Kota Kadoi

Solidification cracking occurs easily at high welding speeds, and should therefore occur more easily during laser welding. Both the solidification behavior and thermal strain change depend on the welding speed, and therefore, the critical strain for solidification cracking must be measured to clarify the factors influencing the solidification cracking susceptibility. However, the critical strain required for solidification cracking under high welding speed conditions has not yet been determined.

Experimental investigation of the foam stabilizing factors that influence aluminum foam fabrication is crucial to improve the foaming process. Solid particles contribute to an increase of the viscosity of the liquid phase and overall foam stability. Foam stability depends on the liquid type, wettability and the shape of solid particles. Even though a poor wettable particle contributes effectively to enhance liquid viscosity, the particle leads to the collapse of the foam cell due to the poor ene

TiH2 powder has been used to fabricate aluminum foams as a blowing agent for more than two decades. The aim of this paper is to understand the detailed decomposition behavior of TiH2 powder and to control the phenomenon by a heat treatment for the fabrication of fine aluminum foams by the melt route. TiH2 powders whose qualities were different, were characterized using TG-DTA and XRD. As heat treatment factors, temperature and time were applied. We have found differences in the decomposition beh

In the welding of austenitic stainless steels, the formation of approximately 5% δ-ferrite phase is often used to decrease the susceptibility to solidification cracking. The partition coefficients of impurity elements such as phosphorous and sulfur of the ferrite phase are high, which expand the temperature range of solidification. At the same time, it is well known that the solidification cracking susceptibility increases with increasing δ-ferrite content above 20%. Thus, high δ-ferrite content

Varestraint test is one of the most-used methods to evaluate weld solidification cracking susceptibility. However, standard about the detailed test method and the evaluation method has not been clearly defined. Thus, it is required to standardize the methods of Varestraint test and the evaluation indexes in order to compare the results tested by each researcher.In this study, round-robin test of transverse-Varestraint test with GTAW was carried out under identical specimens and test conditions u

Although hot cracks frequently occur during metal additive manufacturing (AM), there are very few fundamental studies on the cracking behaviour and susceptibility. In this study, a horizontal tensile-type hot cracking test was investigated for evaluating the solidification cracking susceptibility of alloy 718 quantitatively during AM, particularly in laser powder bed fusion. The factors influencing the cracking susceptibility were also examined. The solidification cracking was reproduced by the

• Lacy ferrite could form with K-S relationship between ferrite and austenite during solidification. • Misorientation for lacy ferrite was ≤ 7° (close-packed plane) and ≤ 9° (close-packed direction). • Unidirectional solidification of austenite and ferrite accelerate lacy ferrite formation. • Two pass laser welding could control directions of preferential growth of ferrite and austenite. • Formation ratio of lacy ferrite significantly increased approximately 40 % (generally 5–10 %). The formatio

This study investigated the effect of equiaxed primary ferrite nucleation on the weld microstructure and tensile properties of two types of stainless steel solidified with primary ferrite. One was the F mode with only δ–ferrite during solidification, and the other was the FA mode with austenite formed at the end of solidification. MgAl 2 O 4 , formed after alloying of Ti, Al, and Mg and accelerated TiN formation due to the low lattice misfit of 4.88 % under their fully paralleled orientation. Pr