore, in many cases, multiple ingredients are mixed together or seasonings are added to process (cook) the food into something that tastes better to humans.

This isJust like with mechanical materials, typical materials such as iron and aluminum are completely unusable in their raw form.

Iron, for example, has a wonderful Japanese word to describe its raw, unusable state: unusable iron is called "namakura" (dull), while iron that has been properly processed and is usable is called "hagane" (steel).

The materials are then processed in a way that is easy for humans to use, by changing their properties through heating, cooling, and applying load (heat treatment, residual stress), just like in cooking.

Here's another interesting Japanese phrase: "Strike while the iron is hot," which describes a classic cooking method using iron.

Furthermore, just like cookingBy mixing multiple materials (such as iron and chromium, or aluminum and silicon) or by impregnating them with carbon dioxide or nitrogen gas (like a seasoning), the materials are processed to have properties that are more easily utilized by humans.

What do you think? I think they're quite similar.

Purpose of mechanical materials

In other words, the study of mechanical materials is like learning the properties of raw ingredients, learning cooking methods (such as heat treatment), and understanding what makes a dish delicious (the properties that are useful for humans to use the ingredients).

Specifically, in the materials mechanics discussed on this blog, we have considered the forces generated within the material, but in mechanical materials, we will consider how the material deforms and reacts as a result of those forces.

In other words, It is always paired with mechanics of materials.

Naturally, since we will be dealing with materials similar to those in chemistry, there will be some overlap with high school chemistry. However, I will try to explain things in a way that is as understandable as possible for people who are not good at high school chemistry or who have not had much exposure to it (I myself am terrible at high school chemistry).

Now that you understand the purpose of mechanical materials, let's briefly explain the classification of representative materials in mechanical engineering and the basic properties of each material.

For the section on mechanics of materials, please click here.

Classification of mechanical materials: Metals, nonmetals, iron, nonferrous metals

I will explain the classification of mechanical materials, but the approach differs slightly from that of middle and high school chemistry, so I will focus on "what the differences are" in my explanation.

In middle and high school chemistry, the classification of materials and atoms should be taught based on the periodic table of elements.

The elements in the periodic table are basically arranged in the order in which the number of protons increases, or, to put it simply, in order of mass or in order of similar chemical properties (hydrogen, the first element, is the lightest, and the elements get progressively heavier).

I think many people have the experience of memorizing the Japanese alphabet using the mnemonic "Sui He Ri Be".

The periodic table is also very important in mechanical materials, but we will consider it using a different classification system.

The first thing to be classified isClassify whether it is a metal or a nonmetal.

From an engineering perspective, it is more convenient to consider materials in terms of whether they are metallic or nonmetallic than to use the periodic table.

Looking at it in more detailMetals are classified into two categories: ferrous and non-ferrous metals.

Iron has been an extremely useful material for humans since ancient times, and in the field of mechanical materials, iron is treated as a distinct and established category in itself.

They are also sometimes called iron-based metal materials.

Iron-based metal materials

Those who enjoy history may already know this, but in ancient times, the use of iron was so closely related to humans that it often meant the existence or non-existence of a civilization.

From around 1200 BC, methods for smelting iron were gradually established, and agriculture using iron tools became significantly more efficient compared to the earlier stone and bronze tools. This had a tremendous impact on the advancement of civilization, and the Hittites, who possessed the world's first iron weapons, were able to conquer neighboring countries in an instant and build a vast empire. Iron is a material that has been important to humankind for a long time.

Even in the 19th century, iron was such an important strategic material that even the German "Iron Chancellor" Bismarck famously declared, "Iron is the nation."

Of course, even in the present age of advanced civilization, machine materialsIts basic material is iron, and in terms of overall performance such as strength, cost, ductility, and workability, it is by far the best.

Since we're on the subject, let me introduce some representative iron materials.

SC material is a highly versatile carbon steel containing carbon.

