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Copyright of Proceedings on Quality is the property of University of Zenica, Faculty of Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Gray cast iron belongs to the group of iron casts that contain graphite particles in the microstructure. Graphite particles in gray cast iron have the shape of lamellae and are connected to each other. The specific combination of properties of gray cast iron, which is satisfactory for many applications, and simple and cheap production are the main reasons for its very wide application. For many years, gray cast iron has been the most used material for making metal castings. In this paper, there are microstructure tests for different variations of alloying gray cast iron with chromium, molybdenum, and copper. The assumption is that these elements influence the formation of pearlite in the microstructure, in different combinations. [ABSTRACT FROM AUTHOR]

Steel cooling is an important technological operation because the final microstructure of the steel, and therefore its properties, depends on the cooling rate. The speed of steel cooling depends on numerous factors, one of which is the movement of the cooling media. This paper presents the results of testing the influence of mixing the cooling media on the microstructure and hardness of 23MnB4 steel. Two media that are usually used for quenching steel (water and oil) were used for the test. The samples were cooled in an unstirred media and in a stirred media with three different stirring speeds (500, 750, and 1000 rpm). The results showed that mixing the media has an influence on the microstructure and hardness of steel. Samples that were cooled in a mixed medium had a higher hardness. The mixing speed had a greater influence on the hardness in the case of cooling in water. The microstructure after cooling in the water and oil was martensite-bainite. With an increasing cooling rate, the ratio of martensite in microstructure increases. [ABSTRACT FROM AUTHOR]

Austempered ductile iron is the last addition to the group of ductile irons obtained by isothermal improvement of classic ductile iron. Austempered nodular cast iron has improved mechanical properties and a different matrix microstructure compared to known iron-based castings. This type of casting is obtained by isothermal improvement - austempering, whereby the resulting microstructure consists of a mixture of ausferitic (acicular) ferrite and residual, isothermally transformed, carbon-enriched, stable, austenite. Changing the austempering parameters (temperature and time of austenitization and isothermal transformation) affects the obtained ausferite microstructure, and thus the mechanical properties. The most influential parameter that affects the mechanical properties of austempered ductile iron is the isothermal transformation temperature. This paper will present the relationship between microhardness values and microstructural transformations in the material due to the effect of elevated temperatures. [ABSTRACT FROM AUTHOR]

The aim of this work is to determinate the temperature start of precipitation of the secondary phases in austenitic stainless steels with delta ferrite. Presence of the delta ferrite in austenitic stainless steel promotes the precipitation of the secondary phases especially carbides and sigma phase whose have effect on quality of steel. The microstructure was characterized after a solution annealing at 1030 ℃ followed by annealing in temperature range from 550 to 1000 ℃ for the time of 30 minutes and cooling in air. Etched samples were observed using optical microscopy and scanning electron microscopy. The delta ferrite content was determined by a Feritscope MP30. Analysis of microstructure showed that the first phases precipitate between 550 and 650 ℃ at α/γ boundaries and delta ferrite. Sigma phase starts to precipitate between 650 and 750 ℃ at α/γ boundaries. [ABSTRACT FROM AUTHOR]

Steel 42CrMo4 is the chromium, molybdenum and manganese low alloy steels usually used in hardened and tempered state. In this state this steel has good toughness, good torsional and fatigue strength. Its application is for statically and dynamically stressed components for engines and machines. In this article, the results of influence of different form of heat treatment on quality (microstructure and hardness) of steel are presented. Heat treatments like annealing (normalizing and soft annealing), hardening and tempering are carried out in atmospheric condition. From the results could be seen that in opposite of annealing the hardening treatment improves hardness of the material. Tempering process decreases hardness but it still higher than in the case of annealing. Microstructural analysis shows that temperature of heat treatment and a cooling rate had very important influence on microstructure and hardness of steel. [ABSTRACT FROM AUTHOR]

Steel 67SiCr5 is a alloyed carbon steel usually used for production of springs. It is used for load bearing springs, ring-shape springs, spiral springs, anti vibration springs etc. Springs steels are usually distribute in annealed or hardened and tempered state. Heat treating could be performed before or after springs forming. In this article, the results of influence of different form of heat treatment on microstructure and hardness are presented. Heat treatments like annealing (normalizing and soft annealing), hardening and tempering are carried out in atmospheric condition. From the results could be seen that in opposite of annealing the hardening treatment improves hardness of the material. Tempering process decreases hardness but it still higher than in the case of annealing. Microstructural analysis shows that temperature of heat treatment and a cooling rate had very important influence on microstructure. Also, a presence of a decarburization was noticed. [ABSTRACT FROM AUTHOR]

Mechanical properties of the ductile iron strongly depend on its microstructure. Different microstructural constituents result in different values of mechanical and ductile properties of ductile iron castings. One of the possibilities to design (define) microstructure of ductile iron castings is an application of different heat treatment processes. In this paper it is presented the influence of different heat treatment processes on final microstructure and properties of ductile iron samples. [ABSTRACT FROM AUTHOR]

In the technology of bentonite mixture mold unexplored fields are the properties of a mixture of a quartz sand fraction 0.106 mm, 0.3 mm and 0.425 mm and the possibility of stacking in horizontal layers in the mold. The investigation is related to the layers of the following combination of sand fractions: 0.3 / 0.106 / 0.425 mm, 0.106 / 0.425 / 0.3 mm and 0.106 / 0.3 / 0.425 mm. Examples of good praxis in castings, smooth surface castings are bound to the use of a model mixture in the front layer casting mold. The results of the research show a high smoothness of the surface of the oil pump cover made in the mold of bentonite mixture from one fraction 0.3 mm of quartz sand. [ABSTRACT FROM AUTHOR]

Austempered Ductile Iron (ADI) is obtained by exactly controlled heat treatment process of nodular cast iron. Ductile iron samples are first austenitised to dissolve carbon, then quenched rapidly to the austempering temperature to avoid the formation of deleterious pearlite or martensite. Resulting ausferrite microstructure consists of acicular ferrite embedded in stabile retained austenite. A new microstructure results with capability superior to many traditional, high performance, ferrous and aluminum alloys. Influence of heating rate on stability during working life of ADI casting, using thermal analysis (DTA), is presented in this paper. [ABSTRACT FROM AUTHOR]

Copyright of Proceedings on Metallic & Nonmetallic Materials is the property of University of Zenica, Faculty of Metallurgy & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Proceedings on Metallic & Nonmetallic Materials is the property of University of Zenica, Faculty of Metallurgy & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Proceedings on Metallic & Nonmetallic Materials is the property of University of Zenica, Faculty of Metallurgy & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Proceedings on Metallic & Nonmetallic Materials is the property of University of Zenica, Faculty of Metallurgy & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Proceedings on Metallic & Nonmetallic Materials is the property of University of Zenica, Faculty of Metallurgy & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Proceedings on Metallic & Nonmetallic Materials is the property of University of Zenica, Faculty of Metallurgy & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)