20Cr square steel processing is a systematic sequence of precision operations that transforms raw 20Cr alloy billets into high-performance square-section products, tailored for applications requiring a balance of strength, wear resistance, and toughness—such as gears, shafts, structural brackets, and mechanical components. The process begins with rigorous raw material validation. 20Cr, a low-alloy steel containing 0.18–0.24% carbon and 0.17–0.24% chromium, must meet strict chemical composition and mechanical property standards. Inspectors use spectroscopic analysis to verify alloy content and visual checks to eliminate billets with surface defects (cracks, inclusions, or unevenness). Qualified billets are then cut to target lengths using band saws or plasma cutters, ensuring clean, burr-free edges to avoid issues in subsequent steps. Heating is the next critical phase. Billets are loaded into a controlled-atmosphere furnace and heated to 850–900°C—the austenitizing temperature for 20Cr. Uniform heating is essential to prevent thermal stress and ensure consistent material properties across the billet. Overheating or uneven heating can lead to brittleness or dimensional distortion, so furnace temperatures are monitored in real time. Forming shapes the heated billets into square profiles. Most production lines use rolling mills: roughing mills reduce the billet’s cross-section, intermediate mills refine the shape, and finishing mills achieve precise square dimensions (e.g., 10mm×10mm to 100mm×100mm) with tight tolerances (±0.1mm for precision grades). For custom components, open-die or closed-die forging may be employed to create near-net shapes, minimizing material waste and machining time. Heat treatment unlocks 20Cr’s full potential. Quenching involves immersing the formed square steel in oil (water is avoided to prevent cracking) after reheating to 850–880°C, hardening the material. Tempering follows: heating to 500–600°C and holding for a set duration to reduce brittleness and adjust hardness to 25–35 HRC—balancing strength and ductility, critical for load-bearing parts. Surface treatment steps include pickling to remove oxide scale from heating and rolling, followed by passivation to enhance corrosion resistance. Shot blasting may also be used to achieve a smooth, clean surface. For parts needing extra protection, galvanizing or electroplating can be applied. Machining is optional but common for blanks destined for precision components. Turning, milling, drilling, or grinding operations shape the square steel into final parts with exact dimensions and features, adhering to strict tolerance requirements. Quality control is integrated at every stage: dimensional checks with calipers/micrometers, hardness testing via Rockwell methods, tensile tests to verify strength, and metallographic analysis to confirm microstructure. Non-destructive testing (ultrasonic, magnetic particle) detects internal defects, ensuring compliance with industry standards. Finally, finished 20Cr square steel is wrapped in anti-rust material and bundled for transport, stored in dry, ventilated facilities to prevent corrosion until delivery to end-users. This process ensures the product meets the demanding needs of automotive, machinery, and construction industries.