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Lecture

WEB Effects of HIP on Microstructure and Residual Stresses of AISI M50 produced by LPBF

Wednesday (23.09.2020)
15:40 - 15:55 S: Structural Materials 1
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Laser powder-bed fusion (LPBF) enables the production of difficult-to-machine materials with near-net shape and complex geometries. The components of tool steels produced by LPBF, even using high preheating temperature, tend to show residual porosity, cracks and high residual stresses. Residual stresses, caused by complex thermal cycles in LPBF process, lead to distortion of the components. Therefore, the method to release the stresses, meanwhile keeping the precision of component geometry, is of great importance for understanding.

Hot isostatic pressing (HIP) is able to densify components and to modify their microstructure. At the same time, HIP furnace with rapid cooling can alleviate thermal stresses, warping or cracking during quenching, compared with conventional quenching.

In this study, the microstructure evolution of additive manufactured AISI M50 after HIP and conventional post treatment is compared. Samples are produced by LPBF. Partly, they were conventionally heat treated by annealing, quenching and tempering, partly using a HIP-device with integrated quenching facility. The microstructure is characterized by optical microscopy, scanning electron microscopy employing energy-dispersive X-ray spectroscopy and X-ray diffraction (XRD) analysis. The residual stresses are measured by XRD method. The results present the residual stresses and the evolution of matrix and carbides after different heat treatments.

 

Speaker:
Siyuan Qin
RWTH Aachen University
Additional Authors:
  • Simone Herzog
    RWTH Aachen University
  • Dr. Anke Kaletsch
    RWTH Aachen University
  • Prof. Christoph Broeckmann
    RWTH Aachen University