Inspect again for cracking or fracture.<\/li>\n<\/ol>\nCalculation & Reporting<\/h2>\n
Pass\/fail per bar with bar designation, mandrel diameter, angles and ageing conditions. Test frequency follows the product standard’s batch\/cast sampling plan.<\/p>\n
Acceptance Criteria<\/h2>\n
No fracture and no cracks visible on the outer bent surface. A single rebend failure typically triggers retesting at increased frequency on the cast; systematic failures reject the batch \u2014 common causes are high nitrogen steel or excessive cold working at the mill.<\/p>\n
Frequently Asked Questions<\/h2>\nWhy include the ageing step in the rebend test?<\/h3>\n
Strain ageing embrittlement develops over weeks at site temperature. Thirty minutes at 100 °C accelerates the same nitrogen-migration mechanism, exposing bars that would crack when re-straightened on site.<\/p>\n
What mandrel diameter should be used?<\/h3>\n
It scales with bar size and grade \u2014 BS 4449 B500B uses 4d up to 16 mm and 7d above; always take the former size from the product standard, not a generic table.<\/p>\n
Recommended Apparatus<\/h2>\n
NL Scientific manufactures the Cold Bend Testing Machine (6-50mm Dia.)<\/a> for this method. Browse the full Steel Testing Equipment<\/a> range or request a quotation<\/a> from our engineers.<\/p>\n
\n