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Leçon 3 · classe 12+
Materials: steel, aluminium, wood, plastic
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Material choice = half the project: strength, weight, price, workability, corrosion. STEEL — strongest, cheapest, heavy and rusts (St37 standard, V2A stainless). ALUMINIUM — 3× lighter, no rust, weaker (AlMg3, 7075 aerospace). WOOD — living, strong along grain, breathes, burns (oak hard, spruce construction). PLASTIC — easy casting, insulator, UV-aging (PA nylon, PVC pipes, ABS).
- ●V2A stainless = 12%+ chrome, St37 rusts: know where it goes
- ●Wood splits along grain: fasten across the growth direction
- ●“Lighter” doesn’t mean “weaker”: carbon beats steel at ¼ weight
🔩 German steel is marked not by “quality” but purpose: St = construction, E = hardening, X = stainless. Read the grade — understand the part’s purpose.
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