A method for forming at least two separate three-dimensional articles through successive fusion of at least two separate regions of a powder bed, which parts correspond to successive cross sections of the three-dimensional regions, said method comprising the steps of: providing at least one model of said three-dimensional regions; applying a first powder layer on a work table; directing a first energy beam from a first energy beam source over said work table causing said first powder layer to fuse in first selected locations according to the corresponding at least one model to form a first cross section of said three-dimensional regions, where said first energy beam is fusing a first region of a first three-dimensional article to be formed with parallel scan lines in a first direction and a second region of a second three-dimensional article to be formed with parallel scan lines in a second direction; fusing at least one of said scan lines in said first region in said first direction immediately before fusing at least one of said scan lines in said second region in said second direction so that scanning of the two adjacent lines in a single region is interrupted by scanning at least another scan line in at least another region of another three-dimensional article to be formed; applying a second powder layer on the at least partially fused first powder layer; directing the energy beam over said work table causing said second powder layer to fuse in second selected locations according to the corresponding at least one model to form a second cross section of said three-dimensional regions, where the energy beam is fusing said first region with parallel scan lines in a third direction and said second region with parallel scan lines in a fourth direction; and fusing at least one of said scan lines in said first region in said third direction immediately before fusing at least one of said scan lines in another region in said fourth direction, wherein said first and second regions are provided in two separate three-dimensional articles; wherein two consecutive scan lines for a single three-dimensional article and single layer are separated by a predetermined time interval. providing at least one model of said three-dimensional regions; applying a first powder layer on a work table; directing a first energy beam from a first energy beam source over said work table causing said first powder layer to fuse in first selected locations according to the corresponding at least one model to form a first cross section of said three-dimensional regions, where said first energy beam is fusing a first region of a first three-dimensional article to be formed with parallel scan lines in a first direction and a second region of a second three-dimensional article to be formed with parallel scan lines in a second direction; fusing at least one of said scan lines in said first region in said first direction immediately before fusing at least one of said scan lines in said second region in said second direction so that scanning of the two adjacent lines in a single region is interrupted by scanning at least another scan line in at least another region of another three-dimensional article to be formed; applying a second powder layer on the at least partially fused first powder layer; directing the energy beam over said work table causing said second powder layer to fuse in second selected locations according to the corresponding at least one model to form a second cross section of said three-dimensional regions, where the energy beam is fusing said first region with parallel scan lines in a third direction and said second region with parallel scan lines in a fourth direction; and fusing at least one of said scan lines in said first region in said third direction immediately before fusing at least one of said scan lines in another region in said fourth direction, wherein said first and second regions are provided in two separate three-dimensional articles; wherein two consecutive scan lines for a single three-dimensional article and single layer are separated by a predetermined time interval.