Chapter 2

So-called quenching is a process in metal material processing. Simply put, it involves heating a metal workpiece to a certain appropriate temperature and maintaining that temperature for a period of time, then quickly cooling it by immersing it in a quenching medium. In traditional blacksmith shops, after forging various iron tools, the red-hot iron tools are quickly immersed in water for cooling, which is one way of quenching.

Quenching, along with tempering, annealing, and normalizing, is collectively known as heat treatment processes, which are important methods for improving material properties. By precisely controlling factors such as the medium, temperature, and time in heat treatment processes, the toughness, strength, hardness, wear resistance, and fatigue strength of materials can be brought to specified requirements. The knowledge involved in this is profound and complex.

As a material expert, Qin Hai has a deep understanding of heat treatment processes. He just glanced at the farm tools made by the fat man and his group and knew that they had not undergone quenching. 65# manganese steel is an excellent steel with both high toughness and wear resistance, but if it is not properly quenched after processing, the steel will be too soft, leading to the current issue of the blade rolling.

The fat man and his group were all half-trained apprentices, who only had a superficial understanding of processing techniques. They even couldn't immediately react to the term "quenching" that Qin Hai mentioned. According to the dictionary, the character "quench" should be pronounced as "cui" (脆), but in the field of heat treatment, people are accustomed to pronouncing it as "zhan" (战), which is derived from the traditional northern term "dip fire" (蘸火).

"Are you talking about 'cui' fire?" The short one of the three young men asked tentatively.

"Um, it can also be pronounced that way," Qin Hai compromised. This wasn't the time to popularize terminology; as long as the other party understood his meaning, it was fine.

"We couldn't... find water at the time," the short one replied in a barely audible voice. As an apprentice, even if he hadn't eaten pork, he had seen pigs run. He had at least seen the quenching process, but didn't know its purpose. When making these farm tools, perhaps as he said, they skipped this step because there was no convenient cooling water nearby.

"What? You sold your iron tools without quenching them, and you still dare to call them quality products!" The farmers, who had a good reason, all shouted together. Although they didn't understand industry, they had at least seen blacksmiths at work and knew about quenching and that unquenched iron tools were not durable.

"Refund!"

"Refund the money!"

"Make them pay!"

The farmers shouted with righteous indignation, waiting for Qin Hai to speak up for them.

"What do you think, gentlemen?" Qin Hai asked the three young men.

The fat man's tone was a bit soft, mumbling, "They just want to extort us. We used good steel... even if it wasn't quenched, it's still good steel... this good steel is even cheaper than the blacksmith shop by fifty cents..."

He was talking to himself, but his meaning was very clear: he was unwilling to refund the money. The five farmers had bought about seven or eight farm tools from them, worth over ten yuan. If they all returned, they probably couldn't afford it.

Qin Hai saw the fat man's dilemma and turned back to the farmers, saying, "Uncles, let me suggest a solution, okay?"

"Go ahead," the farmers said.

Qin Hai said, "Since you've bought these farm tools from these young men, I assume they are useful at home. The steel used in these tools is indeed of high quality; it just lacks one processing step. If you are willing, I can have these young men reheat the tools and complete the quenching process. I guarantee that after the repair, the quality of these tools will be better than what you've used before. What do you think?"

"Hey, do you know what quenching is? We don't understand it," the fat man pulled on Qin Hai's shirt, afraid that Qin Hai's words would get them into trouble.

Qin Hai gave the fat man a look of disappointment and said, "Since I've promised, I have confidence... but you need to help me find a blacksmith shop and some quenching medium. I'll explain it to you later."

By this time, the farmers had exchanged opinions and decided that continuing to argue with the fat man and his group wouldn't lead to a solution, and they indeed needed these farm tools. They nodded and said to Qin Hai, "For your sake, as long as they can repair these tools and ensure they don't roll, we won't return them."

"Who can guarantee they won't roll!" The tall young man interjected inappropriately, "If you use a spade to cut bricks, it won't roll either?"

