TY - JOUR

T1 - Stability of phase transformation models for Ti-6Al-4V under cyclic thermal loading imposed during laser metal deposition

AU - Klusemann, Benjamin

AU - Bambach, Markus

PY - 2018/5/2

Y1 - 2018/5/2

N2 - Processing conditions play a crucial role for the resulting microstructure and properties of the material. In particular, processing materials under non-equilibrium conditions can lead to a remarkable improvement of the final properties [1]. Additive manufacturing represents a specific process example considered in this study. Models for the prediction of residual stresses and microstructure in additive manufacturing processes, such as laser metal deposition, are being developed with huge efforts to support the development of materials and processes as well as to support process design [2-4]. Since the microstructure predicted after each heating and cooling cycle induced by the moving laser source enters the phase transformation kinetics and microstucture evolution of the subsequent heating and cooling cycle, a feed-back loop for the microstructure calculation is created. This calculation loop may become unstable so that the computed microstructure and related properties become very sensitive to small variations in the input parameters, e.g. thermal conductivity. In this paper, a model for phase transformation in Ti-6Al-4V, originally proposed by Charles Murgau et al. [5], is adopted and minimal adjusted concerning the decomposition of the martensite phase are made. This model is subsequently used to study the changes in the predictions of the different phase volume fractions during heating and cooling under the conditions of laser metal deposition with respect to slight variations in the thermal process history.

AB - Processing conditions play a crucial role for the resulting microstructure and properties of the material. In particular, processing materials under non-equilibrium conditions can lead to a remarkable improvement of the final properties [1]. Additive manufacturing represents a specific process example considered in this study. Models for the prediction of residual stresses and microstructure in additive manufacturing processes, such as laser metal deposition, are being developed with huge efforts to support the development of materials and processes as well as to support process design [2-4]. Since the microstructure predicted after each heating and cooling cycle induced by the moving laser source enters the phase transformation kinetics and microstucture evolution of the subsequent heating and cooling cycle, a feed-back loop for the microstructure calculation is created. This calculation loop may become unstable so that the computed microstructure and related properties become very sensitive to small variations in the input parameters, e.g. thermal conductivity. In this paper, a model for phase transformation in Ti-6Al-4V, originally proposed by Charles Murgau et al. [5], is adopted and minimal adjusted concerning the decomposition of the martensite phase are made. This model is subsequently used to study the changes in the predictions of the different phase volume fractions during heating and cooling under the conditions of laser metal deposition with respect to slight variations in the thermal process history.

KW - Engineering

KW - Alloys

KW - phase transitions

KW - Metal deposition

KW - Thermal conductivity

UR - http://www.scopus.com/inward/record.url?scp=85047350004&partnerID=8YFLogxK

U2 - 10.1063/1.5035004

DO - 10.1063/1.5035004

M3 - Conference article in journal

AN - SCOPUS:85047350004

VL - 1960

JO - AIP Conference Proceedings

JF - AIP Conference Proceedings

SN - 0094-243X

IS - 1

M1 - 140012

ER -