Strip cladding repair of continuous casting guide rolls

Failure environment and repair objective

The article by Zhang Xiangfu describes strip cladding repair of continuous casting guide rolls, which operate under repeated thermal cycling, mechanical contact, and abrasive cooling conditions. Guide rolls can fail by surface cracking, wear, deformation, and thermal fatigue. The repair objective is not only to restore dimension, but to produce a surface capable of surviving repeated casting contact and thermal shock.

Cladding design and process selection

The paper reports the use of strip cladding, longitudinal deposition, edge overlap, and carbon nitrogen strengthening with 0Cr13NiMoN overlay metal. Strip cladding is suitable for cylindrical rolls because it provides high deposition efficiency and a relatively flat bead profile. The overlap technique helps eliminate undercut and creates a continuous protective layer. The 0Cr13NiMoN system offers a balanced combination of corrosion resistance, hardness, and toughness for guide roll service.

Process element	Purpose	Control requirement
Strip electrode cladding	High deposition and good bead coverage.	Maintain strip flatness and stable feed.
Longitudinal cladding	Reduce circumferential stress concentration.	Control roll rotation and travel speed.
Edge overlap	Prevent undercut and expose weak areas.	Maintain overlap width and bead alignment.
Carbon nitrogen strengthening	Increase strength and wear resistance.	Control gas composition and dilution.
0Cr13NiMoN overlay	Balance toughness and surface performance.	Verify composition and macrostructure.

Process control points

Successful repair requires strict thermal management. The roll body is usually a forged or cast steel component, and the cladding heat input can generate high residual stress. Preheat, interpass temperature, and post weld thermal treatment must be selected according to the base metal carbon equivalent and repair thickness. Excessive dilution reduces overlay performance, while insufficient heat input causes lack of fusion. The overlap bead must not create sharp geometric notches after machining.

Quality assurance and service judgment

Quality control should include visual inspection, magnetic particle testing, hardness mapping, and machining allowance verification. Ultrasonic testing may be needed for thick repairs or when the roll carries high bending loads. The repaired roll should be inspected for bead overlap continuity, undercut, porosity, and transverse cracking. If the roll is machined after cladding, the final surface must remain within the intended overlay thickness.

Study insight

This case shows that repair welding is not a patching operation but a surface engineering task. The guide roll fails because of combined thermal, mechanical, and abrasive loading, so the repair must restore a designed surface system. The use of strip cladding, overlap, and composition strengthening is logical because it addresses both productivity and service performance. For roll repair shops, the critical lesson is to control dilution, thermal cycle, and geometry as carefully as weld appearance.