Returning to 1949, I decided to hand it over to the state.

The two quickly went upstairs.

As Jiang Fan walked through the corridor of the factory office on the second floor of the small white building, his head was down, his mind racing, trying to figure out how to break down the manufacturing process of gas cylinders in the simplest and most understandable way. Suddenly, he heard a heated discussion coming from the meeting room where the meeting had been held yesterday:

"...If this thing could actually be built, and we could just fire a shot directly at Chiang Kai-shek's turtle-shell position...damn, that would be much easier to take down!"

Jiang Fan stumbled, feeling embarrassed, and quickly hurried to the third floor.

He dared not listen any longer, fearing that if he stayed even a second longer, those veterans who had fought their whole lives would come up with some outrageous ideas about the tactics and strategies of this thing.

Just as Zhou Chunsheng had said, the third floor was extremely quiet.

This is a fairly spacious classroom. Several rows of long wooden benches are placed against the wall, and there is a blackboard directly in front.

Zhou Chunsheng was clearly familiar with the place; as soon as he entered, he went straight to the window and opened the curtains.

The afternoon sunlight streamed in, instantly brightening the entire classroom.

Zhou Chunsheng turned around, placed his hands on the windowsill, and asked with some anticipation:

"Engineer Jiang, is this place suitable?"

Jiang Fan nodded, said nothing more, and walked directly to the blackboard.

He took half a piece of white chalk from the chalk trough, drew a horizontal line on the blackboard, and then turned to look at Zhou Chunsheng.

"Perfect, absolutely perfect."

"Engineer Zhou, I'm going to explain this process to you now. You absolutely must memorize it!"

Zhou Chunsheng immediately stood up straight.

After all, Lao Li personally ordered him to cooperate with Jiang Fan, and his inherent meticulousness as a technician was fully brought out.

He walked to the first row, crossed his left arm over his chest, and gently rested his right fingertips on his chin, his eyes fixed on the blackboard, waiting for Jiang Fan to continue.

Seeing that Zhou Chunsheng was focused, Jiang Fan turned around, picked up his pen, and quickly wrote several large characters on the blackboard:

The Complete Manufacturing Process of Gas Cylinders

Next, he drew three large sections below with chalk:

1. Material preparation and cutting

2. Stamping and stretching forming

3. Welding, assembly and flaw detection

After finishing writing, Jiang Fan turned around and tapped the first line with chalk.

"First of all, let's talk about the materials. A gas cylinder is essentially a high-pressure container filled with extremely compressed gas at extremely high pressure. If the steel used for the cylinder is not strong enough, the consequences of a rupture would be unimaginable."

He quickly drew a diagram of the stress-bearing cross-section of a cylinder on the blackboard and continued:

"Therefore, high-strength steel plates must be used as raw materials, and according to standards, HP295 special steel plates are the most suitable..."

The words had barely left his mouth when Zhou Chunsheng frowned slightly and couldn't help but interrupt:

"Engineer Jiang, wait a minute. HP295? I've never heard of this model before. It seems there's no corresponding steel grade in Ansteel's current steel product catalog, is there?"

Uh……

Jiang Fanxin blurted it out again.

HP295 is a national standard set by the National Standardization Committee in later years. Where did this thing come from in 1949?

However, since he has the backing of studying abroad, it's easy to cover it up.

Jiang Fan remained expressionless, his mind rapidly converting the physical parameters of modern steel into standards for this era, and explained:

"Oh, HP295 is what they call it when I was abroad."

"In layman's terms, it's actually a low-alloy high-strength structural steel with a carbon content of around 0.2% and a manganese content of around 1%. A little silicon is added during smelting to refine the grains."

"Our factory has limited resources right now and can't specially open a furnace to smelt this kind of special steel. So, it's perfectly feasible to use the high-quality carbon steel that our military factory uses to make artillery shell casings instead."

After all, it's not like building a space rocket where it just needs to withstand pressure.

After hearing the ingredient ratio, Zhou Chunsheng nodded thoughtfully.

"If it's just high-quality carbon steel, the blast furnace can fully meet the requirements. But what about the thickness? How thick should the steel plate be?"

Jiang Fan quickly recalled the data for ordinary household gas cylinders from later generations and replied:

"Foreign-made special steel plates generally only need a wall thickness of 2.5 to 3.0 millimeters, but we are using carbon steel instead, which is slightly weaker. For absolute safety, the thickness needs to be increased. Let's set it at 3.5 millimeters."

"Understood." Zhou Chunsheng memorized the parameters. "You can continue."

Jiang Fan continued drawing on the blackboard.

He first drew a large rectangle to represent the entire rolled steel sheet, and then marked several circular cutting lines inside it with dotted lines.

"This involves material preparation. We first cut the entire high-strength steel plate into regular circular blanks to serve as the base of the tank. The diameter of each blank is about 30 centimeters."

"Zhou, remember this step is extremely precise. If the circle is not cut perfectly round or has burrs on the edges, the subsequent stretching process will definitely be unevenly stressed. At best, the can wall will become thinner; at worst, it will tear, and the entire piece of material will be scrapped."

"Does your factory have a shearing machine that can cut such thick steel plates?"

When the topic turned to machinery and equipment, Zhou Chunsheng immediately nodded, rattling off names as if they were his own treasures:

"Yes, there is an old-fashioned heavy-duty shearing machine made in the Soviet Union in the second stamping workshop. The blade is well maintained, but whether it can achieve the roundness accuracy you mentioned, we'll have to go to the workshop to get it and test it later to find out."

"Okay, as long as we have the equipment, that's fine." Jiang Fan immediately moved on to the next step:

"The second step is stamping, which is the core step in turning a flat, round steel plate into a three-dimensional tank."

"After slightly heating the cut round blank, put it on a press for deep drawing and stretching to stretch the flat steel plate into a bowl-shaped hemisphere with an arc. This is half a can."

Jiang Fan specifically drew a key point with chalk: "It is important to note that stretching causes the metal to work harden and become brittle. Therefore, an annealing process must be performed between each stretching operation to eliminate internal stress, restore the plasticity of the steel plate, and then proceed with the next stamping."

When it comes to this basic knowledge of metal heat treatment, Zhou Chunsheng understands it immediately without any questions.

Jiang Fan continued:

"After stretching, we process the bottle neck at the top of the upper half of the tank. This is the most crucial sealing component of the entire gas tank."

"A bottle neck base with internal threads must be made at the opening. There cannot be the slightest misfit, otherwise, if the high-pressure gas leaks out, the whole thing will be lost."

Upon hearing this, Zhou Chunsheng frowned deeply, clearly mentally rehearsing the practical details of the process.

"The bottle neck thread? Our factory is even short of ordinary standard parts right now. Where can we find large taps and dies that can machine this kind of high-pressure valve?"