When the fiery red high-temperature molten iron comes into contact with the scrap steel, it surges and splashes like ocean waves, boiling violently. The workers outside the safe area in front of the furnace feel a wave of rolling heat rushing towards their faces and covering their whole bodies.
This is the heat of steel.
Most of the scrap steel used in the base area comes from acquisitions. In the name of Taihang Industrial Company, scrap steel is purchased at high prices, and a scrap metal recycling industry chain similar to that of later generations has been established in Shaanxi and Shanxi. Whether it is the people in the base area, or businessmen and merchants outside the base area,
The common people are very happy to sell all kinds of scrap steel they get to Taihang Industrial Company.
As for where the scrap steel came from...
Heroes don’t ask where they come from, scrap metal doesn’t ask where it came from.
Thanks to the scrap acquisition industry chain established by Taihang Industrial Company, the electric furnace steel mills in the base area have a continuous supply of scrap steel, and the same is true for the current scrap supply of the pilot furnace.
Of course, as long as the first smelting test is successful, a positive circulation system for steel ingot supply can be established, eliminating the situation where scrap steel supply is completely dependent on external purchases.
"Stop injecting molten iron and add the main slag material and mixed flux." When the height of the molten iron in the converter reaches the limit value, and the total amount filled is about 70%, Yu Hua, who is standing in the main control room and observing at all times, immediately gives new instructions.
instruction.
After receiving the order, crane worker Sun Hong stopped dumping the molten iron, placed the iron bucket in a limited area, and then lifted the funnel containing the slag-making material and mixed solvent to the top of the converter, opened the bottom funnel, and added the slag material.
The main slag material is limestone, and the mixed solvent is raw dolomite and fluorite.
The former is used for dephosphorization and desulfurization, and is the main slag-forming agent in the converter steelmaking method. The disadvantage is that it is prone to slow melting. The latter is similar to a catalyst, accelerating the melting of lime into slag and reducing the splashing of molten steel. Both are indispensable.
.
Splashing of molten steel is no joke. If you are not careful, it may cause fatal production accidents.
The three auxiliary metallurgical materials were finally obtained after countless scientists in the metallurgical field tested them again and again, spending countless funds and efforts, and even at the cost of blood.
As the three slag-making raw materials are added into the converter, changes occur immediately inside the furnace. Under the action of high temperature and flux, the limestone mixes with the molten iron and continuously absorbs the sulfur and phosphorus elements.
In the entire steel smelting process, silicon and carbon are exothermic elements, and manganese is a beneficial element. Its content can be reduced in the molten steel, or manganese can be increased to smelt high-manganese steel. Phosphorus and sulfur are harmful elements and must be removed as much as possible.
Remove or reduce their ingredient content.
The main harm of phosphorus is to reduce the plasticity and toughness of steel, making it cold brittle, while the main harm of sulfur is to make the steel more hot brittle.
"The furnace body rotates vertically, the air separator supplies oxygen, and the oxygen lance is at a high position." Upon seeing this, Yu Hua turned to the two operators in the main control room and ordered.
There are two control stations in the main control room, one is responsible for the converter and the other is responsible for the oxygen lance. The entire test furnace has personnel with formal operating qualifications, including Yu Hua, a total of three people.
Generally speaking, the height between the oxygen lance nozzle and the surface of the converter liquid molten pool is divided into three levels: high, medium and low. The blowing effect is different. The high lance position reduces slag, the middle lance position reduces splashing, rapid decarburization, and the low lance position reduces
For the second slag, the gun position configuration is determined according to the different slag making methods.
Slag making is divided into single slag method and double slag method. Single slag method usually only makes slag once during the smelting process, and the gun position is selected to combine high + medium.
As the name suggests, the double slag method involves making two slags during the smelting process. The gun position is first high + medium, and then low + medium. The smelting process is complicated and is usually used for the smelting of silicon steel and gun steel.
The first smelting test chose the single-slag method and did not use double-slag for the time being.
After receiving Yu Hua's order, the young converter operator who had undergone heavy selection and rigorous training nodded, with a serious face, holding the joystick tightly with both hands, and slowly pushed forward, turning the converter back to ninety degrees at a rotation speed of about two degrees per second.
vertical angle.
"Buzz!" At the same time, the air separation equipment that was in the lowest power idle state gradually increased to the highest power, operated at full load, and fully supplied pure oxygen to the test furnace.
Here, with the oxygen lance directly facing the converter vertically, the young operator controls the oxygen lance to rise to the highest gun position. The three-hole nozzle is aimed at the red interior of the converter. When the working oxygen pressure displayed on the barometer reaches 8 standard atmospheres,
Then press the oxygen supply button.
