Method for the manufacture of a compound product with a surface region of a wear resistant coating, such a product and the use of a steel material for obtaining the coating

A compound product comprising a substrate of a first metallic material giving the product the necessary strength/resistance, and a coating of wear resistant steel material applied on a surface region of the substrate, wherein the wear resistant steel material comprises a substrate for a wear surface, where the substrate has a first composition, and wherein the wear surface comprises a wear resistant steel material with a second composition, which comprises, in weight-%:

• C
• Si
• Mn
• Cr
• Ni
• Mo + W/2
• Co
• S
• N
• 0.01-2
• 0.01-3.0
• 0.01-10.0
• 16-33
• max. 5
• 0.01-5.0
• max. 9
• max. 0.5
• 0.6-10
• and, further,
• 0.5 to 14 of (V+Nb/2), wherein the contents of N, on one hand, and of (V+Nb/2), on the other hand, are balanced in relation to each other so that the contents of said elements are within an range A′, B′, G, H, A′ in a perpendicular, plane coordinate system, where the content of N is the abscissa and the content of V+Nb/2 is the ordinate, and where the coordinates for said points are:
• A′
• B′
• G
• H
• N
• 0.6
• 1.6
• 9.8
• 2.6
• V + Nb/2
• 0.5
• 0.5
• 14.0
• 14.0
• and
• max 7 of any of Ti, Zr, and Al;
• balance essentially only iron and unavoidable impurities;
• the steel material has a microstructure comprising an even distribution of up to 50 vol.-% of hard phase particles of M2X-, MX- and or M23C6/M7C3-type, the size of which in their longest extension is 1 to 10 μm, where the content of said hard phase particles is such that up to 20 vol.-% are M2X-carbides, -nitridies and/or -carbonitries, wherein M mainly is Cr, and X mainly is N, and 5 to 40 vol.-% of MX-carbides, -nitrides and/or -carbonitrides, wherein M mainly is V and Cr, and X mainly is N, wherein the average size of said MX-particles is below 3 μm, preferably below 2 μm, and even more preferred below 1 μm.

Use of a steel material produced in a powder metallurgical manner with the following composition in weight-%:

• C
• Si
• Mn
• Cr
• Ni
• Mo + ½W
• Co
• S
• N
• 0.01-2
• 0.01-3.0
• 0.01-10.0
• 16-33
• max. 5
• 0.01-5.0
• max. 9
• max. 0.5
• 0.6-10
• and, further,
• 0.5 to 14 of (V+Nb/2), wherein the contents of N, on one hand, and of (V+Nb/2), on the other hand, are balanced in relation to each other so that the contents of said elements are within a range A′, B′, G, H, A′ in a perpendicular, plane coordinate system, where the content of N is the abscissa and the content of V+Nb/2 is the ordinate, and where the coordinates for said points are:
• A′
• B′
• G
• H
• N
• 0.6
• 1.6
• 9.8
• 2.6
• V + Nb/2
• 0.5
• 0.5
• 14.0
• 14.0
• and
• max 7 of any of Ti, Zr, and Al;
• balance essentially only iron and unavoidable impurities;
• for obtaining a wear resistant surface region on a substrate of a metallic material with another, first composition, wherein said surface region preferably is a wear surface of a valve, preferably a valve in a nuclear power plant and even more preferred a valve in the primary circuit of a nuclear power plant.