Metallurgical describes things that belong to metallurgy: the scientific study of metals and their uses — how we take them from rock, melt and mix them, and make them stronger, lighter, or better for a job. A metallurgical laboratory tests metal. Metallurgical engineering is the university subject. The word is an adjective; it does not name the science itself (that name is metallurgy). It is a formal, technical word you meet in science, factories, and engineering, not in everyday chat.