The Effect of Seven Etching Solutions used for the Differentiated Visualization of Complex Microstructures in Low-Alloyed Cast Iron

For numerous steel grades, detailed descriptions of different etching techniques and etching times for microstructural analysis are available. However, there are only few reference works for low-alloyed cast iron. Particularly for complex microstructures with combined fractions of bainite, ferrite, pearlite, retained austenite, carbides and martensite, there are only few detailed collections. In addition, the effects of the etchants are rarely investigated for the same image section. Therefore, this study will exclusively compare identical microstructural regions and the effect of different etchants on them. Two specific sample areas were selected in a low-alloyed cast iron and the effect of both surface removal etching and tint etching reagents on them was examined under a reflected light optical microscope and a scanning electron microscope. The results of the study have shown that some etchants for complex microstructures are only suitable in case potentially present phases are already known. However, the combined use of two etching solutions in particular, led to a very detailed and highcontrast image, capable of revealing and resolving microstructures with a variety of phases.

Bifilm Inclusions in High Alloyed Cast Iron

Continuous improvement in the quality of castings is especially important since a cast without defects is a more competitive product due to its longer lifecycle and cheaper operation. Producing quality castings requires comprehensive knowledge of their production, crystallization process, and chemical composition. The crystallization of alloyed ductile iron (without the addition of magnesium) with oxide bifilm inclusions is discussed. These inclusions reduce the quality of the castings, but they are a catalyst for the growth of spheroidal graphite that crystallizes in their vicinity. The research was carried out for cast iron with a highly hyper-eutectic composition. Scanning electron microscopy and EDS analysis were used in the research. A detailed analysis of the chemical composition was also carried out based on the spectrometric method, weight method, etc. Based on the obtained results, a model of spheroidal graphite crystallization near bifilm inclusions was proposed. The surface of the analyzed graphite particles was smooth, which suggests a primary crystallization process. The phenomenon of simple graphite and bifilm segregation towards the heat center of the castings was also documented.

Application of the optimally alloyed cast irons in order to increase the durability and to ensure the cost reduction of mining and metallurgical products

The article shows the relevance of the use of alloyed cast iron in mining and metallurgical engineering. The article discusses the technologies for producing naturally alloyed cast iron. For working bodies and friction units of mining machines, such as pumps, coal pumps, hydrocyclones, crushers and mills. The main type of wear for them is abrasive. To increase the wear resistance of cast iron the production of cast iron has not been sufficiently studied yet. Although the use of cast iron in a complex alloyed with manganese, silicon, chromium, titanium and vanadium has been studied. The article studies the influence of manganese, titanium and vanadium on the mechanical properties and performance of machine parts and products of mining and metallurgical production in contact with high-temperature and highly abrasive media. The rational content of titanium and vanadium in gray cast irons is established in the range of 0.05-0.1%, which ensures their heat resistance and increases their wear resistance. The content of these elements can be increased to 0.07-0.12%. Bushings made of this cast iron have the required wear resistance and can increase the operational reliability of the equipment in the conditions of mining and metallurgical production. They also replace non-ferrous metals, as well as products obtained by powder metallurgy methods.

Study on bonding properties between arc surfacing layers and 1045 steel substrate using pull-lift test method

Three kinds of surfacing layers of the austenitic steel, niobium alloyed steel and hypereutectic high chromium alloyed cast iron were prepared on 1045 steel substrate by arc surfacing process with self-shielding flux-cored wires. The bonding strength between surfacing layers and the substrate was tested by pull-lift test method. The experimental results show that the bonding strength between austenitic steel surfacing layer and the substrate is the highest up to 549.1 MPa, and the fracture location is near the fusion line with quasi-cleavage fracture characteristic. The bonding strength between the surfacing layer of niobium alloyed steel and the substrate is 314.4 MPa and the fracture mainly occurred at the bottom of the surfacing layer, which also presents quasi-cleavage characteristic. While the bonding strength between hypereutectic high chromium alloyed cast iron surfacing layer and the substrate is as low as 170.7 MPa and the specimen ruptures along the fusion line with brittle fracture characteristic. The bonding properties between surfacing layers and the substrate are directly related to the compositions and microstructures near the fusion line.

Application of Alloyed Cast Iron to Increase the Durability of Products of the Mining and Metallurgical Industry

The article shows the relevance of the use of alloyed cast iron in mining and metallurgical engineering. The use of cast iron alloyed with titanium and vanadium has not been sufficiently studied for the working bodies and friction units of mining machines, such as pumps, coal scoops, hydrocyclones, crushers and mills. They have the main abrasive type of wear. This work considers the influence of titanium and vanadium on the mechanical properties. The performance indicators of parts of mining machines and metallurgical products in contact with high-abrasive and high-temperature environments is also considered. The optimal content of titanium and vanadium in gray cast iron in the range of 0.05-0.1% is set. This provides the required strength properties of the components, while increasing their heat resistance. Bushings made of this cast iron have the required wear resistance and can improve the operational reliability of equipment in mining and metallurgical industries.