Process for production of articles made of gamma-prime precipitation-strengthened nickel-base superalloy by selective laser melting (SLM)

Abstract

A process for the production of crack-free and dense three-dimensional articles made of a gamma-prime precipitation-strengthened nickel-base superalloy, comprising more than 6 wt.- % of [2 Al (wt. -%) + Ti (wt. -%)], by selective laser melting (SLM) comprises the steps of: a) providing an SLM apparatus (10) with an SLM control unit (19); b) providing a three-dimensional sliced model (SM) of said article with calculated cross sections, which is passed to and stored in said SLM control unit (19); c) preparing powder of said gamma-prime precipitation-strengthened nickel-base alloy material, which is needed for said SLM process; d) preparing a powder layer (18) with a regular and uniform thickness on a substrate plate (13) of said SLM apparatus (10) or on a previously processed powder layer (14); e) melting said prepared powder layer (18) by scanning with a focused laser beam (17) an area corresponding to a cross section of said article according to the three-dimensional sliced model (SM) stored in said control unit (19); f) lowering the substrate plate (13) by one layer thickness; g) repeating steps from d) to f) until reaching the last cross section according to the three-dimensional sliced model (SM); wherein for said melting step e) the laser power, focus diameter (d) of the focal spot (20) and scan speed of said focused laser beam (17) are adjusted to obtain heat dissipation welding.

Description

technical field [0001] The invention relates to the technique of producing three-dimensional objects by means of selective laser melting (SLM). It refers to the process of producing crack-free and dense three-dimensional objects made of γ' precipitation-strengthened nickel-based superalloys by selective laser melting (SLM). Background technique [0002] Gamma-prime (γ') precipitation strengthened nickel-based superalloys with a combined fraction of Al and Ti exceeding about 5 wt.-% are known to be very difficult to weld because of their microcrack susceptibility. [0003] In: B. Geddes, H. Leon, X. Huang: Superalloys, Alloying and performance, ASM International 2010, pp. 71-72, the authors describe the weldability line for superalloys approximately as [twice the Al concentration (wt.-%) + Ti concentration (wt.%)] < 6.0, which means that Ni-based superalloys with more than 6wt.-% [2Al (wt.-%) + Ti (wt.-%)] Limited to difficult-to-weld materials. Solidification and grain...

AI Technical Summary

Problems solved by technology

Due to the low thermal conductivity of the powder bed, the heating and cooling of the powder bed takes a lot of time, which leads to a significant reduction in the productivity of the SLM process

In addition, expensive heating equipment and insulation are required as well as modification of the process chamber

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