"Good quenching can indeed prevent rolling," Qin Hai replied with a smile.

"Alright, just for your words, if you say that after quenching, this spade can cut bricks without rolling, I'll buy all the farm tools on this stand!" The leading farmer used a provocation, thinking that Qin Hai's words were exaggerated, but by supporting Qin Hai, he could force the three young men into a corner, which he found very satisfying.

"Did you say that? Alright, buddy, tell me, how do we do the quenching?" The fat man's blood was stirred by the farmer's words. He suddenly had a desire for Qin Hai to really make these tools capable of cutting bricks without rolling, so he could force the farmer to buy the remaining tools. This wasn't just about making money but also about regaining lost face.

Qin Hai looked at both sides, shook his head helplessly, and said to the three young men, "To do quenching, we need a furnace... you are from a factory, right? Should we go back to your factory or find a blacksmith shop? What do you think?"

"Let's find a blacksmith shop," the short one said. Selling farm tools for money was their side job, and it was better not to involve the factory.

"There's Zhang Lao San's blacksmith shop not far from here. I know him well; I can take you there," the leading farmer pointed in a direction and said.

"Alright." Qin Hai nodded and said to the young men, "There's one more thing you need to find. I need to prepare some quenching solution, which requires several chemicals. These chemicals can only be found in a high school laboratory. Do any of you have connections?"

"I do..." the short one raised his hand and said, "My uncle is a teacher at the county high school..."

"Good, the chemicals I need are **, **, and **. I'll write down the names and quantities for you. Go to your uncle and get these chemicals, then bring them to Zhang Lao San's blacksmith shop," Qin Hai took out paper and pen from his bag, wrote down some names, and handed them to the short one.

At this point, the young men had no choice but to follow orders. They hoped Qin Hai could create a miracle for them and turn the situation around. The short one took the paper from Qin Hai and ran towards the county high school.

After sending off the short one, Qin Hai called out, and the remaining people carried the farm tools to the blacksmith shop, led by the leading farmer. The blacksmith shop was in a row of bungalows, and a sign outside read "Zhang Lao San."

"Old San, I have something to bother you with," the leading farmer called out.

"Hey, what are you buying this time? ... Hmm, why so many people?" Zhang Lao San came out of the house, saw so many people standing outside, each holding farm tools, and was taken aback.

The farmer named Man Gu stepped forward and briefly explained the situation. Zhang Lao San took the rolled spade from Man Gu, examined the blade, and said, "Hmm, it's indeed good steel, a pity... but even if it's quenched again, it's a bit of a stretch to say it can cut bricks."

"Master Zhang, whether it's a stretch or not, can I try first? With such good steel, if the quenching is done well, cutting ordinary red bricks shouldn't be a problem," Qin Hai stepped forward and said.

Zhang Lao San looked Qin Hai up and down and said, "You're the young man who knows quenching? Where did you learn it?"

Qin Hai replied, "I graduated from the provincial agricultural machinery technical school and learned a bit about quenching there."

"Ha ha," Zhang Lao San laughed, "Learned in school, good, good. A young bull doesn't fear the tiger. I have a furnace, anvil, and water here. Show me what you can do, let this old blacksmith see."

His words were full of disdain, but his attitude was still friendly. Quenching, while not difficult, is not easy either. The easy part is that it involves heating and then immersing in water. The difficult part lies in the temperature control, and the quality of quenching depends on the operator's judgment of the temperature.

From Zhang Lao San's perspective, Qin Hai was probably an overconfident student who had learned a bit of the basics in school and wanted to show off. He believed that Qin Hai would certainly do the quenching, but the quality would be far inferior to his own. He himself couldn't make these tools capable of cutting bricks, so Qin Hai's claim was just a joke.

Qin Hai knew his age was a disadvantage, and to gain respect, he could only show his skills. He thanked Zhang Lao San and took the spade head into the blacksmith shop.