In an instant, a sharp and high-frequency sound suddenly resounded through the factory and reached everyone's ears.
High-pressure pure oxygen moves forward at high speed in the metal pipe, reaching the speed of sound in an instant, and reaches the nozzle part of the Laval nozzle structure across a distance of just a few meters. Due to the sudden increase in the cross-sectional area of the air flow, the pure oxygen movement speed and pressure surge, and instantly
Increased by an order of magnitude, from hundreds of meters per second to several kilometers per second.
Forward, impact!
The three oxygen streams pierce the converter like long swords and blow on the surface of the molten iron. The pure oxygen and the high-temperature molten iron produce the most violent and direct oxidation reaction, and the temperature of the molten iron rapidly increases.
The main heat source of the oxygen converter steelmaking method basically comes from the physical heat and chemical heat of the molten iron entering the furnace. The temperature is about 1,300 degrees Celsius. With the oxidation produced by high-purity oxygen blowing, the final temperature can reach 1,700 degrees Celsius.
degrees Celsius, there is no need to supply additional heat, thus saving energy.
Compared with the current mainstream open-hearth steelmaking in the world's industrialized countries, the technological advancement of oxygen-blown furnace steelmaking is not just in terms of output.
In the test furnace, the chemical composition of the molten iron in the early stages of blowing is constantly changing. Silicon and oxygen generate silica, releasing a high amount of chemical heat. The silicon content in the molten iron decreases at a rate visible to the naked eye. Subsequently, the limestone and flux
The slag material is accelerated to melt and melt, forming a thin layer of highly alkaline slag on the surface of the molten iron.
With this layer of slag, the impurity elements inside the molten iron seem to have found a home, quickly coming together and condensing, and the thickness of the slag increases.
Time slowly passed, and after two minutes, as the silicon in the molten iron dropped to a minimum, manganese and phosphorus entered the high-temperature oxidation and exothermic stage one after another, causing the temperature of the molten iron to further increase, and controlling the molten pool temperature to around 1550 degrees Celsius.
At this point, the entire blowing process has reached the intermediate stage.
Now, the impurity elements such as silicon, manganese, phosphorus and sulfur in the molten iron have all been transformed into high-quality slag under the action of high temperature, slag materials and fluxes.
The quality of slag can objectively reflect the quality and cleanliness of molten steel. In a sense, steelmaking is about continuous slag.
"Down to the gun position, the cold cycle power reaches the highest level, and the molten iron is quickly decarburized."
In the main control room, Yu Hua raised his right hand and looked at the time displayed on his watch. Ten minutes had passed, and then gave instructions to the oxygen gun operator.
According to the dynamic mathematical model of molten steel smelting in the experimental furnace constructed by Yu Hua, after ten minutes of blowing, the internal chemical impurities of the molten iron have been converted into slag. All that needs to be done now is to convert the molten iron into molten steel!
The key to transforming iron into steel lies in the carbon content.
Steel with a carbon content of less than 0.25% is called low carbon steel. It has low mechanical properties and is generally called 'mild steel'.
Medium carbon steel has a carbon content between 0.25% and 0.65%. It has good mechanical and chemical properties and is mainly used in various mechanical parts, barrel steel, gun steel, armor steel and other special products required in the military industry.
Steel materials are all based on the extension and improvement of medium carbon steel frames, adding various beneficial elements that improve the mechanical properties of the material, such as manganese, nickel, tungsten, chromium, molybdenum, vanadium, etc., becoming what people often call alloy steel and structural steel.
In addition, silicon steel, known as the aristocrat of steel, also belongs to the medium carbon steel frame.
Steel with a carbon content between 0.6% and 1.7% is called high carbon steel, often called tool steel in the industry. It has excellent mechanical and chemical properties, but low toughness and plasticity. It is usually used as metal cutting tools, such as turning.
Knives, milling cutters, reamers, boring tools, etc.
Of course, like medium carbon steel, adding various beneficial elements can make it a high carbon alloy steel, such as high carbon tungsten steel, high carbon manganese steel, etc.
The target selected for the first smelting test is the most widely used medium carbon steel.
"yes!"
The young oxygen lance operator nodded immediately and controlled the oxygen lance nozzle to descend. Due to the lack of real-time observation equipment in the furnace, the specific position of the oxygen lance nozzle can only be estimated manually based on the descending rate of the console. Basically, it is judged by the feeling.
standard.
It's very informal, but it's practical.
After all, Rome was not built in a day. These steel plant supporting facilities and instruments must be developed step by step to have them. Reaching the sky in one step is nothing more than a dream.
