Carburizing is only one of the most representative surface treatment processes, and the nitriding process is similar to the metal surface infiltration process in that world.

Legend has it that once upon a time there was a blacksmith who made a very sharp sword. His secret is that he uses horse urine to quench the sword, an ingenious method that is said to be able to complete both the quenching and nitriding processes at the same time. If this anecdote is objectively true, then Andrei thinks that if the blacksmith gets a sweaty horse, he will even be able to complete carbonitriding in the quenching process.

Blood in the urine can contain carbon.

The veracity of the rumors didn't matter to Andre, and the Son of the Abyss couldn't recommend to the dwarves this kind of "earth quenching" that even he himself found incredible. In modern industry, even Andrei himself did not know what the chemical preparations and concentration ratio of quenching solution contained. Taking a step back, even if he knew the exact recipe for the carburizing solvent, even if it was barely formulated under Andrari's conditions, its purity would be far from the strict requirements of industrial preparation.

In ancient times, the carburizing method was not very complicated, plant ash, toner, mud and other things can be mixed as carburizing preparations, they are wrapped in steel workpieces and then pasted with some yellow mud and heated in the furnace to make excellent surface high-carbon steel tools. As for what kind of heat can make the quality of the sword reach the peak, it all depends on the master's craftsmanship.

André did not know the exact process of this, and under his guidance, the dwarves tried to use coke powder mixed with animal fat, egg whites, and yellow clay, and then applied to iron tools and heated in a furnace. The hardness of the finished product is then tested with a steel chisel and hammer, and dwarves who are familiar with the nature of steel can naturally feel the superiority of this process over the hundred steels. Not only is the efficiency far superior to the latter, but the key is to maintain the superior toughness of the shaft of the sword while maintaining the surface hardness! This can greatly improve the service life of steel tools.

The dwarves who discovered this were once again enthusiastic about this new process, and André nodded to himself with the scientific way he used the elven wooden scale to weigh the specific gravity of coke and solvent and record the comparison. If the direction of the Children of the Abyss's guidance was correct, the Greystone Clan could even perfect a new technique that would have taken tens or hundreds of years to fully grasp in the past in a matter of ten or even a few years.

This scientific method of teamwork and rigorous documentation is many times more efficient than the traditional master-apprenticeship of dwarves and elves. As long as the documented plan is tried, even a novice can quickly master this new carburizing process, and Garuda even has a unique advantage in controlling the heat during the carburizing process, so that his comprehension of it is far ahead of all the dwarven masters. In the development of this new process, which is all on the same starting line, the Flame Demon's sensitivity to temperature undoubtedly makes the amount of carbon infiltrated during the heating process of the carburizing work under his control more stable, and when there is no thermometer as a reference, Galouda's fuzzy sensing of the flame element becomes the most effective means of observation.

As for the other carburizing method, the forging carburizing method, in fact, the carburizing process in the former process is changed to an open carburizing process that is heated and forged at the same time. This technique is more dependent on the mastery of the hand experience of the craftsmen, and requires a lot of experience accumulation, and the hundred steels of the dwarven masters are a relatively inefficient method of forging carburizing. But this carburizing process is significantly more difficult to quantify certain parameters, and every master may give a different answer to the question of how many strokes should be struck, with varying degrees of force, and in what kind of heat. In addition, forging may allow the penetration depth of carbon to reach the axis of the sword, although this can greatly increase the hardness of the weapon, but if it is not applied well, it will also cause the finished product to become more "brittle" and easy to break.

After the "stuffy steel" process of Flame Demon wrapping and heating through yellow mud could no longer further improve the performance of the knife itself in a short period of time, Andre put the process of local quenching on the agenda.

Compared with the ratio of carburizing penetrant, it is even more difficult to accurately quantify the parameters in the quenching process. As far as Andrei knows, since ancient times, some blacksmiths have had certain requirements for the aqueous solution of the quenching medium, although there are rumors such as horse urine that may be more false, but there are also legends such as the use of spring water, oil and even blood quenching. In addition to these quenching media, which are used for element infiltration, the more important thing in quenching is the temperature change of the unfinished product itself. This change is entirely empirical, and the Dwarves quenched the "Fire Demon's Hand" by dipping it in spring water when it was hot, causing the surface temperature of the hammer to drop rapidly, and removing it when the temperature of its inner core was still high. The cooling surface is tempered by internal high temperatures and then immersed in water again to cool down, and so on to complete the closest heat treatment process to perfection in their centuries of experience – high surface hardness and axial toughness.

However, this passive local quenching is more suitable for heavy weapons such as hammers, and the Shadow Blade in Andrei's design is limited in thickness, so it is not suitable for local quenching in this way. Unless a master quenching master can cool down the process to within a few tenths of a second, which requires repeated cold water cooling, this is simply too much for man. The Children of the Abyss had no choice but to borrow part of the principles of the modern local quenching process - local heating.

The process of local heating has already been mechanized and electronic in the era known to Andre, and only a sufficiently precise high-frequency current heating machine is required, and the local heating of the workpiece can ensure that the error of the heating part is kept at the millimeter level, and the accuracy of its temperature control is a luxury that the children of the abyss dare not think of.

Despite the lack of high-tech machinery, André has managed to find a way to work in the wizarding world through collective efforts. It is made of mud mixed with water-rich ice spring water and mountain top permafrost, which is extremely repelling to the fire element. Wrap the blade and back of the prototype, exposing its blade, and then heat the blade of the prototype weapon with Garuda's highly condensed high-temperature magic flame to a temperature that the Firefiend and Dwarven Masters deem appropriate, and then dip it in cold water and quench it. Such a quenching process is equivalent to quenching and hardening only the cutting edge. This was repeated and then the hardness of the chopping steel axe was tested and the best solution was finally obtained.

