Topic
Pearlite
About: Pearlite is a research topic. Over the lifetime, 6028 publications have been published within this topic receiving 65695 citations.
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TL;DR: In this article, surface roughness, workpiece microstructure and burr size for micro-machined parts as well as tool wear were examined over a range of feed rates.
Abstract: In the mechanical micro-machining of multiphase materials, the cutting process is undertaken at a length scale where material heterogeneity has to be considered. This has led to increasing interest in optimising the process parameters for micro-machining of such materials. In this study the micro-machinability of two steels, a predominantly ferrite material (AISI 1005) and a near-balanced ferrite/pearlite microstructure (AISI 1045) was studied. Workpiece sample deformation properties were characterised by nano-indentation testing. Additionally, metallographic grain size evaluation was undertaken for the workpiece microstructures. Surface roughness, workpiece microstructure and burr size for micro-machined parts as well as tool wear were examined over a range of feed rates. The results suggest that for micro-machined parts, differential elastic recovery between phases leads to higher surface roughness when the surface quality of micro-machined multiphase phase material is compared to that of single phase material. On the other hand, for single phase predominantly ferritic materials, reducing burr size and tool wear are major challenges. Thus, the paper elucidates on material property effects on surface and workpiece edge quality during micro-milling.
50 citations
TL;DR: In this article, the authors examined the structures produced in a Nb-microalloyed steel by oil quenching after intercritical anneals at 760 and 810 °C.
Abstract: The structures produced in a Nb-microalloyed steel by oil quenching after intercritical anneals at 760 and 810 °C have been examined by light and transmission electron microscopy. After both anneals, the periphery of the austenite pool transforms on cooling to ferrite in the same orientation as the ferrite retained during intercritical annealing. Thus the ferrite forms by an epitaxial growth mechanism without the formation of a new interface or grain boundary. The new ferrite is precipitate-free in contrast to the retained ferrite which develops a very dense precipitate dispersion during intercritical annealing. In the carbonenriched interior of the austenite pool beyond the epitaxial ferrite only martensite forms in specimens annealed at 760 °C but various mixtures of ferrite and cementite form in specimens annealed at 810 °C. The latter structures include lamellar pearlite, a degenerate pearlite, and cementite interphase precipitation. All Nb is in solution in the austenite formed at 810 °C, and therefore the low hardenability of the specimens annealed at that temperature is best explained by the effect of low austenite carbon content.
50 citations
TL;DR: In this article, friction stir welding (FSW) was used to weld dissimilar metals (SS304 and Q235 low carbon steel) and the microstructure, interfacial characteristics, residual stress distribution and mechanical properties of the joint were investigated.
50 citations
TL;DR: In this article, the quenching hardness can be satisfactorily described as a function of the C+N content if, taking into account the Nb, Zr, Ta, Hf fractions, a common effectiveness factor is calculated.
Abstract: Comprehensive development work on martensitic steels belonging to the so-called 12% Cr steel group were performed at the Institute for Materials Research (IMF) of Forschungszentrum Karlsruhe on martensitic steels, the so-called 12% Cr steel group, in order to meet the various requirements in nuclear and conventional energy technology. The transformation characteristics of 29 different grades of steel and 38 heats have been determined and continuous cooling transformation (CCT) diagrams have been prepared. The diagrams are first described by groups of subjects in a chronological order because the change in the chemical composition cannot be correlated in all cases with the change in transformation behaviour. The quenching hardness can be satisfactorily described as a function of the C+N content if, taking into account the Nb, Zr, Ta, Hf fractions, a common effectiveness factor is calculated. This effectiveness factor is also integrated in the calculation of the Ms point by modifying accordingly the equation proposed by Steven and Haynes for low-alloy steels and supplemented by the summands for V and W. An equation is introduced for the calculation of the critical cooling rate for pearlite transformation which takes into account the special influence exerted by elements Cr, V, Mo, W, Ge. The comparison between calculated and measured values for Ms and Vcrit is satisfactory, except for some steels.
50 citations
Patent•
31 Aug 1943
TL;DR: This invention relates to a method and means of expanding pearlite (sometimes spelled perlite), mica, and like expandible or exfoliating materials as mentioned in this paper, which is a brittle, friable mineral, black to pearl gray in color.
Abstract: This invention relates to a method and means of expanding pearlite (sometimes spelled perlite), mica, and like expandible or exfoliating materials. Pearlite is a brittle, friable mineral, black to pearl gray in color, the name being applied to it to distinguish it from obsidian, another form...
50 citations