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GOST 20295-K70
keyword GOST 20295-K70 Category Steel pipe material Related products Get a quoteGOST 20295-K70 steel grade submerged arc welded spiral seam steel pipe material, chemical composition and mechanical properties
1、 Chemical composition
Carbon (C): ≤ 0.12% (low-carbon design to optimize welding performance and reduce cold cracking risk).
Silicon (Si): ≤ 0.40% (deoxidation and grain refinement to improve material uniformity).
Manganese (Mn): 1.50% -1.80% (strengthens the matrix and supports high-strength requirements).
Phosphorus (P): ≤ 0.020% (strict control of impurities to reduce cold brittleness).
Sulfur (S): ≤ 0.006% (reduces the tendency for hot cracking and improves welding stability).
Micro alloying elements (niobium Nb, vanadium V, titanium Ti): added in small amounts to refine grain size and enhance comprehensive mechanical properties.
2、 Mechanical performance
Strength and plasticity
Yield strength (Re): ≥ 600 MPa (based on the increasing trend of K series and the performance inference of X70 pipeline steel).
Tensile strength (Rm): 750-900 MPa (refer to X70 pipeline steel standard and K-series strength increasing law).
Elongation (A): ≥ 16% (plastic deformation capacity under high pressure environment).
Resilience requirements
Low temperature impact toughness: It must meet the requirement of -40 ℃ impact energy ≥ 45 J (refer to X70 pipeline steel standard and high cold environment requirements).
3、 Manufacturing and testing requirements
Forming process
Spiral welding: Adopting double-sided submerged arc welding (SAWH) process, the weld strength and uniformity are improved.
Tolerance control:
Outer diameter tolerance: ± 0.75% (applicable to 159-820mm specifications).
Wall thickness tolerance: ± 6% nominal wall thickness (stricter than lower steel grade standards).
Testing requirements
Non destructive testing: Ultrasonic testing (UT) and X-ray re inspection of the entire pipe section, with no defects such as porosity or slag inclusion in the weld seam.
Hydrostatic test: according to the formula
P=2ST/D test for compressive performance (S is yield strength, T is wall thickness, D is outer diameter).
4、 Application scenarios
Oil and gas transportation: suitable for high-pressure oil and natural gas long-distance pipelines and deep-sea pipelines.
Industrial field: Used for high-pressure metal structures certified by Russian standards, mining pipelines in extreme environments, and other scenarios.
(Note: K70 is an inferred high-strength grade, and specific parameters should be based on the GOST 20295 standard or manufacturer's technical agreement.)
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