At this point, the half-finished long knife, which had been folded and forged repeatedly and had been engraved with shadow and earth runes, was used by the masters for its first carburizing and quenching tests to determine and correct possible differences in the properties between meteorite and mortal iron. Fortunately, the process was very smooth, and after the first carburizing process, the magic iron long blade showed far better toughness and hardness than ordinary iron. In the process, the surface of the long knife appeared with a strange gray and smoke-like pattern that had appeared in previous attempts. Then, at Andre's suggestion, in order to improve the overall hardness and toughness of the blade, the fire demon carried out the whole knife normalization. Finally, during the normalizing process, the blade is protected by a mud rich in water elements, and the blade is quenched again.

After tempering, the blade has turned a dark gray, and the faint gray pattern has long been integrated into it. The blade is formed between the blade and the blade, and after the normalization of the blade is completed, the stress contraction of the blade and the back of the blade naturally causes the whole knife to pull and form a wonderful arc, just like the well-known Toei knife in the world that Andre knows.

Similar to this Shadow Blade, the iconic curved blade of most Toei knives was not originally intended by the bladesmiths. However, due to the large difference in the mechanical properties of the blade and the blade and the back, it is finally formed naturally due to excessive shrinkage of the blade and back after heat treatment. It is not because of its beauty that it adopted this curved design at the beginning, but because of the extreme pursuit of its physical properties, this wonderful arc has finally become an iconic feature of national culture!

When this magical longknife, which incorporates the new craftsmanship of many dwarven masters, is "finally baked", its fantastic appearance first conquers the aesthetics of everyone present, including the elves. Andre is about the height of the whole knife, the blade is four fingers wide, and the thickest part is one and a half fingers, there is a beautiful burnt pattern dividing line between the blade and the blade, the whole long knife is like the child of the abyss two months ago, exuding a faint black mist, and the purple metallic luster in the sun is attracting everyone's extremely enthusiastic eyes.

Taking the two-handed blade from the Dwarven Master, Andre handed it to the four-armed snake demon who was eager to try it, "Try it, Mora, and see if it works better than your beast fangs." ”

"Your Highness, my long knife is only made of the molars in the bones of ordinary desolate beasts, a complete desolate beast corpse is enough to arm an Abyssal Collar snake demon army, how can it be compared to your unique transcendent demon blade?"

Despite her humble words, the snake demon tried to swing the long knife that was longer and heavier than its fangs in the middle of the crowd, her fangs were very similar to the shape of this magic sword, in Mora's hands, this magic longsword was more difficult to grasp than her two weapons that had been used for many years, and she needed to use both hands to wield it with ease.

And the dwarves, who are good at joining in the fun, are eager to verify what kind of extreme performance the new craft can bring to the weapon. They placed several thick stakes on the iron felt, and pointed the edge of an axe, which had been tested by chopping, into a notched one, encouraging the snake demon to test the power of the sword. Some people think that this kind of over-the-top testing will cause some damage to the magic sword, but the children of the abyss think that if the quality is not up to par, it is better to return to the furnace and reforge it early!

With Andre's approval, Mora raised the long knife above his head with both arms, and the black qi that had originally escaped was tightly attached to the blade at this moment! The muscles in the snake demon's waist and abdomen contracted violently, and the muscles around his chest and shoulders instantly tensed, and the magic sword slashed at the steel axe blade above the iron felt with a faint purple brilliance and a low humming sound.

There was a crisp sound of metal, and everyone's eyes widened in disbelief - the steel axe of the dwarven warrior and the planks on the iron felt were slashed in two by the snake demon! Mora, in the crowd, looked at the magic sword in his hand in a daze, and the dwarven craftsmen cheered as if they had found a new continent.

André and Marcellion crouched on the ground together and picked up the splinters that had been cut by the blade, and the corners of the axe and felt were so flat that some of the bubbles and impurities could even be seen in the iron felt casting.

"It seems that the reason it's so sharp isn't just because of the new craftsmanship mastered by the master blacksmiths. The druid motioned to the son of the abyss to look at the broken piece of wood in his hand, and the slightly charred section was not known because of the burning of the fire element or the erosion of dark magic.

"Let's call it 'Demon Sword-Burning Shadow'!" André gave the magic sword a name that he thought was very much in line with its traditional style, "Mora, you must use and maintain it well in the future. ”

Oversized blades are not suitable for beginners, and while there has been no shortage of more exaggerated long weapons throughout history, they have either been used in horse battles or in group formations. None of these weapons are suitable for individual combat, and probably only a snake demon warrior like Mora, who is close to two meters tall and twice as long as this number, can control this extra-long Qimen weapon.

"Your Highness...... This!?" The sudden decision of the Children of the Abyss made the snake demon who was still immersed in the splendor of the sword a little overwhelmed, such a powerful weapon naturally made her feel inexplicably excited, but such items should be controlled by the leader of the tribe because of their preciousness. She never thought that His Highness would keep this unique magic long knife for herself!

"To you, it's yours, do you think that such a long blade can be easily wielded by the whole Andrari!?"

"Your Highness......!" At this moment, the snake demon was so at a loss that he didn't know what to say.

......

Many years later, when the "Cast Hand" of the Fire Demon King and the "Scorching Night" of the Sword Queen were invincible on the battlefield of Garlandia, countless legends were written. It is known that these two heirlooms were originally just the first time that the children of the abyss, who had been considered legendary all their lives, showed their superior wisdom in martial arts, and tried their hand at instructing a group of dwarven blacksmith masters.