BAR MADE FROM MEDIUM-CARBON STEEL Russian patent published in 2006 - IPC C21D8/06 C22C38/44 

FIELD: metallurgy; production of round merchant shapes for manufacture of automobile shock absorber rods.

SUBSTANCE: bar is molten from medium-carbon steel containing the following components, mass-%: carbon, 0.42-0.50; manganese, 0.50-0.80; silicon, 0.17-0.37; sulfur, 0.020-0.040; phosphorus, 0.001-0.030; aluminum, 0.03-0.05; calcium, 0.001-0.010; oxygen, 0.001-0.015; chromium, no more than 0.25; nickel, no more than 0.25; copper, no more than 0.25; molybdenum, no more than 0.10; arsenic, no more than 0.08; nitrogen no more than 0.015; the remainder being iron and unavoidable admixtures at oxygen/calcium ratio of 1-4.5 and calcium-sulfur ratio of ≥ 0.065. Bar has non-metallic inclusions with double-layer structure- sulfide with oxide envelope; curvature of bar is no more than 0.5 mm/m; bar has plastic ferrito-pearlite structure; size of actual grain is 5-8 points; diameter of grain ranges from 10 to 30 mm; hardness is 229-255; rupture strength is no less than 660 Mpa; relative elongation is no less than 8% and relative reduction of area is no less than 35%.

EFFECT: improved machinability; homogeneous properties over entire section of bar.

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