In fact, in addition to the fact that the height of the oxygen lance nozzle cannot be accurately controlled, there are also problems such as the inability to dynamically and accurately measure the composition and carbon content of molten steel. Dynamic accurate measurement can grasp the composition and carbon content of molten steel anytime and anywhere. If a certain element is missing,
Then add it. If there is too much of a certain element, then reduce it. In this way, you can achieve the goal of smelting exclusive steel types.
However, the test furnace does not yet have this condition. The first smelting test completely relies on the calculation data of the mathematical model of molten steel smelting constructed by Yu Hua. If there is a big gap between the mathematical model and reality, it means that the test failed.
Here, the oxygen gun operator mentally calculated the rate of descent. He felt that the nozzle had almost dropped to the height of the shot, and then pressed the pause switch.
Above the converter, the oxygen lance nozzle, which is about five centimeters away from the lance position, continuously sprays pure oxygen at hypersonic speed, impacting the molten iron in the molten pool with a higher impact force, causing it to tumble and stir, entering the rapid decarburization stage.
Under the impact of pure oxygen, the molten iron in the molten pool surges rapidly in a clockwise direction. The internal carbon elements continuously generate carbon monoxide and carbon dioxide. Streams of brown harmful smoke emerge, travel along the exhaust pipe, and are discharged outward through the chimney.
Stuffed into Mingzhu Yulin, it has the smell of heavy industry for the first time.
This is pollution, but also...
hope!
…
Five minutes later, the temperature in the molten pool, which was in the rapid decarburization stage, reached 1,600 degrees Celsius, and the carbon content of the molten iron continued to decline, eventually breaking through the 2% critical node.
Now, the molten iron turns into molten steel.
But it's not enough!
Yu Hua's face was calm, his eyes were fixed on the converter, and the thinking computer in his mind was started, using more than 70% of the computing resources to continuously deduce the mathematical model of molten steel smelting, introducing all variable factors and related data to achieve the maximum simulation of the internal reaction of the realistic converter.
1.5% carbon content, high carbon steel range.
1.3% carbon content, high carbon steel range.
0.8% carbon content, high carbon steel range.
0.59% carbon content, entering medium carbon steel.
"Stop the oxygen supply!" The carbon content of the molten steel reached 0.55% in his mind. In an instant, Yu Hua, who raised his right hand high, suddenly lowered it and gave instructions to the oxygen gun operator.
The oxygen gun operator, who was already ready, pressed the switch without hesitation to turn off the oxygen supply.
"Buzz!" The penetrating and sharp roar of the oxygen gun when supplying oxygen disappeared, and the factory suddenly fell into a brief silence. The only sounds were the rolling of molten steel in the converter and the operation of the air separator.
The workers and soldiers who were around were stunned for a moment, and then they immediately realized what had happened. They showed excitement on their faces, and they all stood ready.
The most important moment has come!
"Tilt the furnace body, prepare the slag ball, and tap out the molten steel." Yu Hua did not delay, raised his hand to check the time, and issued new orders to the converter operator and various production groups.
The carbon content data of the mathematical model of molten steel smelting was finally fixed at 0.55%. The mechanical and chemical properties are more than 20% better than the electric furnace steel produced in the electric furnace steel plant, which can fully meet the needs of horizontal-lever diesel engine pistons, crankshafts, gears and low-bore pressure percussion barrels.
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Of course, this is a simulation calculation result, and it is not clear what the actual error value is. Yu Hua hopes that the error value can be less than 1%.
The total smelting took 33 minutes. Now, the molten steel is tapped and the prototype steel ingot is cast.
Yang Zhi and a group of Red Army soldiers stared at the test furnace. The steel bucket, commonly known as the "steel ladle", came to the molten steel outlet. It contained deoxidizer. At the same time, the converter operator controlled the tilt angle of the furnace body and the slag ball device entered
state of readiness.
The slag ball device mainly prevents large amounts of mixing of steel slag and molten steel. It was designed by the Japanese metallurgical industry in the 1970s. The structure is a sphere composed of dolomite and iron core. The technical content is average and the design is extremely exquisite. Yu Hua unceremoniously put this
The exquisite design is put to use.
At this moment, everyone was holding their breath, not even daring to take a breath.
The metal baffle of the steel tap opened, and a ball of red flame burst out like an explosion, churning upwards with great force. Before anyone could react, in just one second, hot and scalding molten steel flowed rapidly along the groove.
, enter the steel ladle located directly below.
"It's out, the molten steel is out!" Looking at this scene, the workers and soldiers at the nearest distance burst into tears and couldn't help but cry from the deepest part of their hearts.
Molten steel, symbolizing the future of molten steel, was quietly born at a historic moment.
