Liu Yu replied without thinking: "Naturally, you have a good grasp of the heat!" ”

Murong Nan nodded: "What is the heat, and how to master it?" ”

Liu Yu said with a smile: "The heat is to look at the color of the fire, and when it comes to cyan, it is also the time when the steel juice can be melted. ”

Murong Nan continued: "Then do you know what needs to be done to make the furnace fire turn this cyan? What kind of material should be used to make a fire, and how to set up a furnace and blow air? ”

Liu Yu was slightly stunned, he hadn't cared much about these things, in the blacksmith camp these days, he had only learned to look at the cyan fire, and asked Murong Nan such a question, so he began to think carefully about the experience of steelmaking these days.

"Our stoves," he said, "are made of clay and coated with a special layer of clay, which is said to prevent the fire from blowing up the furnace, and the hot air from the furnace is returned to the furnace through a stone pipe to make the fire stronger. As for this blower, it is to pull the bellows by hand, the person who blows the wind needs excellent strength, and strong endurance, often have to pull for an hour or two at once, I have drummed a few times, but it is much more tiring than striking iron, so it is generally half an hour to rotate. ”

Murong Nan nodded: "Being able to repeatedly pour hot air back into the furnace and use this kind of closed blast furnace is already quite good, it seems that the iron-smelting technology in the Central Plains is very high." But have you ever noticed what the fuel is that you throw into the furnace? ”

Liu Yu's eyes lit up and said, "Isn't it charcoal?" ”

Murong Nan smiled and shook his head: "It seems that you haven't observed it carefully, if it's just those charcoal from logging and burning, you won't be able to make the furnace fire turn blue, and you won't be able to refine the steel juice." What you put in there and burn it is not charcoal, but graphite, or coal! ”

Liu Yu said: "Graphite? ”

Murong Nan Zhengse said: "Yes, this graphite is a kind of black thing buried in the ground, use it as fuel, the furnace fire that is burned can become cyan, if it is only charcoal, then the most that can be burned is pig iron, and the fire color in the furnace will only turn red, and it is impossible to turn blue, and there is no way to talk about steelmaking." ”

"Liu Yu, I don't know if you have paid close attention to it, the pig iron and wrought iron are turned into steel after adding charcoal powder, and then these steel blocks have to be re-refined many times to remove their impurities, and many of them will condense into black, small ball-like things after oozing out, this is graphite, or coal."

Liu Yu suddenly thought of the situation of steelmaking, and it was exactly the same as what he said, and nodded: "You are right, there are indeed such small pieces of black particles, this is graphite?" ”

Murong Nan smiled slightly: "Yes, this is graphite, use this graphite as fuel to make steel." By now you should know why the fire turns green. ”

Liu Yu sighed: "I still observed too coarsely, and I didn't even pay attention to these." Thanks for the reminder. Is there any way you can make this furnace change its color beyond the cyan color, and make more powerful steel? ”

Murong Nan shook his head: "We don't have this ability, in fact, these things were not discovered by blacksmiths at the earliest, but by those alchemy pills, they need the furnace fire to be hotter in order to make alchemy, so they try all things in the world, and finally can continue to provide this fierce fire steadily, so that the furnace fire turns blue, only graphite." ”

A hint of disappointment flashed in Liu Yu's eyes: "Then since there is no better fuel than the current graphite, how can we make good steel?" ”

Murong Nan smiled slightly: "Actually, what I want to tell you is not how hot this furnace can be, but how to make the extremely hot steel juice cool down quickly." ”

Liu Yu's expression changed: "Cool? His brain was full of lightning, and he suddenly thought of the first time he saw Kong Jing, that is, in order to be lazy, there was a guy who did not go to the mountain spring water in the early morning, but tried to use river water to fill the number, and as a result, Kong Jing broke a finger.

He nodded thoughtfully: "I understand what you mean, Lord Kong takes this cool thing very seriously, and will even punish those servants who fetch water heavily for this. Looks like you're going to play tricks with this cooling method? ”

Murong Nan nodded: "This is the mystery I want to tell you, you Han people will only try their best to make a fuss about the water quality, either using snow-covered water, or mountain spring water in the morning, or clear stream water, etc., etc., etc., but you have never thought that everything in this world can only be cooled by water." ”

Liu Yu's eyes lit up: "Then what else can be cooled?" ”

Murong Nan laughed: "This is the reason why we Hu people can create elite armor, because we deal with livestock all day long, so we can invent a good way to make these red-hot steel cool down quickly or slowly." That's the urine and grease of cows and horses! ”

Liu Yu's eyes widened: "What, you can control the cooling speed with urine and grease?" ”

Murong Nan nodded: "You can try it yourself, from extreme heat to room temperature, this is quenching, generally speaking, the colder and icier the water, the faster the cooling speed, but the cooling time is not easy to master, after all, water is water after all, even if there is a difference in material, but it will not be too different, it is nothing more than the difference between stainless steel and good steel." ”

"But if you control the quenching time, put it in the horse urine, it can be condensed into steel after a moment, and put it in the grease, you can slowly cool it after a night, and then what you get is not ordinary steel, but something between steel and wrought iron, in our grassland, we will call extremely hard steel iron, and this thing between steel and wrought iron, called finger wrapping, now you know how they came from."

Liu Yu laughed, grabbed Murong Nan's hand, and shook it vigorously: "Brother Murong, you really helped me a lot!" ”

At the moment when he grabbed Murong Nan's hand, Murong Nan instinctively wanted to withdraw this hand as if he had been electrocuted, but it was held tightly by Liu Yu's big hand like iron tongs, how could he still pull it away for half a minute, Liu Yu could even feel that his palm quickly began to sweat, and his expression became extremely unnatural.

Liu Yu was a little too excited under ecstasy, and when he saw Murong Nan like this, he also reacted, let go of the hand holding him, and said with a smile: "I'm sorry, I'm so happy, it's a little rude." ”

Murong Nan hooked the corners of his mouth, stood up, and said coldly: "I hope what I said will help you, I'm leaving, I wish you success." ”