Pearlite

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

High tensile galvannealed steel sheet having excellent workability and molten metal embrittlement crack reistance

Abstract: PROBLEM TO BE SOLVED: To provide a high tensile galvannealed steel sheet which exhibits a high tensile force of ≥580 Mpa, is improved in molten metal embrittlement resistance during spot welding, and is excellent in weldability and workability. SOLUTION: The composition of the base steel (each by mass%) of the steel sheet comprises 0.04 to 0.25% C, 0.01 to 2.0% Si, 0.5 to 3.0% Mn, ≤0.1% P, ≤0.03% S, further one or two or more kinds of 0.001 to 0.1% Ti, 0.001 to 0.1% Nb, 0.01 to 0.3% V, 0.01 to 0.5% Mo, 0.01 to 0.5% Zr, comprises, as necessary, 0.0001 to 0.01% B, wherein the metal structure comprises one or two or more kinds of a ferrite phase, bainite phase, pearlite phase and martensite phase of 40 to 95% in area rate, and the balance 1 to 10% volume fraction residual austenite phase. The metal structure is preferably dispersed with the deposited material or compound deposited material of Ti, Nb, V, Mo, and Zr of 3 to 200 nm in average grain size. COPYRIGHT: (C)2007,JPO&INPIT

Improvement of strength, toughness and ductility in ultrafine-grained low-carbon steel processed by warm bi-axial rolling

Abstract: A 0.15%C-0.3%Si-1.5%Mn steel bar with ultrafine elongated grain structures of transverse grain size 1.2 μm was fabricated via multi-pass bi-axial rolling process at a warm working temperature. For comparison, conventionally quenched and tempered 0.29%C steel and 1.03%C steel with a martensitic structure and 0.15% low-carbon steel with a ferrite/pearlite structure were also prepared. The full-size Charpy V-notch impact and tensile tests were conducted at a temperature range of −196 °C to 200 °C, and the relationship between microstructures, yield stress, reduction in area and impact energy was studied. In the developed steel bar, the main orientation in the microstructure changed in the cross-sectional plane, and it was dominated by {001} cube orientation at the center, {111} at the quarter and rolling direction// at the surface. Crack branching started to occur with decreasing temperature in the Charpy test. The fracture surfaces are very complicated at temperatures below −100 °C and the specimen did not separate into two pieces even at a low temperature of −196 °C. The strength–toughness balance of the developed steel was significantly improved compared with conventional steels. This advantage in the developed steel was also seen in the strength–reduction in area balance. As a result, the steel fabricated by warm bi-axial rolling was best balance in correlation between strength and ductility and between strength and toughness at all temperatures.

High strength bolt having excellent hydrogen embrittlement resistance

Abstract: The present invention provides a high strength bolt that has excellent hydrogen embrittlement resistance. The high strength bolt having excellent hydrogen embrittlement resistance which bolt comprises 0.20 to 0.60% of C, 1.0 to 3.0% of Si, 1.0 to 3.5% of Mn, higher than 0% and not higher than 1.5% of Al, 0.15% or less P, 0.02% or less S, and balance of iron and inevitable impurities, and the structure includes: 1% or more residual austenite; 80% or more in total content of bainitic ferrite and martensite; and 10% or less (may be 0%) in total content of ferrite and pearlite in the proportion of area to the entire structure, and also the mean axis ratio (major axis/minor axis) of the residual austenite grains is 5 or higher and the bolt has tensile strength of 1180 MPa or higher.

On the Yield and Flow Stress of Lamellar Pearlite

Abstract: The experimental (macroscopic) values for the yield and flow stress of fully pearlitic eutectoid carbon steel may be represented by a linear function of either, the inverse of the true interlamellar spacing or its square root. The latter representation determines, however, a negative zero-intercept ordinate in the case of the yield stress. Different theoretical models may be contemplated for the critical resolved shear stress (CRSS) of pearlitic ferrite. Most of them give way to inverse proportionality relationships between the CRSS and either, the apparent interlamellar spacing on the slip plane considered or its square root. A quantitative comparison between the results of non pile-up models and the experimental values of the yield stress is made in this paper, making use of the value of an orientation factor appropiate to pearlitic ferrite obtained previously (Gil Sevillano, Van Houtte and Aernoudt, 1978). Experimental values for the flow stress of pearlite after large strains are also interpreted in this way. The paper stresses the plausibility of non pile-up models against the more widely accepted pile-up models for the yield and flow stress of pearlite.