Grain size control in laser based additive manufacturing of metallic articles

A method of additively manufacturing an alloy turbine disk having a first rim portion with a first grain size and a second hub portion with a second grain size smaller than the first grain size, the method comprising:

• forming a layer of alloy powder on a build platform;
• forming a first fused rim region of the layer of alloy powder with the first grain size by scanning the first fused rim region with a laser at a first laser power and a first scan speed;
• forming a second fused hub region of the layer of alloy powder with the second grain size by scanning the second fused hub region with the laser at a second laser power and a second scan speed, wherein the second laser power is lower than the first laser power and/or the second scan speed is faster than the first scan speed;
• and
• repeating the process in a layer by layer fashion until the alloy turbine disk is formed.

An additively manufactured alloy component comprising:

• a first portion formed of an alloy and having a first grain size;
• and
• a second portion formed of the alloy and having a second grain size smaller than the first grain size;
• wherein the first portion is formed by additive manufacturing and the second portion is formed by deformation processing and wherein the two portions are joined during additive manufacturing of the first portion.