Metal additive manufacturing is a molding method with a high degree of freedom because it can be created from high-strength materials using by CAD, etc. In recent years, there is a demand for metal additive manufacturing due to the demand for more complex mechanisms and shape in industrial products. However, the mechanical properties of metal additive manufacturing materials as metallic materials are not clear compared to metallic materials by melting method. In this study, two types of metal additive manufacturing (AM) materials with different lamination directions are carburized and heat treated to clarify the differences from general metallic materials and to clarify the causes. The carburized AM materials were confirmed to have a surface hardness of 550HV and a total carburization depth of 200 μm, but the amount of carburization differed depending on the orientation. In addition, when analyzed with a SEM, a metal structure was formed in an equiaxed crystal shape, and segregation of metal elements was observed.

In industrial applications, hot forging of aluminum alloy AA 6082 is carried out at 480 °C following a preheating process in an induction heater. The forged parts are then cooled down to room temperature, heated up again to apply conventional solution treatment followed by quenching and artificial aging processes. Repetitive heating/cooling steps are a significant cause of energy loss. The aim of this study was to provide time and energy efficiency by combining hot forging and solution treatment processes in a single high temperature process. To achieve this a new and improved heat treatment pattern was introduced. AA6082 parts were quenched immediately from a rather high forging temperature and artificially aged without any necessity for a second heating step and solution treatment. Mechanical properties of parts heat treated by this new pattern were than compared to the mechanical properties of parts heat treated conventionally. Heat treatment of AA6082 alloys were carried out for 30 minutes at three different temperatures (480, 510 and 540 °C) for comparison, followed by forging, water quenching and artificial aging (180°C, 8h). Mechanical properties of each sample were investigated using hardness and tensile tests. Elemental analysis and microstructural characterization were carried out using Energy Dispersive Spectrometry (EDS), Scanning Electron Microscope (SEM) and Optical Microscope (OM). Required minimum hardness for the samples after heat treatment was considered as 90 HB. This hardness value could not be obtained for the parts forged/solution treated at 480°C and 510°C. Hardness values of parts heat treated at 540°C, water quenched and aged at 180°C were higher than 90 HB.

The solution quenching process is a critical heat treatment process for aluminum alloys to obtain better strength and a homogeneous super solid solution. In this paper, the mechanical properties of Al-5%Cu-0.4%Mn in the as-quenched state are tested. The alloy, designated as ZL205 (Chinese standard), has a chemical composition similar to a 2xxx series aluminum alloy and is used for constructing large thin wall components. The ZL205A alloy shows good performance under loading at room temperature while losing its toughness and exhibiting tensile brittleness, which is unexpected at elevated temperatures (especially at 300 °C). After observing the fracture sections of ZL205A at room temperature and at 300 °C, it may be concluded that one possible reason leading to this phenomenon may be the formation of the T phase at grain boundaries. Such a hypothesis is validated and discussed with the help of SEM observations.

The heat-treating industry is in need of heat-treatment furnace materials and fixtures that have a long service life and reduced heat capacity. Failure mechanisms on the effect of prolonged exposure to carburization heat treatment have been investigated. RA330, RA602CA, 304L, 316L and Inconel 625 alloys were selected to study the anti-corrosion properties. The alloys were exposed to 0.7%C carburizing atmosphere at around 900°C for 3 months, 6months, and 12months. Based on microstructural analysis of components that were used until failure in carburization furnace application, it was found that the primary reason for failure was the excessive carburization that leads to “metal dusting” and subsequent cracking. In addition, metallographic analysis indicated that “flake offs” of Fe-Cr-Ni alloys were mainly graphite and chromium carbides. In this paper the failure analysis of industrial components will be presented. In addition, the preliminary analysis of microstructural development during long term exposure experiments in an industrial carburizing furnace will be presented. These samples were characterized using optical and scanning electron microscope and x-ray diffraction.

In the recent years, there has been a remarkable increase in the use of deep cryogenic treatment (DCT) for enhancing performance of tool steels. It is a supplementary treatment where components are treated below subzero temperatures for several cryo-soaking hours. This paper focuses on to study the effect of deep cryogenic treatment and cryo-soaking time on microstructural and mechanical properties of AISI H-13 tool steel. Deep cryogenic treatment at different cryo-soaking time (16-48 hours) were applied and tool steel performance was analyzed by using mechanical, fatigue and wear testings. The microstructural evolutions during DCT were evaluated by using scanning electron microscope (SEM). It was observed that microstructural modifications like increase in carbide density, fine and uniform martensitic structure during DCT had significantly improved properties which were influenced by cryo-soaking time.