Chapter 518 (2/2)

Fang Tianxing is not arrogant and complacent. It's the joint efforts of several people who can beat Arnold back this time, not his own credit at all.

If one of his own against Arnold, I'm afraid not the slightest win, his defense is too strong, we must have the means to break armor, otherwise we can't hurt him at all.

Fang Tianxing was walking in the city. At first, many people gathered around him. Fang Tianxing just thought it was a great honor. Later, when he went to some places with few people, there were not many people here who knew Fang Tianxing.

An old man was fishing by the river, and some children were playing football. He walked over and asked, ”do you know what the sharpest thing is?”

The old man who sharpened the scissors replied: ”there is no absolute eternal sharpness. The sharpest thing exists in a certain period of time. The smaller the blade angle, the sharper the blade, the smaller the cutting resistance and the higher the sharpness. It is an important factor affecting the sharpness.

The smaller the radius of the cutting edge, the smaller the cutting pressure and the sharper the cutting edge. This is the key factor to make the cutting tool sharper.

The smaller the angle is, the sharper the blade is, but the cost is the poor edge retention; The larger the angle, the better the edge retention, but the blade will not be sharp enough. ”

Soon the old man said to Tianxing, ”steel can't last long. If the moon is full, it will lose. There is nothing perfect forever. Because the material is steel, it can be thin, very thin, brittle and hard. It will be broken if it's not used well. It's easy to break if it's used violently. It's crunchy and rusty when it's old, but no one ever uses a rusty sword. Which do you think is better? ”

”If there is a balance, both sides can be taken into account.” Fang Tianxing asked.

”The sharpness of the cutting tool mainly depends on three aspects: the shape and angle of the cutting edge, the hardness of the cutting tool, and the internal metallographic structure.

When the geometric angle and surface roughness of the blade remain unchanged, the higher the hardness of the tool, the better the sharpness of the tool, and the more wear-resistant and durable it is. The internal microstructure of steel also has an important influence on the sharpness, but it is not the decisive one. For example, the folding forging process forms numerous small serrations on the blade that are hard to see by naked eyes. It is these small serrations that make the blade extremely sharp. ” The old man said with a smile.

With that, the old man took out a knife beside him, pulled out a hair, loosened his hand on the blade, and let the hair fall naturally.

The hair fell on the blade and was naturally cut in two.

Fang Tianxing's Changkong Zhengqi sword can also do this, but it depends on the sword Qi, not the sharpness of the sword itself. And this one in my hand is an ordinary knife made of iron.

When Fang Tianxing looked closely, the edge of the blade was slightly serrated. When the tooth direction was consistent with the cutting direction, the smaller the cutting pressure, the sharper the blade.

The reason why it is easy to be blunt is that its cutting edge is too thin and easy to wear. And the material is there, it can't be too wear-resistant.

The thin side makes it sharp. It's so sharp that if you blow a pinch of hair at the edge of the knife, the hair will break... Any knife that is so thin will be extremely sharp.

But the feeling of cutting meat with a worn knife is different. It's very blunt, and it takes a lot of effort to pull it slowly. The final reason is that the rusty blade becomes not thin.

”It's true that the tip is the easiest to be damaged, but by increasing the thickness of the blade, it can be greatly avoided.

The point of the knife is the first one to contact the object. The purpose of each part of the knife is clear. For example, the point of the knife is used to poke, pick and stab. It is necessary to find the balance point when grinding. The back blade is mainly responsible for cutting, so it must be sharp.