CARBON STEEL · SQUARE & RECTANGULAR TUBE

Q235B Karbonstål firkantet rør
GB/T 6728 Cold-Formed Welded Hollow Section

Sterk, straight and easy to weld — the workhorse square and rectangular hollow section for steel structures, stativer, frames and machinery.

STANDARD: GB/T 6728 KARAKTER: Q235B TILGJENGELIG STØRRELSE TILGJENGELIG

AVKASTINGSSTYRKE

≥235 MPa

STREKKSTYRKE

370–500 MPa

SIZE RANGE

20×20–200×200

01 · PRODUKTOVERSIKT

Q235B square and rectangular hollow sections are cold-formed from hot-rolled strip and longitudinally welded to GB/T 6728. The section is square to tight corners, straight and torsion-resistant, delivering predictable strength for structural and mechanical use at a very competitive cost.

WHY CHOOSE Q235B TUBE

Ett materiale, én klasse – kun Q235B, no mixed chemistries in the batch. Uniform wall thickness, clean weld seam, precise outer dimensions and cut-to-length service for every order.

02 · NØKKELFUNKSJONER

Square Precision

Sharp, even corners and straight sidewalls improve joint fit-up and speed up frame assembly.

High Strength-to-Weight

Closed hollow section gives excellent bending and torsional stiffness per kilogram — lighter structures than open profiles.

Easy Welding

Low carbon Q235B welds cleanly in all positions — joints are strong and free of hard spots.

Consistent Wall Thickness

Roll-formed from controlled strip, wall and corner thickness stay uniform along the full length.

Seaworthy Packing

Bundles steel-banded and weather-protected, safe for long sea freight to any destination.

Cut-to-Length Service

Any length from 1 m til 12 m, precise mitre or square cutting available for ready-to-use parts.

03 · KJEMISK SAMMENSETNING (rollebesetningsanalyse, %) — Q235B

Element	C	Og	Mn	P	S
Maks innhold	0.20	0.35	1.40	0.045	0.045

Note: Verdiene er maksimal kasteanalyse i prosent. Mill testsertifikater følger med hver batch.

04 · MEKANISKE EGENSKAPER (Base Metal)

Eiendom	Verdi	Testmetode
Yield Styrke (ReH)	≥ 235 MPa	GB/T 228.1
Strekkstyrke (Rm)	370 – 500 MPa	GB/T 228.1
Forlengelse (EN)	≥ 26 %	GB/T 228.1
Charpy Impact (20 °C)	≥ 27 J	GB/T 229
Weld Seam	Flattening test — no crack	GB/T 246

STREKKSTYRKE — VANLIG KARAKTERSAMMENLIGNING

Q235B Tube (370–500 MPa)SPEKTER

Q355B (470–630 MPa)HØYERE

05 · FYSISKE EGENSKAPER

TETTHET

7.85 g/cm³

SMELTEPUNKT

≈ 1490 °C

ELASTISITETSMODUL

200 – 210 GPa

TERMISK EKSPANSJON

≈ 12×10⁻⁶ /K

06 · FELLES SPESIFIKASJONER

Section	Størrelse (mm)	Veggtykkelse (mm)	Lengde (m)
Firkantet rør	20×20 – 100×100	1.5 / 2.0 / 2.5 / 3.0 / 4.0	6 / 12
Firkantet rør (Large)	120×120 – 200×200	4.0 / 5.0 / 6.0 / 8.0 / 10.0	6 / 12
Rektangulært rør	20×30 – 150×200	1.5 – 10.0	6 / 12
Flate	Møllefinish; galvanisert, painted or oiled on request