Microstructure case study of LENS(tm) processed cylinder from AISI H13 steel

Abstract

This paper presents the microstructure analysis of laser cladding process fabricated cylindrical specimens from AISI H13 steel, produced parallel to parts of tools for deep drawing, by LENSTM 850-R, OPTOMEC, equipment. The specimens are with dimension Ø14,5x15 mm, made by 1000W laser power moved with 60 mm/s traverse velocity, formed on substrate from low carbon commercial steel. The showed macro- and microstructure is typically to that presented in investigation from several authors, related to build parts by additive deposition of layers from molt bead created by laser and direct addition of powder in melt. The LENS formed structure of dense body is similar to welding with non equilibrium solidification of melt by fast cooling. The microstructure is non uniform in all direction in body, influenced from LENS process, as well as from non uniform temperature fields, cooling rate and different direction of heat transfer. Generally microstructure consists from dendrites and equiaxial grains built from melt or by overlapping of deposits influenced areas and heat influenced zone. The microstructure is formed of: (1) martenzite obtain with phase transformation from primary solidified austenite and (2) rest intercellular ferrite, rich of alloying elements Cr and Mo.