SS steel is a general-purpose steel material whose selling points are its availability and low price.

Chromium-molybdenum (SCM) and chromium steel (SCr) are alloys of molybdenum (Mo) and chromium (Cr), which are somewhat more advanced.

Stainless steel (SUS), an alloy with plenty of chromium (Cr) to make it resistant to rust, is used (the name comes from the English word "stainless," meaning resistant to corrosion).

Gray cast iron (FC) and the slightly higher-grade spheroidal graphite cast iron (FCD) are iron materials used for casting.

There are many other materials as well, including tool steel, spring steel, and sheet metal.

The details will be explained in the section on iron in machine materials, but here's what I want you to remember for now:Most iron-based materials have a specific gravity of 7.8 to 7.85.

Of course, it will vary depending on the type and amount of additives, but since the main component is iron, it won't change that much.

For designers, predicting the weight of the object being designed is a very important skill, so it's a good idea to remember the approximate specific gravities of basic materials.

Next, I will explain the classification of non-ferrous metals.

nonferrous metal materials

このNon-ferrous metals are a rather broad classification; all non-ferrous metals fall into this category.

They're sometimes called non-ferrous metals.

Some of the non-ferrous metals that the author frequently worked with include aluminum, titanium, copper, magnesium, and tungsten.

Although I haven't worked with them professionally, the airsoft guns featured on this blog very often utilize zinc alloy.

These are very often grouped together and referred to as non-ferrous metals.

Humankind's relationship with non-ferrous metals is considerably more recent than that of iron.

While the discovery of non-ferrous metals has a long history, humans only began to seriously utilize them in tools around 1800 AD.

Aluminum, the most familiar non-ferrous metal to us today, cannot be refined without electricity, so its large-scale use only began around 1900 AD, meaning it has a history of only about 120 years.

The widespread use of other non-ferrous metals is a much more recent development than that of aluminum.

Therefore, unlike iron, they are often forcibly grouped together (there is significantly less know-how regarding non-ferrous metals compared to iron).

Here, we introduce the specific gravities of some representative non-ferrous metal materials.

Becomes

Similar to iron-based materials, this also varies depending on the type and amount of additives, but generally, it doesn't vary significantly between materials.

These non-ferrous metal materials will be introduced in more detail later.

Summary of Metal Material Classification

Thus, in the case of mechanical materials, materials are often classified from the perspective of their intended use by humans. This is particularly interesting because, unlike the periodic table which is classified based on chemical properties, the history of humankind plays a significant role in the classification of mechanical materials.

Furthermore, this classification is familiar to technical company employees and is a typical way of dividing materials departments in most manufacturing companies.

For example, manufacturing materials are often divided into ferrous metals and non-ferrous metals divisions (at least all automobile companies are like this).

If any readers are students aspiring to research materials, I hope this will be helpful in deciding on a field of materials science for the future or as a reference for job interviews.

The classification explained so far can be illustrated as follows. A more detailed classification of iron will be introduced later.

Since this is a good stopping point, I will conclude this explanation with the metals iron and non-ferrous metals.

Next time, we'll start with an explanation of nonmetals.

Summary

Now, let's summarize the first lesson on mechanical materials.

Becomes

Next time, I will explain non-metallic materials.

I want to read it together

Mechanical Materials for Beginners 2: Main Classifications of Mechanical Materials (Organic Materials, Inorganic Materials, Composite Materials, FRP, CFRP) In the previous installment on mechanical materials, we introduced the differences between chemistry and mechanical materials, and the first half of the main classifications of mechanical materials. This time, we'll start from the remaining parts of the classification we covered last time. Before that, let's briefly review what we covered last time…

To those who found this article helpful in understanding design:

While there is basically no textbook covering this content, and it is my own original work, I will introduce the textbook that I have been using since I was a student.

Mechanical Materials Science (Basic Mechanical Engineering Series)

created by Rinker

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