Method for manufacturing a work roll by laser cladding

A method for manufacturing a hot rolling mill roll by laser cladding a reusable steel axe substrate having a rotational symmetry axis with a metal coating external layer, the metal coating external layer having a work tool steel composition, the method comprising:

• rotating the reusable substrate around the rotational symmetry axis;
• effecting a laser cladding on the rotating substrate, by forming a melt pool on a surface of the rotating substrate by a laser beam as a laser-induced melt pool and affixing the coating layer by feeding a powder material into the laser-induced melt pool to form a coated substrate;
• and
• submitting the coated substrate to a post-cladding thermal treatment,
• wherein the composition for the metal coating external layer comprises 0.5-3.5% C, 2-18% Cr, 0.5-7% Mo, 0.5-8% V, 0.2-7% W, 0-5% Nb, 0-1% Ti, 0.5-2% Mn, 0.2-3% Si, and 0-3% Ni, a remainder being Fe and inevitable impurities,
• wherein a preheating of the substrate is performed due to a coating head combining induction heating with a laser cladding process,
• wherein a cladding rate is in a range from 2.35 kg/h to 18 kg/h, and
• wherein the external coating layer comprises multiple added coated sublayers and has a total thickness between 1 and 30 mm, a thickness of each single external coating sublayer being between 0.1 and 2.5 mm,
• wherein the method further comprises:
• selecting a composition for the metal coating external layer that comprises nitrogen in a range 200-2500 ppm, so as to increase abrasion resistance and in which a sum of atomic contents (mass %) of MC carbides forming elements, selected from a group consisting of Ti, Nb, and V, +3/8 of a sum of atomic contents (mass %) of M23C6 and/or M2C forming elements, selected from a group consisting of Mo, W, and Cr, is lower than a sum of atomic contents (mass %) of interstitial elements C and N, +0.01, so as to achieve homogeneous hardness for a multilayer coating;
• and
• drying or heating the powder used for cladding, controlling strictly ambient humidity, and performing the cladding process under a controlled protecting atmosphere so as to obtain a final hydrogen content in the metal coating external layer lower than 1 ppm, permitting suppression of cracks.