SSAB Strenx Tube 900MH
Product identity, test requirements and fabrication boundaries for the high-strength SSAB hollow section.
Tags: materials, steel, hollow-sections, producer-products
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Product identity and supplied form
SSAB lists 40 J at −20°C for Strenx Tube 900MH, transverse Charpy V on a 10 × 10 mm basis, with testing from 6 mm wall. Its welding guide gives 100°C maximum recommended preheat/interpass. The maximum is a welding control. Determine minimum preheat and heat input for the actual joint separately. SSAB 900MH impact footnote, SSAB tube welding guidance
Strenx Tube 900MH is SSAB's cold-formed, high-frequency-welded structural hollow section made from thermomechanically rolled steel. SSAB states compliance with EN 10219-3:2020. Preserve this product identity when ordering. SSAB: Tube 900MH
SSAB's product offer lists a 4.0–6.0 mm wall range, circular sizes 139.7–219.1 mm, square sizes 100 × 100–200 × 200 mm, and rectangular sizes 120 × 80–250 × 150 mm. These are offer envelopes, not confirmation that every wall/size combination is stocked or manufacturable. Confirm the particular combination and length in the order. SSAB: Strenx product offer
Mechanical properties and test scope
The product page specifies:
| Property | Stated requirement |
|---|---|
| Rp0.2 proof strength | Minimum 900 MPa |
| Tensile strength Rm | 930–1,200 MPa |
| Elongation A5 | Minimum 7%, with section-proportion exception |
| Transverse Charpy-V energy | Minimum 40 J at −20 °C, referenced to a 10 × 10 mm specimen |
The elongation minimum decreases by two percentage points for D/T < 15, or (B + H)/(2T) < 12.5 for rectangular/square sections. Rectangular-section mechanical tests use the longer side. Impact testing under EN ISO 148-1 is performed for thickness ≥6 mm; the stated minimum corresponds to a full-size specimen. SSAB: properties and footnotes
Illustrative stress check: a hypothetical 500 mm² effective net area carrying a uniformly distributed 100 kN axial force has nominal stress 100,000/500 = 200 MPa. Comparison with 900 MPa is not a capacity approval: the calculation omits buckling, bending, load eccentricity, connections, fatigue and required safety factors. It also assumes that 500 mm² is the applicable effective area, rather than deriving it from an actual ordered section.
Standards, certification and inspection
The accessible Strenx Guarantees PDF prints v4–2023, although its download filename contains “v3-2023.” Its tube section distinguishes HF-welded MH/MLH products from plasma-welded, quenched-and-tempered QLH products. It states CE-marking availability up to 700 MPa yield strength in that discussion. That statement does not establish CE marking for Tube 900MH. Confirm the exact documentation and applicable project requirements rather than extending a family-level statement. SSAB: Strenx Guarantees, tube section
The same guide directs inspection and reporting to the applicable material standard or datasheet unless otherwise agreed. Define special testing and required inspection documents at ordering. Separate mill certification from the qualification and inspection of the finished welded assembly. SSAB: testing provisions
For design, confirm that the selected member and connection rules cover the grade, section geometry and loading. Check local and overall instability, joint resistance and serviceability. Higher proof strength does not proportionally increase elastic stiffness or make a thinner wall equally resistant to local buckling.
Welding and heat control
Welding of Strenx, V1 US Letter 2026, explicitly includes Tube 900MH. Its maximum preheat/interpass table specifies 100 °C for this product, distinguishing it from some other Strenx grades with higher permitted values. Select the actual minimum preheat, heat input, consumables and procedure using the complete guide conditions; a maximum temperature alone cannot establish a welding procedure. SSAB: welding guide V1–2026
Qualify joint strength, toughness, distortion and fatigue performance for the actual tube and heat-affected region.
SSAB does not recommend hot-dip galvanizing Tube 900MH. Confirm an appropriate corrosion-protection route with the producer and coating supplier. SSAB: product restriction
Cutting, geometry and fabrication sequence
SSAB's tube-group guidance notes that cold forming leaves residual stresses and that cutting can cause distortion. It discusses laser, plasma and oxy-fuel routes at a family level. Plan the cut sequence, supports, inspection points and final dimensional acceptance for the actual component. Any stress-relief heat treatment requires product-specific confirmation; a general family suggestion is insufficient authority to heat a 900MH part. SSAB: Strenx tube processing guidance
Check outside dimensions, wall, corner profile, straightness, twist and seam location against the required fit and joint design. Preserve tolerances rather than treating nominal geometry as measured geometry. Holes, slots, end cuts and attachment welds can change both net section and local stress distribution. Verify the completed geometry after fabrication, not only the incoming tube.
Fatigue and service validation
SSAB's fatigue guidance emphasizes that welded-detail behavior depends strongly on geometry, imperfections and residual stresses. Base-material strength alone does not determine the fatigue benefit of a redesign. Its trailer examples illustrate design effects rather than providing Tube 900MH joint capacities. SSAB: fatigue guidance
For a lifting or transport structure, establish the actual load spectrum, stress concentrations, attachment details, weld quality and inspection strategy. Assess corrosion, impact, temperature and maintenance conditions separately. An incoming tensile certificate does not validate a fatigue-loaded assembly, an unqualified thermal operation or a connection outside the applicable design method.
Purchase and release record
Retain the exact product/form and dimensions, governing specifications and editions, certificate and traceability, test conditions and exceptions, design basis, fabrication procedures, corrosion-protection route and completed-part inspections. Record approved substitutions explicitly.
The welding guide prints V1 US Letter 2026 and the cited guarantees guide prints v4–2023. The product pages do not display a clear technical revision date; obtain current controlled documentation for procurement. This article's review date does not revise a standard or establish the provenance of any delivered material.