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Study of solidification behaviour and mechanical properties of arc stud welded AISI 316L stainless steel

Abass M. H., Alali M. S., Abbas W. S., Shehab A. A.

Journal of Achievements in Materials and Manufacturing Engineering

2019

Vol. 97, nr 1

5--14

Purpose: This paper aims to investigate the impact of arc stud welding (ASW) process parameters on the microstructure and mechanical properties of AISI 316L stainless steel stud/plate joint. Design/methodology/approach: The weld performed using ASW machine. The influence of welding current and time on solidification mode and microstructure of the fusion zone (FZ) was investigated using optical microscope and scanning electron microscope (SEM). Microhardness and torque strength tests were utilised to evaluate the mechanical properties of the welding joint. Findings: The results showed that different solidification modes and microstructure were developed in the FZ. At 400 and 600 A welding currents with 0.2 s welding time, FZ microstructure characterised with single phase austenite or austenite as a primary phase. While with 800 A and 0.2 s, the microstructure consisted of ferrite as a primary phase. Highest hardness and maximum torque strength were recorded with 800 A. Solidification cracking was detected in the FZ at fully austenitic microstructure region. Research limitations/implications: The main challenge in this work was how to avoid the arc blow phenomenon, which is necessary to generate above 300 A. The formation of arc blow can affect negatively on mechanical and metallurgical properties of the weld. Practical implications: ASW of austenitic stainless steel are used in multiple industrial sectors such as heat exchangers, boilers, furnace, exhaust of nuclear power plant. Thus, controlling of solidification modes plays an important role in enhancing weld properties. Originality/value: Study the influence of welding current and time of ASW process on solidification modes, microstructure and mechanical properties of AISI 316 austenitic stainless steel stud/plate joint.

Single crystals deformed along the basal slip system

Mikułowski B., Boczkal G.

Archives of Metallurgy and Materials

2009

Vol. 54, iss. 1

197-203

Zn-Ti single crystals of three different chemical compositions grown by the Brigman method were investigated. The microstructure of the materials was determined by scanning electron microscopy. The chemical composition of the matrix and of the second phase was also investigated. The second phase was identified as an intermetallic phase Zn16Ti exhibiting a strongly anisotropic distribution in the matrix. Transmission electron microscopy and electron back scattering diffraction showed that the [1120] direction in the matrix is parallel to the [100] direction in Zn16Ti phase. Sample orientation allowed on the deformation to ϒ=0.2 only in one slip system (0001)<112>. Mechanical properties (critical resolved shear stress and hardening coefficient in the range where easy slip operates) were obtained on the basis of compression test. Investigations were made in the temperature range of 77 K to 513 K and at two strain rates of 10-3 s-1 and 10-4 s-1.

Badano monokryształy Zn-Ti o trzech składach chemicznych, wyhodowane metodą Brigmana. Mikrostruktura materiałów była obserwowana przy użyciu skaningowego mikroskopu elektronowego (SEM). Badano także skład chemiczny osnowy oraz określono wydzielenia drugiej fazy. Faza ta została zidentyfikowana jako faza międzymetaliczna Zn16Ti, która wykazuje stałą zależność krystalograficzną względem osnowy. Badania wykonane na transmisyjnym mikroskopie elektronowym (TEM) oraz przy użyciu techniki EBSD pokazały, że kierunek [1120] w osnowie jest równoległy do kierunku [100] w fazie Zn16Ti. Orientacja badanych próbek pozwalała na zadanie deformacji postaciowej do wielkości ϒ=0.2 przy aktywności tylko jednego systemu poslizgu (0001)<120>. Własności mechaniczne (krytyczne naprężenie ścinające KNS oraz współczynnik umocnienia w zakresie działania łatwego systemu poślizgu ΘA) wyznaczano na podstawie próby ściskania. Badania prowadzono przy temperaturach w zakresie od 77K do 513K, przy dwóch prędkościach odkształcenia; 10-3 s-1 oraz 10-4 s-1.