Chapter 3

In the blacksmith's shop, a coal-fired furnace was blazing, and it was evident that Old Zhang had been forging iron just moments ago. He had only put down his work when he heard their voices and came out.

Qin Hai, in his previous life, was a man with a wide range of interests. To explore traditional folk material processing techniques, he had once worked as an apprentice in a blacksmith's shop for a few days. Therefore, he had some knowledge of the tools and rules in a blacksmith's shop. He picked up a pair of tongs from the ground, clamped the damaged shovel head, and placed it in the fire to begin the heating process.

"Bro, do you really know how to quench metal?" The fat man had somehow sneaked in and asked Qin Hai in a low voice.

It was mid-summer, and the temperature inside the blacksmith's shop was about 7-8 degrees higher than outside, almost like a steamer. Qin Hai, who was already finding it hard to bear the heat, noticed that the fat man, who was particularly sensitive to heat, had also come in, completely ignoring the sweat streaming down his body. This showed how much he cared about the matter.

"Can you forge iron, brother?" Qin Hai did not answer the fat man's question but asked a counter-question.

"I'm a forger," the fat man replied. "All these farming tools were made by me."

"That's great," Qin Hai said. "The shovel blade is curled, and it needs to be re-forged. I'll leave this to you."

"…Okay," the fat man nodded hesitantly. Since Qin Hai was already helping with the quenching, he couldn't ask him to swing the hammer as well.

Qin Hai heated the shovel head to a certain temperature, then used the tongs to take it out and place it on the anvil. The fat man, who was a skilled forger, picked up a large hammer and began to forge the shovel head. Since it was just a repair of the curled edge, the forging work was not extensive. After a few strikes, Qin Hai told him to stop.

"Is it ready for quenching now?" The fat man pointed to a basin of water and asked Qin Hai.

"Not yet," Qin Hai waved his hand and put the forged shovel head back into the furnace to reheat it. He watched the color of the shovel head through the flames, waiting for it to reach the desired temperature.

"What are you waiting for?" The fat man, seeing Qin Hai's serious expression, also became solemn and asked in a low voice.

"Heat treatment is not that simple. First, you need to heat the metal to the Ac3 point, which is the temperature at which free ferrite completely transforms into austenite, causing solid solution strengthening. Then, you take it out and cool it slowly in the air to refine the grain structure and distribute the carbides evenly…" Qin Hai explained the basics of heat treatment to the fat man in a low voice.

"This… is too complicated," the fat man directly rejected the postdoctoral fellow's explanation. Terms like austenite and grain structure were too distant from him. He only cared about when he could see the results of the quenching.

Outside the blacksmith's shop, Old Zhang was chatting with Manggu while secretly observing the activities inside. Seeing Qin Hai heating the workpiece slowly, his playful expression turned slightly serious.

"What's wrong, Old Zhang?" Manggu noticed the change in Old Zhang's attitude and asked in a low voice.

Old Zhang said, "This young man seems to know what he's doing…"

"Better than you?" Manggu laughed, knowing that Old Zhang always prided himself on his skills and liked to boast. Now, hearing that a young man had some skills, he couldn't resist the opportunity to tease him.

Old Zhang said insincerely, "Compared to me, he still has 20 years to go… But I don't understand what he's doing…"

At that moment, the short young man who had gone to fetch the chemicals came back, panting heavily, with a cloth bag in his hand containing several bottles of chemicals.

"Hey, where's the passerby?" The short young man asked the tall man waiting outside. Qin Hai had not introduced himself, so he referred to him as "the passerby."

The tall man nodded his head toward the inside and said, "He's inside, and he's already forged the iron."

"Did I come too late?" The short young man was a bit disappointed.

"Not late, just in time," Qin Hai said from inside. "Did you get the stuff?"

"I got it all," the short young man replied happily. He had run a long distance in the heat, and it would have been frustrating if the items were not used.

Qin Hai had already taken the heated shovel head out but did not immediately plunge it into the water. Instead, he threw it into a pile of furnace ash to maintain its temperature. This process is called tempering, one of the major heat treatment processes. When Qin Hai said he would quench the farming tools, it was a general term. What he intended to do was a comprehensive heat treatment, combining normalization, tempering, and quenching.