Looking at the continuous flow of molten steel, everyone present seemed to be possessed and fell into a state of obsession. An inexplicable feeling surged from the depths of the soul and spread throughout the body. The extremely dazzling molten steel appeared in the distance.
Far more attractive than any other stunning beauty.
It is so surging and powerful, it is so bright and moving...
As soon as the news of the molten steel came out, it swept through everyone in Sancha Bay like a bombshell. The entire Sancha Bay boiled instantly. Countless workers from the Military Industry Bureau and soldiers from the First Red Division were extremely excited and celebrated the moment in their own ways.
At 10:20 am on August 3, 1937, the world's first furnace of molten steel smelted by an oxygen top-blown converter was born in Sancha Bay, Yulin, northern Shaanxi, China.
"Add slag retaining balls and prepare the round ingot mold." Yu Hua looked calm and calm, not caring about the emotions of the workers and soldiers around him. He looked through the furnace mouth and saw that the molten pool in the furnace had been reduced by three-quarters, and continued.
The release of molten steel is worthy of celebration, but anyone can celebrate, except him.
The first smelting test is not over yet.
The chief dispatcher nodded, quickly waved the flag, and conveyed his respective instructions to the slag ball production team and the molten steel casting production team.
Soon, a slag ball with a diameter of 8 cm was placed above the tap hole of the converter to block the surrounding slag. At the same time, the molten steel pouring production team on standby immediately became busy checking whether there were any problems with the round steel ingot mold.
There are 90 sets of round steel ingot molds with an inner diameter of 80 mm and a length of 2.4 meters. They are connected in parallel to improve pouring efficiency. After the casting of these round ingots is completed, they will be sent to Liushugou Industrial Zone for tempering, forging and rolling, and then converted into stainless steel.
Seamed steel pipes, after a series of treatments, become qualified standard mortar tube blanks.
After a few minutes, the molten steel was poured out, and the ladle containing two tons of bright yellow molten steel was slowly lifted by a ten-ton crane, left the converter, and came to the sky above the pouring area.
The regrouping team constantly communicated with the pouring team. The ladle gradually lowered its height and came to the top of the pouring opening. The angle was tilted and the nozzle was aligned. In an instant, the molten steel with a temperature of 1,500 degrees Celsius suddenly flowed out and entered circles along the pouring opening.
Within the ingot mold.
After two tons of molten steel were poured, the scene was extremely spectacular. Ninety sets of round ingot molds ignited with billowing flames, and the molten steel inside entered the cooling stage.
"Deputy Team Leader Yu, what are we going to do next?" Yang Zhi, who was also staying in the main control room, asked curiously when he saw the scene in the pouring area below.
Hearing this, Yu Hua responded with a smile: "When the real test results are obtained and steel is smelted, then the first smelting test passes and a 24-hour trial production is carried out. If it is iron, then it is declared a failure and the problem is found.
Revise."
Although Yu Hua knew very well that what was being smelted was steel, he had to maintain the most basic rigor before formal test results were released.
"I see, then what we are smelting must be steel." Hearing this, Yang Zhi nodded, staring at the ninety sets of round ingot molds in the pouring area, murmuring softly, full of hope in his heart.
Based on the length of each set of molds being two meters and four meters, one round steel ingot can produce four mortar barrels. The round ingot here can theoretically produce 360 barrels.
Three hundred and sixty barrels, in a sense, this is three hundred and sixty mortars!
After the joy of the first batch of molten steel flowing out, the factory once again fell into a state of expectant waiting. Everyone focused on the cooling round ingot molds, understanding that the quality of these finished products ultimately determines the success of the first smelting test.
Is it steel?
Or iron?
The molten steel in the round ingot mold cools and crystallizes, gradually forming grains. After a few hours, it is time to demould. As the first set of round ingot molds is opened, the fiery red round ingot comes into view, responsible for the final test result detection.
Two workers came forward with sledgehammers and carried out the simplest quality inspection on the red round ingot.
In this era, the easiest way to detect whether it is steel or iron is to smash it!
Pig iron will crumble and steel will deform.
"Dong dong dong!" The sledgehammer hit the surface of the round ingot hard, and a dull and powerful sound came out. The surface of the fiery red round ingot was slightly deformed, and irregular iron oxide was scattered. The body of the round ingot did not appear to be broken.
.
One hammer was not enough to seal the coffin. Under everyone's gaze, the two workers worked hard with their sledgehammers and hammered the ingot again and again.
Looking at the hammered surface of the ingot, the soldiers and workers surrounding them tried their best to remain silent and disciplined, but after a while, they could no longer bear the emotions in their hearts.