C90

Alloy Steel

C90

Oil country tubular goods (OCTG). (API 5CT; equiv API 5CT J55). Nominal values—confirm mill certificate.

Chemical Composition (%)

C	0.3
MN	0.5
P	0.02
S	0.02

Mechanical Properties

Tensile:≥517 MPa;Yield:379-552 MPa

Applications

油套管。,Pipe

Available Forms

Medium-carbon grade for machine parts such as gears, crankshafts, axles, connecting rods, spindles and forgings that need a balance of strength, toughness and machinability. Commonly supplied as bar, plate, sheet, tube and forging.

Uses

Austenitize at 820–870 °C (oil or water quench depending on section) and temper at 400–650 °C to the required strength/toughness balance.

Heat Treatment

Preheat and control interpass temperature when welding; post-weld heat treatment or stress relief is recommended to avoid hard-zone cracking. Use low-hydrogen electrodes. Protect from decarburization during heating (controlled atmosphere or protective coating).

Precautions

API 5CT C90 / API 5CT J55

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C90