On the other hand, it was absolutely impossible to complete this work in such a short period of time. Pen "Fun" Pavilion www.biquge.info

The steel shaft is perfect, straight and has a round section.

"Young master, this steel is really good iron!" Han Laotie couldn't help but praise again. He had already spoken highly of the ingots when he first saw them, but after grinding them by hand, judging by the color of the shaft and the sheen that came out of it, it was better than all the iron he had seen before, including that time.

"Really?" Liu Yuanshan just smiled, touched the bearing glowing with silver-white light, shook his head slightly, and said: "This straight and round can meet the requirements, but there is only one point that is slightly lacking." ”

"What?" Han Laotie asked with his mouth open.

"It's hardness!" Liu Yuanshan said: "The hardness of this steel is too low. ”

Generally speaking, as long as the carbon content is in the range of 2%, the higher the carbon content, the higher the hardness and strength of the steel, and vice versa, the flexibility and toughness are strong, and this change is very significant.

As a wear-resistant part, even high-carbon steel can not meet the hardness requirements.

The source of this hardness is generally the hardness of the material itself, but now Liu Yuanshan's hands and the materials that can be obtained in the current period of time, the hardness of steel has reached the limit.

If you want to increase again, you can only rely on craftsmanship.

Legendary quenching and tempering.

"Hardness? Low? Han Laotie didn't know what the hardness was, but he could understand it after a little thought, but when he heard Liu Yuanshan say that the hardness of this iron was low, he still didn't dare to agree.

"No, no, no, young master, you may not know, this iron is already rare, it is the hardest iron that Xiao Lao'er has ever seen, you don't know these days, for the sake of ......" Thinking about it, it was not a good thing to complain to the boss, Han Laotie decisively stopped. But he still couldn't help but want to use his professional skills to teach Liu Yuanshan a lesson, and said, "Young Master, the hardness of this iron is indeed okay." ”

"You don't know!" Liu Yuanshan couldn't say anything when he suppressed him, but deep down he was still unconvinced.

"What, not convinced?" Liu Yuanshan looked at him with a smile and said, "Come with me, let you see and understand!" ”

In fact, Liu Yuanshan overestimated his attempt to travers, Han Laotie is an old blacksmith, not that he didn't know, but he didn't think of it for a while.

When Liu Yuanshan asked people to reheat the steel shaft, Han Laotie suddenly patted his head and said, "Oh, why did I forget, it's tempering!" ”

Tempering has existed since ancient times, and in modern times, this process is divided into two parts, quenching and tempering.

"You know?" Liu Yuanshan was quite surprised, and at the same time smiled at himself for underestimating the ancients.

"This little old man knows!"

"Then you'd better come!"

Liu Yuanshan is not the kind of arrogant person, he knows the craft and knows many methods, but it does not mean that he will do it better than others.

Since Han Laotie is a blacksmith, since he knows how to temper and quench, then he should still have a lot of experience.

"Be hard!" Liu Yuanshan said again.

The principle of quenching is to heat the steel to a critical temperature into sub-eutectic steel or hypereutectic steel, and then hold it for a period of time to make it fully or partially austenitic, and then cool to below the nearby isothermal temperature with a cooling rate greater than the critical cooling rate for martensite transformation.

Changes in hardness or toughness caused by changes in tissue belong to the physical category, and their essence has not changed, and they are not chemical changes.

I saw Han Laotie clamping both sides of the steel shaft with pliers, burning the steel shaft red in the furnace, and at a certain moment, when he felt that the temperature was just right, he quickly took it out and put it into the prepared salt water.

"Zizi!" A foul white smoke came out, and the salt water in the pool instantly tumbled.

When you feel that the time is right, take out the entire steel shaft.

The temperature on the surface of the steel shaft drops instantaneously due to being soaked in cold salt water, but the temperature in the center of the shaft does not decrease immediately.

The process of reheating by relying on its own temperature countercompensation is called tempering.

The already cold surface gradually warmed up, and then the color also changed, from silvery white to yellowish.

"Yellow, just right!" Han Laotie smiled and put the steel shaft up, and said, "Young master, the hardness, well, hardness of the steel shaft will increase by at least fifty percent." ”

Generally speaking, the tempering temperature and tempering color can roughly correspond as follows: extremely light yellow - 200; Yellowish - 220, brown yellow - 280, blue - 300 degrees.

Therefore, there is a saying that tempering is a return to the blue fire and a yellow fire. It should be hard to return to yellow fire, but brittle; It should be tough and good, but the hardness is low. Han Laotie returned from the yellow fire this time, and the time and temperature were just right, so he had to say that he was an old blacksmith.

"That's good!" Liu Yuanshan was very happy, and asked Shengsheng and Hong Zongwei to help them, and all the remaining steel shafts were quenched and tempered, and I don't know if the hardness can meet the requirements, but at least now this is the hardest thing that can be obtained.

In addition to wear resistance, this tempered hard steel also has a very important use, that is: to make carving knives. A carving knife that can be used to cut patterns or threads on the surface of steel.

The carving knife is very useful for Liu Yuanshan, because it is related to the manufacture of the next screw thread, and it is also the key to whether the double line can be made in the future.

The carving knife uses the hardness and wear resistance of the material, which is no problem, and there should be no big problem after quenching and tempering after this batch of steel is made into a carving knife, but there is a fatal shortcoming: brittle!

That's right, crispy!

Things are always contradictory, and the harder the steel, the more brittle it is. There is no problem with making a carving knife out of steel, but when you turn back to engrave a pattern or steel wire, the knife itself is prone to crumble.

This can only be solved by geometric methods, and the popular practice is to increase the thickness of the component, but the knife relies on the blade, and the thickness is generally very thin. This is not the case in the second case, for example, if the carving knife is made into an obtuse knife, the part of the blade becomes a convergence, but it is slightly sharpened, so that as long as the intensity of the inscription is increased, it will not be damaged.

A job has been completed, Liu Yuanshan secretly breathed a sigh of relief, and next, he can get on the right track.

Now there is still a lot of steel left, and Liu Yuanshan wants to use the remaining steel to make a black technology in the black technology of the traverser, an advanced weapon that can liberate a large amount of productivity in ancient times: the machine.

To put it bluntly, it's a steam engine.

Although the steam engine was a big killer in black technology in ancient times, its principle is not complicated, and in general, it is just a slightly troublesome instrument. (To be continued.) )