Article comprising a metal substrate and a channel in the metal substrate and method for producing same

An article having:

• a metal substrate;
• a channel defined by a wall encasing the channel in the metal substrate;
• wherein the channel has an opening at a surface of the article;
• wherein a cross section of the channel has a local width maximum (5) between a base (7) of the channel and a contact plane (1) when measured at a widest section of the cross section of the channel;
• wherein the contact plane (1) is defined as the plane corresponding to a secant that runs through two contact points of a circle having a radius of 3 mm disposed on the opening of the channel from a perspective of the cross section of the channel;
• and
• wherein a region proximal to the wall of the channel has a heat-affected zone having an altered grain size structure as compared to a grain size structure of the metal substrate which is not heat affected;
• a first heat-affected zone disposed proximal to the opening of the channel;
• wherein a ratio of a smaller average statistical grain size of the first heat-affected zone compared to an average statistical grain size of the metal substrate which is not heat affected is ≤1:2;
• and
• a second heat-affected zone disposed proximal to the channel at a lowest point vertically of the cross section of the channel or at the cross section of the channel;
• wherein the second heat-affected zone has a thickness of 0.1 μm to 3000 μm;
• and
• wherein a ratio of a smaller average statistical grain size of the second heat affected zone disposed proximal to the channel at the lowest point vertically of the cross section of the channel compared to the average statistical grain size of the metal substrate which is not heat affected is ≤1:1.2;
• and
• wherein a ratio of a greater average statistical grain size of the second heat-affected zone as compared to the smaller average statistical grain size of the first heat affected zone is ≥2:1.2.