Pearlite

About: Pearlite is a research topic. Over the lifetime, 6028 publications have been published within this topic receiving 65695 citations.

Continuous cooling transformation diagrams and properties of micro-alloyed TRIP steels

Abstract: Continuous cooling transformation (CCT) diagrams and properties of four kinds of low-silicon C–Mn–Si–Al transformation-induced plasticity (TRIP) steels with different carbon contents, with or without microalloy element Ti/V, as well as a reference TRIP steel containing 1.19 wt.% Si were studied. The CCT diagrams exhibited that as the carbon equivalent (CE) increased, it caused a shift of the ferrite forming and pearlite forming temperatures to the right side and the bainite forming and martensite forming to the lower temperatures of the diagram. The microstructural evolution obtained from the dilatometry samples revealed that the highest cooling rates produced fully martensitic microstructure in all cases except the reference TRIP steel. As the cooling rate decreased, more ferrite and bainite were formed. The increase of CE caused the increase of the amount of martesite in the microstructure. Tensile test and Erichsen test of the investigated steels showed an excellent mechanical strength and ductility combination, with tensile strength between 800 and 1000 MPa, total elongation of around 20%, and a quite good formability with a dome height of about 10 mm in all cases.

Damaging micromechanisms in ferritic–pearlitic ductile cast irons

Abstract: Microstructure influences on damaging mechanisms in ferritic–pearlitic ductile cast irons (DCIs) were investigated. Four different ferrite/pearlite volume fractions were considered, and in situ scanning electron microscope observations were performed during step by step tensile tests in a microtensile holder. SEM observations allowed to identify an evident microstructure influence on ferritic–pearlitic DCIs damaging mechanisms and the key role played by graphite constituents. Phase volume fractions and distribution affect both crack initiation and crack propagation. The importance of the damage mechanism based on graphite nodules–matrix interface cracking, usually indicated as the most relevant, is only partially confirmed, depending on the DCI microstructure.

Microstructure based modeling for the mechanical behavior of ferrite–pearlite steels suitable to capture isotropic and kinematic hardening

Abstract: This study proposes a new microstructure based model for the mechanical behavior of non-microalloyed ferrite–pearlite steels. Its main originality consists in estimating the internal stresses evolving with strain. It takes into account two contributions corresponding to two different scales of the microstructure: the huge internal stresses generated in pearlite all along the deformation and the mesoscopic strain incompatibility between ferrite and pearlite. This estimation allows the distinction to be made between the isotropic and kinematical components of work-hardening. The parameters of the model have been adjusted on numerous results from the literature concerning fully ferritic or pearlitic steels. The performance of the model is then demonstrated on datasets from the literature concerning steels with different fractions of pearlite. The predictions of the model are excellent concerning both tensile behavior and Bauschinger effects. The size effects of lamellar pearlite have been reviewed in this paper, i.e., the impact of interlamellar spacing on mechanical properties. In pearlite, the yield strength scales with s −1 , the internal stress with s −1/2 and the macroscopic strain-hardening (i.e., slope of the tensile curve) do not depend on interlamellar spacing. This review gives new perspectives for the understanding of the mechanical behavior of lamellar structures, such as pearlite or bainite.