The effect of austenitizing conditions in the ductile iron hardening process on longitudinal ultrasonic wave velocity

The paper presents results of a research on the effect of austenitizing temperature and time adopted in the hardening operation on the ultrasonic wave velocity in ductile iron. It has been found that with increasing austenitizing temperature and with the passage of the austenitizing time, a monotonic decrease of the ultrasonic longitudinal wave velocity value occurred. Implementation of ultrasonic testing of results obtained in the course of the cast iron hardening process both in production and as-cast conditions, requires development of a test methodology that must take into account the influence of base material structure (degree of nodularization, graphite precipitation count) on the ultrasound wave velocity

Service life of a pressure mould with heat-barrier and anti-erosion coating

The present paper deals with the issue of determination of the cause of wear of a thermally processed and nitrided pressure mould with (Ti, Al)(C, N) coating. It was found that the service life of the (Ti, Al)(C, N) coating was affected neither by the substrate surface irregularities nor presence of non-metallic inclusions. It can be supposed that the use of a thicker coat can be favourable in view of mitigation of the effect of sudden mould temperature changes in the course of pouring and mould surface cooling down

The effect of austenitizing conditions in the ductile iron hardening process on longitudinal ultrasonic wave velocity

The paper presents results of a research on the effect of austenitizing temperature and time adopted in the hardening operation on the ultrasonic wave velocity in ductile iron. It has been found that with increasing austenitizing temperature and with the passage of the austenitizing time, a monotonic decrease of the ultrasonic longitudinal wave velocity value occurred. Implementation of ultrasonic testing of results obtained in the course of the cast iron hardening process both in production and as-cast conditions, requires development of a test methodology that must take into account the influence of base material structure (degree of nodularization, graphite precipitation count) on the ultrasound wave velocity

Influence of the microstructure of cast iron on the rheological properties of frictional contact and wear-resistance a*

Abstract The influence of sliding speed and contact load on wear-resistance of cast iron in the unhardened state (cast without heat treatment) and in the state after surface hardening by electroarc plasma (GTAW method) is investigated. This method provides formation of composite hardening structure in the process of fast crystallization. It is shown, that during friction of hardened cast iron the contribution of mechanical-thermal hardening with simultaneous development of relaxation processes prevails over mechanical peening. It provides high level and stability of wear-resistanc

Combustion Engine Cylinder Liners Made of Al-Si Alloys

Abstract The paper deals with problems related to application of aluminum-silicon alloys for combustion engine cylinder liners

Abrasive wear resistance of a quenched and sub-zero treated high-chromium white cast iron

The study reported in this paper concerned development of such microstructure of high-chromium (24 % Cr) cast iron which could secure high abrasive wear resistance of die inserts used to fabricate stampings from refractory materials. It was found that by increasing the cast iron cooling rate as a result of thermal interaction with the chill, it is possible to obtain fine carbide precipitates with diversified morphology, rich in Cr and Fe, containing Mo and Si. The matrix in the regions of thermal interaction with the chill was enriched in Cr and Mo, but depleted of Fe and Si. The sub-zero treatment process was developed to secure presence of hardening products in the matrix. The obtained structure of high-chromium cast iron has made the inserts more resistant to abrasive wear compared to tool steels after hear treatment used earlier

Application of ceramic coating to improve abrasive wear resistance of die inserts used to press-mould stampings of refractories

The paper presents results of a study on abrasive wear resistance of die inserts for composite moulds used to pressmould stampings from refractory materials, determined based on susceptibility to scratching with a diamond indenter. For the study, two inserts of high-chromium cast iron were prepared, of which one was provided with a ceramic coating (60 % Al2O3 + 40 % TiO2) with a metallic interlayer (NiAlCrSi). Both layers were deposited by means of the Atmospheric Plasma Spraying (APS) method. The obtained scratch test results indicate that with the use of the same load force (20 N), die inserts with ceramic coating are characterized with less indenter penetration depth which should translate to higher resistance to abrasive wear

Geometry of remeltings and efficiency of the surface remelting process applied to cobalt alloy castings

The paper summarises results of measurements of remelting area geometry, thermal efficiency and melting efficiency characterising the surface remelting process applied to castings of MAR-M-509 cobalt alloy. The remelting process was carried out with the use of GTAW (Gas Tungsten Arc Welding) method in protective atmosphere of helium, at the electric current intensity in the range from 100 A to 300 A, and the electric arc scanning velocity vs in the range from 200 mm/min to 800 mm/min. The effect of current intensity and electric arc scanning velocity on geometrical parameters of remeltings, thermal efficiency, and melting efficiency characterising the remelting process has been determined