Electric resistance welded steel pipe, method for manufacturing the same, and automotive structural member

By optimizing the shrink-shrink rolling process and composition, resistance-welded steel pipes that meet a specific size ratio were prepared, which solved the problem of insufficient torsion fatigue resistance in the prior art, and achieved significant improvements in high machining and torsion fatigue resistance. They were suitable for automotive structural components.

CN115243808BActive Publication Date: 2025-08-12JFE STEEL CORP
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Patent Information

Application Number
CN202180020600.2
Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Priority Date
2020-03-18
Filing Date
2021-03-15
Publication Date
2025-08-12
Estimated Expiration
2041-03-15

AI Technical Summary

Technical Problem

The torsion fatigue resistance of existing resistance-welded steel pipes is insufficient, and cannot meet the requirements of high machining and torsion fatigue resistance of automotive parts.

Method used

By optimizing the loading position and heating temperature of the steel pipe in the shrink-shrink rolling process, we ensure that the wall thickness difference and arc length of the weld area and the base material area meet a specific proportion. Combined with the appropriate shrink-shrinkage ratio and heating conditions, welded steel pipes that meet specific sizes and components are prepared.

Benefits of technology

It improves the machiningability and torsion fatigue resistance of resistance-welded steel pipes, and is suitable for automotive structural components after bending, especially stabilizers, which significantly improves its service life under torsional stress.

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Abstract

The present invention relates to an electric resistance welded steel pipe having excellent workability and torsional fatigue resistance and a method for manufacturing the same. The electric resistance welded steel pipe 1 comprises a weld region 3, which is an area within ±10 degrees in the pipe circumferential direction from an electric resistance weld seam 2 formed along the pipe length, and a base material region 6 outside the weld region 3. The pipe has an r value of 1.0 or greater in the pipe length direction, and a minimum wall thickness Ts of the weld region 3. (MIN) (mm) and the average wall thickness Tb of the base material area 6 (Ave) (mm) difference (T b(Ave) ‑Ts (MIN) ) and the arc length W (mm) of the inner surface of the pipe in the weld area 3 satisfy the following formula (1), the maximum wall thickness Ts of the weld area 3 (MAX) (mm) and Tb (Ave) (mm) satisfies the following formula (2). H / W≤0.10…Formula (1) Ts (MAX) / Tb (Ave) ≤1.05…Formula (2).
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