Wyniki wyszukiwania - BazTech

1

Bainitic reaction and microstructure evolution in two normalized and tempered steels designed for service at elevated temperatures

Ławrynowicz Z.

Advances in Materials Science

|

2017

|

Vol. 17, nr 4(54)

22--36

EN

In the present work conventional heat treatment like normalizing (bainitic microstructure) and tempering of the alloys has been performed. The materials used in this study were two steels, one the laboratory prepared experimental low alloy Cr-Mo steel in comparison to typical commercial 10CrMo9-10 steel. The determined carbon concentrations of the residual austenite at the different temperatures of bainite transformation supports the hypothesis that the growth of bainitic ferrite occurs without any diffusion with carbon being partitioned subsequently into the residual austenite. It was found that bainitic reaction has stopped when average carbon concentration of the untransformed austenite is close to the T0 line and supports formation of bainitic ferrite by a shear mechanism, since diffusionless transformation is not possible beyond the T0 curve. Normalized samples were air cooled down to room temperature before tempering at various temperatures in the range of 500-750°C. Samples have been austenitized at 980°C for 0.5 hour air cooled and tempered at 500, 550, 600, 650, 700 and 750°C for 1 hour. After heat treatment, the assessment in the microstructure and phase precipitation was made using the samples prepared for metallographic and transmission electron microscope (TEM) on thin foils analysis. Quantitative X-ray analysis was used to determine the retained austenite content after heat treatment like normalizing and tempering and the total volume fraction of the retained austenite was measured from the integral intensity of the (111)γ and (011)α peaks. The changes observed in the microstructure of the steel tempered at the higher temperature, i.e. 750°C were more advanced than those observed at the temperature of 500°C. Performed microstructural investigations have shown that the degradation of the microstructure of the examined steel was mostly connected with the processes of recovery and polygonization of the matrix, disappearance of lath bainitic microstructure, the growth of the size of M23C6 carbides, and precipitation of the secondary M2C precipitates. The magnitude of these changes depended on the temperature of tempering.

2

The effect of the heat treatment on the 7CrMoVTiB10-10 steel's microstructure and its properties

Bolanowski P.

Challenges of Modern Technology

|

2015

|

Vol. 6, no. 2

10--14

EN

According to the European Standard PN-EN 10216-2 two types of the heat treatment could apply to 7CrMoVTiB10-10 – the modern bainitic boiler steel. The 7CrMoVTiB10-10 steel may have different properties, depending on the chosen method of the heat treatment. This paper shows the differences in the microstructure and the properties occuring after two processes: one of them including normalization and tempering, and the other – hardening and tempering.

3

O jakościowo lepszym drucie liniarskim i korzyściach dla wytwórcy

Golis B., Pilarczyk J.W., Budzik R., Kruszyński S.

Hutnik, Wiadomości Hutnicze

|

2006

|

Vol. 73, nr 7

361-364

PL

W artykule przedstawiono zagadnienie związane z wyborem rodzaju obróbki cieplnej drutów: patentowanie, normalizowanie dla uzyskania wysokich własności drutów na liny i obniżenia kosztów wytwarzania.

EN

The paper describes some aspects concerned with selection of wire heat treatment. The processes of patenting and normalizing were tested for obtaining higher quality of the rope wires and cutting production costs.