Free Web NovelChapter 437: Chapter 243: Forging and Inheritance
"We should proceed to the quenching step now."
Old George motioned for Lin Yu’an to follow him to a large iron barrel filled with black liquid beside the forge.
"This is oil," Old George explained. "For steel like 5160, oil quenching is suitable. The cooling speed of oil is slower and gentler than that of water, making it less likely to crack the blade."
He lit another small gas furnace specifically used for heat treatment, the flame making a "whooshing" sound.
"Quenching is the art of timing." He clamped the knife blank and slowly fed it into the flame. "You need to heat the blade precisely to the critical temperature of ’austenitization’. For 5160 steel, this temperature is about 845 degrees Celsius."
"How do you know when it’s ready?" Lin Yu’an asked.
"With your eyes, and also with a magnet." Old George picked up a natural magnet hanging on an iron wire. "When the steel is heated to the critical temperature, it temporarily loses its magnetism. See?"
He took the red-hot knife blank out of the furnace; the magnet showed no reaction when it was brought near.
"But just checking the magnetism is not enough. The ideal state is when the color is a degree brighter than the ’non-magnetic point’, a bright cherry red."
Lin Yu’an nodded, then put the knife blank back into the furnace, watching closely. A few seconds later, he swiftly pulled it out!
"Perfect, now is the time!"
With a swift and steady motion, he plunged the entire red-hot knife blank, edge facing down, straight into the oil barrel without the slightest shake!
"Sizzle——!!!"
Accompanied by a violent sound, the black quenching oil boiled instantly, and a thick white smoke mixed with a pungent smell rose into the air!
The whole process took only a second or two.
He let the knife blank sit in the oil for over ten seconds, then took it out. By now, it had completely cooled, pitch black, as if it had returned from hell!
He picked up an old steel file and scraped it forcefully against the blade.
"Clang!"
The steel file slid across the blade like it was scraping glass, producing a crisp sound, and left no marks.
"It’s done." A satisfied smile appeared on Old George’s face. "Now, it’s as hard as a bone, but also as brittle as a biscuit."
"So, we need the final step, tempering." He placed the quenched knife blank into what looked like a household oven, setting the temperature and time. fɾēewebnσveℓ.com
"Bake it at 200 degrees Celsius for two hours. This process will release the enormous stress created during quenching, allowing it to retain high hardness while regaining its necessary toughness, thus achieving a true balance of strength and flexibility." free𝑤ebnovel.com
"Once the tempering is complete and it cools down," Old George turned around, his eyes full of approval, "this piece of iron will truly come to life. Then, you can use the belt grinder, progressively from coarse to fine, to bring out its true edge, and grind it into your final artistic creation."
Lin Yu’an nodded, the entire heat treatment process like a sacred ritual that left him feeling thrilled.
During the two-hour tempering wait, he did not rest. Like a tireless machine, he continued his work, successfully forging two more flawless dagger blanks. Each strike of the hammer made his skills more refined and confident.
When the oven made a light "ding" sound, the tempering was finished.
Old George opened the oven door and, using thick fireproof gloves, removed the knife blank that had cooled to room temperature. After enduring a trial of 200 degrees Celsius, the blade’s surface displayed a faint, uniform straw-yellow hue, a sign of successful tempering.
"Now," Old George handed the knife blank to Lin Yu’an, with a tone of solemn fulfillment, "go ahead, give it its final edge."
Lin Yu’an returned to the old belt grinder. But this time, his mindset was completely different. If the previous rough grinding was done out of caution for possible quenching failure,
then the current fine grinding was out of meticulous carving for an art piece about to be born. He replaced the sandpaper with a 240-grit belt and started the machine.
"Buzz——"
The belt rotated at high speed, emitting a low, deep hum.
With both hands gripping the handle, he gently pressed the heat-treated and extremely hard blade onto the belt.
"Sizzle——"
A string of fine, bright sparks flew out like fireflies.
This time, he felt much more resistance than during annealing. He had to use more force to grind delicate traces on the hard steel surface.
His movements were slower and steadier than before. His eyes were fixed on the line where the blade met the belt, each movement measured in millimeters. He constantly reminded himself of Old George’s advice: Better slow than making a mistake.
From 240 grit, to 400 grit, then 600 grit, 800 grit...
He systematically switched to finer belts, and layer by layer, the rough grind marks on the blade’s surface were covered and smoothed.
The straight spine line of the blade became more distinct and three-dimensional under the meticulous polishing, while the main edge surfaces on either side showed a smooth satin sheen.
The workshop was filled only with the monotonous hum of the belt grinder and Lin Yu’an’s rock-steady breathing.
Old George didn’t interrupt him, simply standing by with his hands behind his back, observing silently. What he saw didn’t seem like a newcomer on his second day of apprenticeship, but rather a seasoned artisan immersed in his craft for decades.
