X70

Alloy Steel

X70

Line pipe steel. (API 5L; equiv API 5L X42 L290). Nominal values—confirm mill certificate.

Chemical Composition (%)

C	0.22
MN	1.2
P	0.03
S	0.03

Mechanical Properties

Tensile:≥415 MPa;Yield:≥290 MPa

Applications

管线钢。,Pipe

Available Forms

Carburizing (case-hardening) steel with low carbon core for toughness and a hard, wear-resistant surface after carburizing. Used for gears, camshafts, pinions, spline shafts, bushings and transmission parts subjected to fatigue and surface wear.

Uses

Typically normalized (880–920 °C, air cool) or carburized (900–930 °C) for case-hardening grades, then quenched and tempered at 150–200 °C. Carburize 900–930 °C, direct/intake quench, temper 150–200 °C; useful case depth 0.5–1.5 mm.

Heat Treatment

Weldable with standard procedures; preheat may be needed for thick sections or higher-carbon/ alloy grades. Protect from decarburization during heating (controlled atmosphere or protective coating). Machine the core stock before surface hardening; leave grinding allowance for the hardened case.

Precautions

API 5L X70 / API 5L X42 L290

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X70