If you ask a physicist: No. It violates the laws of thermodynamics (perpetual warmth is impossible without an energy source).
Medieval texts describe a test: A sheet of the finest silk was draped over a stack of 50 brass coins. A blade of ordinary Damascus steel would cut 10 coins. A blade of Fuladh al Haami was said to cut the silk, all 50 coins, and the stone table beneath—without losing its edge. Beyond physics, Fuladh al Haami occupies a massive space in Islamic Alchemy (Kimiya). The alchemist Jabir ibn Hayyan (Geber) theorized that metals were composed of "Sulfur" (the principle of combustibility) and "Mercury" (the principle of ductility). fuladh al haami
Al-Biruni, the great Persian scholar, wrote of a sword presented to the Caliph in Baghdad: "It was called 'The Protector.' When drawn at night, it glowed faintly red along the edge, as if the sun lived within the steel. No moisture clung to it; no rust could claim it." Perhaps the most coveted property of Fuladh al Haami was its alleged ability to self-sharpen. In military lore, a warrior wielding a blade of Fuladh al Haami could cut through chainmail, and with each strike, the micro-serration of the steel would realign itself. If you ask a physicist: No
We live in an age of stainless steel and ceramic blades, yet we have never replicated the supposed warmth of the Ardent Steel. Perhaps that is for the best. In a world of disposable commodities, a sword that never cools and never dulls belongs to the realm of legend. A blade of ordinary Damascus steel would cut 10 coins
Unlike normal steel, which has a specific gravity of ~7.8 g/cm³, some fragments found near Merv (modern-day Turkmenistan) have recorded densities of nearly 8.2 g/cm³, suggesting a metallic composition we cannot replicate today without electric arc furnaces.
If you ask a historian: Yes, but metaphorical. The legend was used to sell expensive swords.
Sufi mystics later adopted the term as a metaphor for the perfected soul. A Fuladh al Haami heart is one that is hot with divine love (never growing cold with apathy) yet hard as steel against injustice (never bending to tyranny). To this day, in some Persian poetry, a brave warrior is described as having "a skeleton of Fuladh al Haami." The lost art of Fuladh al Haami follows the trail of the Mongol invasion of the Khwarazmian Empire (1219–1221). When Genghis Khan's hordes swept through Persia, they specifically targeted the Khassa (the royal armories and foundries).