Steel making is a technologically demanding and complex process during which a significant wear occurs on the metallurgical primary operations technology and equipment. There are many factors influencing functional parts of this equipment. Namely direct external factors such as abrasive wear, adhesive wear, erosive wear, thermal fatigue, corrosion at high temperatures in combination with negative effect of fluxes and mould powders, as well as secondary indirect factors that originated during fabrication of the part, or during its previous renovation [
1,
2,
3,
4]. Diverse fabrication and inner defects are included, as well as residual stress. In order to provide for a continuous and trouble-free operation of the manufacturing process it is necessary to regularly inspect and maintain the parts and if needed replace them with new ones. Rolls play an essential role in the steel making processes with respect to steel-making on continuous strip rolling mills, processing of slabs on the hot strip rolling mill stands or rolls on the cold strip rolling mill. The task of rolls on the steel continuous casting line is apart from steel guiding, i.e., guiding continuous slab during its cooling, to shape the slab during deformation of its solidifying skin. As result of high temperatures ranging from 1250 °C to 800 °C thermal fatigue occurs on the roll surface [
5,
6]. During steel rolling process the cooling with water spray is applied in the curve section of the rolling mill. A negative factor having effect on the overall service life of rolls is also high portion of chlorine ions that contribute to origination of the so-called corrosion fatigue. The surface quality of these rolls directly influences also the quality of the rolled steel surface. Surface defects that originate on the rolls are also reflected on the surface of cast and rolled steel. In the next phase, slabs are processed on the hot strip rolling mill stands. The roll configuration in the finishing stands of hot strip rolling mills consist of two relatively small work rolls supported by two larger backup rolls [
7,
8]. Work rolls are responsible for the direct contact of the roll surface with slab during its rolling. Work rolls are exposed during service to thermal fatigue, mechanical fatigue, wear, impacts so that good thermal, mechanical and tribological properties are required for the materials employed for their fabrication [
1]. Backup rolls fall in the second group of rolls. These are the rolls with diameters of more than 1000 mm and the length range up to 3000 mm [
9]. The task of backup rolls is to support work rolls and thus prevent their bending or even breaking. Whereas temperature is not a problem (HSM backup roll surface temperature typically is 150 °C in service), mechanical stresses have a fundamental effect on roll service life. No water cooling of rolls is required, the corrosion fatigue influencing the quality of their surfaces is only small and, therefore, the corrosion fatigue is much lower. During service, backup rolls are subjected to intense compressive stresses (of the order of 1–5 GPa at the surface) while cyclic shear stresses, sometimes in excess of 500 MPa, are generated below the surface of the rolls, as presented in analyses Hertz and Belyaev [
10,
11]. In addition to mechanical stresses, backup rolls are subjected to wear, however, unlike for work rolls, the nature of the wear mechanisms is not well documented [
12,
13]. Nevertheless, two body abrasive wear from carbides and three-body abrasive wear from hard strip oxide transfer (between the work and backup roll) are believed to be the predominant mechanisms [
14,
15,
16]. Uneven roll surface finish leads to a heterogeneous load distribution on the barrel length, which causes localized plastic yielding and eventually induces cracking and spalling [
17,
18,
19,
20,
21]. One the basis of service conditions, the ideal back-up roll material should exhibit high resistance to fatigue crack initiation and propagation, high resistance to burst cracking, a uniform microstructure and properties, low strain hardening behaviour and finally, good wear resistance. Previous work [
1,
2,
3,
14] in the field of continuous casting as well as on hot rolling rolls produced exceptional results. In this particular study a fundamental approach has been adopted, which includes an investigation of back-up roll failure and the possibility of restoring its surfaces by cladding [
22]. The research in the area of renovation of backup rolls and work rolls has developed in several directions. One was to apply additive materials with higher level of plasticity and toughness during restoration by cladding using arc methods even at the cost of lower abrasive resistance and another direction was the possibility of layer hardening by precipitation. Carbide precipitation is the main strengthening mechanism and each type of carbides play different kind of roles. As well known, the fine dispersed strengthening MC carbide retards the microstructural recovery and is important for improving the creep rupture strength of steel. The popular Cr-Fe-rich carbide M
7C
3 grows easily and usually precipitates on the lath or block boundaries, which caused the migration of grain boundary and, therefore, shortened the time to the onset of acceleration creep. Here M = Fe, Cr, Mo, V, etc. Recently, Janovec [
23,
24]. Bhadeshia [
25] and Pigrova et al. [
26] have attributed considerable attention to the precipitation behaviours of carbide during long-term aging. However, there is seldom detailed investigation on the carbide evolution behaviours of low-alloyed Cr-Mo-V steels during heat treatment, such as mass fraction, chemical composition and particle size. It usually plays a key role on the stability and resistance to creep and to hydrogen damage [
27,
28,
29,
30,
31]. The disadvantage of backup rolls is their difficult restoration after they are worn out and with respect to their dimensions the cost of new rolls requires a significant investment for the mill restoration [
5,
6,
8,
9,
12,
13,
14,
15,
16,
22,
32].
The paper presents the results of the research focused on the evaluation of the quality of the four types of weld deposits of the backup rolls of the cold rolling mill. The microstructure of the clad layers, their mechanical properties and the lifetime were evaluated in rolling fatigue conditions.