Melt-pool motion, temperature variation and dendritic morphology of Inconel 718 during pulsed- and continuous-wave laser additive manufacturing: A comparative study. (5th April 2017)

• Record Type: Journal Article
• Authors: Li, Simeng; Xiao, Hui; Liu, Keyang; Xiao, Wenjia; Li, Yanqin; Han, Xu; Mazumder, Jyoti; Song, Lijun
• Is Part Of: Materials & design. Volume 119(2017)
• Page Start: 351
• Page End: 360
• Publication Date: 2017-04-05
• Subjects: Laser additive manufacturing -- Pulsed laser -- Numerical simulation -- Melt pool motion -- Cooling rate -- Microstructure; Materials -- Periodicals; Engineering design -- Periodicals; Matériaux -- Périodiques; Conception technique -- Périodiques; Electronic journals; 620.11
• DOI: 10.1016/j.matdes.2017.01.065
• Languages: English
• ISSNs: 0264-1275

Abstract

Graphical abstract: Abstract: Pulsed-wave laser additive manufacturing offers a number of advantages, such as a lower heat accumulation, a higher cooling rate, finer microstructures and improved mechanical properties over continuous-wave laser additive manufacturing. However, how pulsed laser acts on the melt pool motion, thermal field and hence microstructure is not clear. In this work, a three-dimensional transport model utilizing the level set method is developed to simulate the transient melt pool motion, heat/mass transfer and fluid flow for pulsed-wave laser additive manufacturing. A boundary restriction on the fluid velocity along the liquid/gas interface is employed to confine the liquid flow within the melt pool. The simulated melt pool geometry and temperature are compared with experimental measurements. Moreover, melt pool geometry/motion, temperature variation, and their influence on the microstructure of fabricated samples using both pulsed- and continuous-wave lasers are analyzed. It is found that pulsed-wave laser additive manufacturing features a rounder shaped melt pool, a periodically heartbeat-like motion of the melt pool and a doubled cooling rate. The higher tilt angle of the solidification front results in a dendrite growth direction more tilted to the laser scanning direction and the higher cooling rate results in finer columnar dendrites. Highlights: A three-dimensional model was developed for pulsed-wave laser additive manufacturing. The transient melt pool motion and thermal behavior were investigated. High tilt angle and doubled cooling rate result in tilted and refined columnar dendrites.