Cutting performance of deep cryogenic treated and nitrided HSS cutting tool inserts

High speed steel (HSS) is a very important industrial tool material and has been constantly improved for different wear resistance applications and cutting tools, i.e. drills, milling cutters, hobs and for the cutting tools in which the economical cutting speed is too low for choosing the carbide tools. The properties of HSS depend significantly on the parameters of the conducted heat treatment. In this paper, the influence of deep cryogenic treatment in combination with nitriding of metallurgical powder metallurgy HSS on the wear resistance was measured. Additionally, the cutting performance in a single point cutting tool machinability test at the configuration of the dry low-speed turning of steel was investigated. The results showed that deep cryogenic treatment itself, and in combination with nitriding, resulted in the reduction of the wear rate. The results of the single point cutting tool machinability test showed that deep cryogenic treated and nitrided HSS inserts performed worse than the classically heat-treated inserts and deep cryogenic treated HSS inserts exhibited approximately the same flank wear as the nitrided ones

Shear Bond Strength in Zirconia Veneered Ceramics Using Two Different Surface Treatments Prior Veneering

Aim of the study was to assess the effect of different surface treatments on the shear bond strength (SBS) of the veneering ceramics to zirconia core. In a shear test the influence of grinding and sandblasting of the zirconia surface on bonding were assessed. Statistical analysis was performed using SPSS statistical package (version 17.0, SPSS Inc., Chicago, IL, USA) and Microsoft Office Excel 2003 (Microsoft, Seattle, WA, USA). There was a significant difference between the groups considering shear bond strength (SBS) values, i.e. ground and sandblasted samples had significantly higher SBS values than only ground samples (mean difference=–190.67; df=10, t=–6.386, p<0.001). The results of the present study indicate that ground and sandblasted cores are superior to ground cores, allowing significantly higher surface roughness and significantly higher shear bond strength between the core and the veneering material

Zbornik sažetaka Međunarodnog savjetovanja MATRIB 2010

Zbornik sažetaka Međunarodnog savjetovanja MATRIB 2010 održanog u Veloj Luci od 23. do 25.06.2010

Zbornik radova međunarodnog savjetovanja MATRIB 2010

Zbornik radova s međunarodnom recenzijom objavljen u sklopu međunarodnog savjetovanja MATRIB koje se bavi materijalima i tribologijom, održanog od 23.-25.06.2010. u Veloj Luci, Hrvatska

Characterization of Foxing Stains on Eighteenth Century Books

Foxing is a form of chromatic alteration of paper which appears as spotty or diffuse yellowish, brownish, reddish or blackish areas. Although the nature of foxing stains is not fully understood, microorganisms and metallic impurities (iron, copper, etc.) in paper have been considered the main causes of foxing formation. This paper deals with the application of scanning electron microscopy (SEM) and elemental analysis for the presence of metals and/or microorganisms in foxing spots, found in eighteenth century books. The selected spots are also examined in normal and UV light to determine the relationship between the visual appearance of the paper and its chemical composition. The conservation methods suitable for the removing of foxing stains and prevention of their recurrence are discussed

Microstructural changes in heat treatment of PM high-speed steels

Properly performed heat treatment can significantly affect final properties of high-speed steels, so the heat treatment parameters are chosen depending on the specific properties of the particular tool. Deep cryogenic treatment is carried out at a temperature of -196 °C (liquid nitrogen). By combining deep cryogenic treatments and various austenitization temperatures, which affects the volume of retained austenite, it is possible to affect the hardness and fracture toughness of tools and other steel parts. However, it may also affect the increase in wear resistance regardless of the increase in hardness. In addition, dimensional stability is achieved by transformation of residual austenite into martensite, eliminating the change in volume by 4%. This paper investigated the effect of deep cryogenic treatment on microstructures in high-speed steel produced by powder metallurgy in comparison to vacuum heat treatment

Wear of Induction Cladded Coating in the Abrasive Mass at Various Speeds and Impact Angles

The wear of induction cladded coating during motion was investigated through the abrasive mass at a speed of 1.0 to 3.0 m/s and the impact angle of abrasive particles with a worn surface of 0° to 90°. Cladding was performed by using Ni-Cr-Si-B-Fe flame spraying powder. Experimental research was carried out by using the Response Surface Method (RSM) and Central Composite Design (CCD). Analysis of variance proved that both motion speed and impact angle had significant impact on the wear of coating, both individually and interactively. Motion speed had the greatest influence, and the interaction of speed and angle had the least influence. The wear rate increased along with the motion speed increase, and the influence of the impact angle depends on the wear speed. At a speed of 1 m/s, the wear increases along with the increase of angle from 0° to 45° and then continues to decrease up to the angle of 90°. At a speed of 2 m/s, the wear increases along with the angle increase from 0° to 30° and then continues to decrease up to the angle of 90°. At a speed of 3 m/s, the wear increases along with the angle increase from 0° to 20° and then decreases as the angle increases up to 90°. Based on the statistical data processing, this research developed the mathematical model of wear in the form of quadratic polynomial that describes the influences of input variables in individual and interactive form