In this research, the thermal analysis of additive fabrication by DMLS method has been investigated. In the DMLS method, the Metal powder is melted by a Laser heat source and finally a solid t hree dimensional piece is formed This analysis was performed by finite element method in Abaqus software. L aser heat distribution is considered Gaussian. T he mechanical and thermal properties of the powder are considered as a function of melting temperature. Finally, the results obtaine d by the finite element method are compared with previous re searches. The effects of Laser speed and power on temperature distribution have also been investigated.

In this work, the effects of manufacturing parameters on the microstructure and densification of iron powders processed by Direct Laser Sintering were investigated. A specific energy parameter E, which expresses the energy input per volume of tire sintered layer, was defined and used to evaluate the impact of the parameters on the densification and the attendant micro structural features. The results show that the sintered density is an exponential function of the defined Specific energy. With increasing the energy input up to 2kj/mm3, the densification rate is relatively high. Here, the microstructure consists of bin pores (.5-1mm) and elongated ferrite grains. The densification rate will be decreased if the energy input exceeds 0.2 kJ/mm3 With intensifying the energy over 0.8 kJ/mm3, the formation of horizontally oriented cracks is likely to occur while the deflsit1 remains almost constant.

Nature of additive manufacturing processes dictate Direction-related properties to the final parts and this degree of anisotropy is highly dependent on process parameters and machine setup. Therefore, properties in such materials should be known in any Direction. There are several methods including destructive and non-destructive techniques for specifying mechanical properties in parts. Using ultrasonic testing, as a nondestructive method, in order to determine elastic constants for rocks, woods, composite and wrought materials indicative of its reliability and validity, as well as its repeatability. In this paper, 9 independent elastic constant for orthotropic additively manufactured Direct Metal Laser Sintering (DMLS) parts are determined from longitudinal and transverse ultrasound velocities via contact ultrasonic testing for different manufacturing process parameters. This work also carried out comparisons between mechanical properties of as-built parts in three principle Directions, as well as ultrasound wave velocities.

Optimization of process parameter is one of the ideal goals in Laser Sintering. The results of this process were measured as out-put parameters like: density, micro hardening, macro hardening, tension, roughness, stiffness, balling. In this paper, the influence of input parameter such as Laser power, scan speed, material powder and etc are surveyed on output parameter like balling affection and the thickness of a layer. Iron and copper powder were used in this experiment in order to produce a full density single layer on 5 mm depth bed powder. One of the efficient factors on this process is overlapping which has a reverse impact on the high and low pulse power. Finally a coupon was produced with the best setting.

In the present research the influences of manufacturing parameters e. g. Laser scan rate and working atmosphere on densification and microstructure of M2 high-speed steel powder via Direct Metal Laser Sintering (DMLS) were studied. Density and micro-hardness measurement experiments were performed on, produced specimens and microstructural evaluation was done with both optical and scanning electron microscopy (SEM). The result of experiments showed that the density of Laser sintered specimens decreased linearly with increasing the Laser scan rate. Furthermore, Sintering under the argon atmosphere yields higher densification than the nitrogen atmosphere. It was found that Laser sintered specimens have cellular and/or dendrite microstructure due to rapid solidification during the DMLS process. Also, the size of pores is independent to Laser scan rate, Sintering atmosphere and chemical composition.

One of the main goals of researchers in Metal powders Laser Sintering, is optimization of process parameters in order to close out the main properties of the raw materials have been produced to the piece. For this purpose, many experiments have been carried and parameters such as density, hardness, micro hardness, strength, surface finish, appearance, and residual stress have been studied. In this paper the influence of parameters such as Laser power, scanning speed, and powder material and etc. on output parameters such as penetration depth, strength, balling phenomenon is investigated. In order to produce a multi-layer fully dense parts by the process of pulsed Laser, to optimize the performance of the Laser and material parameters at first, it is necessary to single layers is investigated. Experiments carry out on free powder bed depth is 5 mm. Each piece of a single layer on the substrate with once Laser scanning powder is produced. Movement of the Laser beam on the surface produce a washer with 20mm diameter.