Pearlite

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

Effects of titanium addition and section size on microstructure and mechanical properties of compacted graphite cast iron

Abstract: Titanium is an anti-spheroidizing element and also carbide former in ductile iron. On the other hand, increasing the casting size essentially lowers the cooling rate that opposes the chilling tendency of titanium. This research was to study the combined effects of titanium and section size on their promotion of compacted graphite (CG) formation, and at the same time how matrix constituents were altered in heavy-wall castings. It was found that at the increasing casting thickness of 30 mm, 65 mm and 80 mm, the percentage of CG increased while that of pearlite decreased either with or without titanium addition. However, titanium (added in an amount of 0.15 wt%) effectively promoted the formation of CG by over 10% and at the same time increased the pearlite content in the matrix. This was especially true in the thinner 30 mm casting. Irons with titanium addition exhibited a bit lower Brinell hardness, elongation, and impact toughness due probably to the higher CG percentage that facilitated easier crack propagation. However, comparing to the un-alloyed iron, fracture toughness increased along with tensile strength for iron with titanium addition in all casting sizes of 30–80mm. The higher pearlite content in the matrix has overridden the effect of increased CG percentage such that tensile strength and KIC value both increased.

Influence of Microstructure on Strength and Ductility in Fully Pearlitic Steels

Abstract: This article deals with the relationship between the microstructure and both strength and ductility in eutectoid pearlitic steel. It is seen how standard mechanical properties and fracture micromechanisms are affected by heat treatment and the resulting microstructure in the material. The yield stress, the ultimate tensile strength and the ductility (measured by means of the reduction in area) exhibit a rising trend with the increasing cooling rate (associated with smaller pearlite interlamellar spacing and a lower pearlitic colony size), while the strain for maximum load shows a decreasing tendency with the afore-said rising cooling rate. With regard to the fracture surface, its appearance becomes more brittle for lower cooling rates, so that the fracture process zone exhibits a larger area with observable pearlite lamellae and a lower percentage of microvoids.

Dilatometric analysis on phase transformations of intercritical annealing of Fe−Mn−Si and Fe−Mn−Si−Cu low carbon TRIP steels

Abstract: Evaluations of austenite fraction and transformation kinetics upon intercritical annealing of low carbon TRIP steels were attempted using quantitative dilatometric analysis The measured dilation curves were analyzed by taking the carbon distribution between austenite and its decomposed phases into account The amount of austenite formed during intercritical annealing and its carbon content obtained by dilatometric measurement was compared with the values predicted by thermodynamic calculations under the ortho-equilibrium and para-equilibrium conditions The kinetics of the reaustenization process including pearlite dissolution and non-isothermal and isothermal formation of austenite could be quantitatively characterized by means of a modified JMAK (Johnson-Mehl-Avrami-Kolmogrov) equation

Strengthening in pearlite formed from thermomechanically processed austenite in vanadium steels and implications for toughness

Abstract: Strengthening in the pearlite of 0·75C–1·2Mn (wt-%) steels resulting from microalloying with 0·09–0·16% V was examined. The steels were transformed by controlled cooling in a dilatometer at...

Effects and Mechanisms of RE on Impact Toughness and Fracture Toughness of Clean Heavy Rail Steel

Abstract: Clean high carbon heavy rail steel was prepared by the process of vacuum induction furnace smelting, forging and rolling. Mechanisms of RE on the impact toughness and fracture toughness for clean high carbon steel were investigated. In addition, the appropriate range of RE content for clean high carbon steel was determined. Both the austenite grain size and pearlite lamellar spacing decreased due to small amount of RE, consequently the impact toughness and fracture toughness were improved evidently. When the RE content exceeded a critical value, the pearlite lamellar spacing was increased, because RE was segregated on the austenite grain boundaries, damaged the orientation relationship of pearlite transformation, caused the disorder growth and morphology degenerating of pearlite. With the increasing of RE content, both the impact toughness and fracture toughness of clean high carbon steel were gradually increased at first and then decreased. It was found that when the RE content was between 0. 008 1% and 0.008 8 %, both the impact toughness and fracture toughness of clean high carbon heavy rail steel were the best. The maximum ballistic work was 21.2 J (20 °O and 12. 2 J ( — 20 °O, respectively. The maximum plane-strain fracture toughness was 45.67 MPa • m1/2 (20 °O and 37. 04 MPa • m1/2 (-20 °O, respectively.