Durehete Welding — Cr-Mo-V Bolting Steel Procedure (EN 10269)

Matched-composition low-hydrogen filler per the manufacturer welding procedure specification (WPS). Closest commercial match is a low-hydrogen SMAW electrode with chemistry tracking the parent Cr-Mo-V envelope. Procurement specification typically calls for the filler to be pre-qualified by the bolting OEM; off-the-shelf filler letter-grades do not exactly match the Ti+B microalloying of Durehete 1055.

Pre-heat 250 to 300 degrees Celsius measured at 75 mm from the weld joint on parent material. Maintain interpass temperature in the same band throughout the welding operation. Drop in interpass below 200 degrees Celsius risks hydrogen-induced cold cracking in the heat-affected zone.

SMAW or GTAW per the procurement specification. Heat input 1.0-2.5 kJ/mm. Stringer-bead technique preferred over weave to minimise heat-affected zone width. Multi-pass welding required for joints above 6 mm thickness; each pass below the previous one in temperature to control HAZ grain coarsening.

Mandatory stress-relief at 660 to 680 degrees Celsius, minimum 2 hours per 25 mm of section, furnace cool to below 300 degrees Celsius. The PWHT temperature must not exceed the original tempering temperature of the parent material (which is 660-730 degrees Celsius from the EN 10269 Q+T cycle); exceeding it would over-temper the parent and reduce its mechanical properties.

Visual inspection to ISO 5817 quality level B. Magnetic particle or dye-penetrant inspection on the cap and root pass to the procurement specification. Ultrasonic inspection on butt joints above 25 mm thickness. Hardness traverse across the weld + HAZ + parent verifies the PWHT achieved the intended tempering: hardness should not exceed 320 HBW at any point.