While the shovel head was being kept warm, Qin Hai took the chemicals the short young man had brought and began to pour them into the quenching basin. Precise weight control was impossible, so Qin Hai could only estimate the appropriate amount of chemicals and mix them into the water.

"Hey, young man, what are you doing?" Old Zhang had entered the blacksmith's shop and, seeing Qin Hai's busy work, became curious.

Qin Hai turned and smiled at Old Zhang, saying, "I'm preparing the quenching solution. This 65# manganese steel needs to be quenched in a trinitrate solution for the best results."

"I've never heard of that," Old Zhang said in surprise. "Isn't quenching just done with water?"

"Have you heard of oil quenching?" Qin Hai asked.

"Oil quenching… I've heard of it," Old Zhang said. Oil quenching involves using plant oil instead of water as the quenching medium, and its effect is different from water quenching. Old Zhang knew that some iron tools were better quenched in oil, but it was rarely used due to the high cost.

Qin Hai said, "The principle is similar to oil quenching. Different materials and different uses require different quenching processes, involving different media. The trinitrate solution I'm using is the most suitable for this type of steel."

"Trinitrate…" Old Zhang was completely baffled. If Qin Hai was wrong, he wouldn't have spoken so confidently; but if he was right, Old Zhang had never heard of trinitrate. Could this young man know more than he, an old blacksmith?

"You'll see the results soon," Qin Hai smiled, not wanting to explain further. The scientific principles of material heat treatment were beyond the understanding of a folk blacksmith, but this did not prevent these blacksmiths from finding heat treatment methods that even material experts would admire through instinct and years of practice.

Qin Hai took the cooled shovel head from the furnace ash and reheated it until it turned slightly red. He then took it out and plunged it directly into the prepared trinitrate solution.

"Zhis!"

A clear sound of water, and a cloud of steam rose from the quenching basin. Everyone in the room smelled a strange, neither sour nor salty odor. Qin Hai let the shovel head soak in the water for a minute or two, then took it out and threw it on the ground, saying to the fat man, "It's done. Take it out and let the uncles test the blade."

"Really done?" The fat man was overjoyed and, ignoring the residual heat on the shovel head, picked it up and went outside.

"It's done. Try it out," the fat man called to the farmers.

"Done?" the farmer named Manggu asked. He took the shovel head, examined it carefully, and nodded. "Hmm, the color looks right. But I wonder if it's strong enough…"

"Can this shovel really cut through bricks?" another farmer asked, referring to the earlier bet.

"Um…" The fat man was a bit unsure. He didn't know if Qin Hai was exaggerating. If the tool failed after all the effort, it would be embarrassing.

"No problem, go ahead," Qin Hai came out of the shop, smiling and said.

Hearing Qin Hai's confidence, Manggu became curious and wanted to see if the shovel was as strong and durable as Qin Hai claimed. He attached the shovel head to a wooden handle, found a half-brick, and lightly tapped it with the shovel, asking Qin Hai, "Young man, can this shovel really cut through bricks?"

"Go ahead," Qin Hai said confidently. 65# manganese steel is a widely used material, and in the future, extensive research had been done on its heat treatment. If this heat treatment failed, Qin Hai would have to reconsider his life.

Manggu was still hesitant. He struck the brick a few times with the shovel, checked the blade, and seeing no damage, he swung the shovel with all his might at the brick.

"Bang!"

The brick shattered into several pieces. Hearing the crisp sound of the shovel hitting the brick, everyone except Qin Hai couldn't help but grimace, thinking the blade must have a small chip. Manggu quickly lifted the shovel, wiped off the remaining brick dust, and looked closely, laughing out loud, "Ha, it's completely fine!"

"Let me see!"

"Let me see!"

The other farmers and Old Zhang crowded around to inspect the shovel's blade. They saw only a faint scratch where the brick had been hit, with no signs of damage or curling. Everyone could feel the force Manggu had used, and the fact that the blade remained unscathed under such impact demonstrated its excellent quality.

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In the first week of the new book, updates are a bit slow, with one chapter of 3000 words per day. I'm working hard to stockpile chapters. Starting from the second week, I'll try to update two chapters per day. During the new book period, I seek recommendations, clicks, and collections.

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