Effects of Rare Earth Elements on Microstructure and Mechanical Properties of H13 Die Steel

The effects of rare earth (RE) elements on the carbide distribution, transformation temperature, and mechanical properties of H13 die steels after annealing were systematically investigated by scanning electron microscopy, electron probe microanalysis, and transmission electron microscopy. The results indicated that the addition of RE elements is helpful in increasing the fraction of the disrupted M23C6 carbide along the grain boundaries, hindering the migration of grain boundaries and improving the crack-formation and expansion resistance of the carbides in the tensile process. With the addition of RE, the Ac3 temperature increased by 11.4 °C and the diffusion of carbon atoms was pinned during the austenitizing process. Moreover, the carbides were modified by rare earth elements, and RE-inclusion promoted the transition of brittle-type failure to ductile-type failure. Therefore, the impact energy, hardness, and ultimate tensile strength improved significantly in the RE-modified H13 die steels.

The Effect of Rapid Solidification on Microstructure and Corrosion of Advanced Biomaterial Co-Cr-Mo-C Alloy

In this research, the microstructure and corrosion properties of rapidly solidified Co-Cr-Mo-C alloy as an advanced biomaterial alloy were studied. The use of rapid solidification casting method represents significant changes in not only the amount of formed e-HCP phase, which is strongly influenced by rapid solidification, but also in electrochemical behavior and solidified structure. In this research, rapid solidified Co-Cr-Mo-C alloy is studied using OM, SEM, EDS, XRD, and dynamic potentiostate. Co-alloy ingots were melted into an induction furnace filled by argon gas and casted into a V-shape sand and chill copper molds to prepare rapid solidified samples and its properties were measured in different cooling rates. The microstructure examination demonstrating the structure of alloy is mainly consist of columnar dendritic structure with the distribution of carbides within primary and secondary dendrites arms and finer dendritic structure along with modified carbide distribution will be achieved by rapid solidification. This structure will improve alloy’s corrosion behavior and reduces its corrosion rate when it is tested in Ringer’s solution as an electrolyte.

Characterisation of Electrode Drying Effect on the Tungsten Carbide Hardfacing Microstructure

This study addresses characterization of ED (electrode drying) effect on WC hardfacing welding microstructure. Medium carbon steel blade which used as CD (continuous digester) blade to mix up sulphuric acid together with ilmenite ore in a digester tank as a major part of production. Microstructure of WC hardfacing, elemental composition alongside hardness analyses are executed to investigate the effect of ED (electrode drying). The ED (electrode drying) effect on microstructure and hardness values of WC hardafcing coating are characterized by SEM (scanning electron microscope) analysis and micro-Vickers hardness tester correspondingly. Results revealed that ED (electrode drying) effect less significant in the larger carbides at overall coating zone. However, the absence of ED (electrode drying) led to distribution of uniform smaller carbide in non-carbide zone. The uniform carbide distribution increases the hardness of the WC hardfacing coating.

Development of multi-value circulation based on remanufacturing

Remanufacturing is an industrial process that turns used products into new ones with the same quality, functionality, and warranty as new products; it is a critical element for realizing a resource-efficient manufacturing industry and a circular economy. Remanufacturing may involve adding new and better functionality to used products, such as adding more wear-resistant materials to the surface or new sensor systems. Remanufacturing has been undertaken for products such as: automobile parts, machinery, photocopiers, single-use cameras, furniture, and turbine components, etc. It is generally superior to material recycling in terms of energy and material savings. Our project aims to develop technologies necessary for the promotion of remanufacturing and to establish a cooperative network related to remanufacturing. As technical development items, our aim is to develop methods to assess the reliability of parts/components, develop technologies to restore deteriorated metal surfaces of used products, introduce production management methods for remanufacturing, and design a circulation system to retain the added values of products. In this paper, we introduce an outline of the project and present some preliminary results. This paper shows the possibility to quantitatively evaluate the carbide distribution (size and density) of the carburized surface of a gear, and also shows the potential to repair materials exposed to a high-temperature oxidative atmosphere by Pr-Ir coating technology.

Comparing fast inductive tempering and conventional tempering: Effects on microstructure and mechanical properties

Induction heating processes are of rising interest within the heat treating industry. Using inductive tempering, a lot of production time can be saved compared to a conventional tempering treatment. However, it is not completely understood how fast inductive processes influence the quenched and tempered microstructure and the corresponding mechanical properties. The aim of this work is to highlight differences between inductive and conventional tempering processes and to suggest a possible processing route which results in optimized microstructures, as well as desirable mechanical properties. Therefore, the present work evaluates the influencing factors of high heating rates to tempering temperatures on the microstructure as well as hardness and Charpy impact energy. To this end, after quenching a 50CrMo4 steel three different induction tempering processes are carried out and the resulting properties are subsequently compared to a conventional tempering process. The results indicate that notch impact energy raises with increasing heating rates to tempering when realizing the same hardness of the samples. The positive effect of high heating rate on toughness is traced back to smaller carbide sizes, as well as smaller carbide spacing and more uniform carbide distribution over the sample.