scholarly journals A thermodynamic assessment of precipitation, growth, and control of MnS inclusion in U75V heavy rail steel

2021 ◽  
Vol 40 (1) ◽  
pp. 178-192
Author(s):  
Wen-Qiang Ren ◽  
Lu Wang ◽  
Zheng-Liang Xue ◽  
Cheng-Zhi Li ◽  
Hang-Yu Zhu ◽  
...  
Keyword(s):  
Particle Size ◽  
Rail Steel ◽  
Solidification Process ◽  
Segregation Ratio ◽  
Two Phase ◽  
Final Particle ◽  
Solid Liquid ◽  
And Control ◽  
Heavy Rail ◽  
Heavy Rail Steel

Abstract Thermodynamic analysis of the precipitation behavior, growth kinetic, and control mechanism of MnS inclusion in U75V heavy rail steel was conducted in this study. The results showed that solute element S had a much higher segregation ratio than that of Mn, and MnS would only precipitate in the solid–liquid (two-phase) regions at the late stage during the solidification process at the solid fraction of 0.9518. Increasing the cooling rate had no obvious influence on the precipitation time of MnS inclusion; however, its particle size would be decreased greatly. The results also suggested that increasing the concentration of Mn would lead to an earlier precipitation time of MnS, while it had little effect on the final particle size; as to S, it was found that increasing its concentration could not only make the precipitation time earlier but also make the particle size larger. Adding a certain amount of Ti additive could improve the mechanical properties of U75V heavy rail steel due to the formation of TiO x –MnS or MnS–TiS complex inclusions. The precipitation sequences of Ti3O5 → Ti2O3 → TiO2 → TiO → MnS → TiS for Ti treatment were determined based on the thermodynamic calculation.

Effects of Rare Earths on Structural Transformation of Heavy Rail Steel

2011 ◽  
Vol 194-196 ◽  
pp. 237-242
Author(s):  
Cheng Jun Liu ◽  
Ya He Huang ◽  
Mao Fa Jiang
Keyword(s):  
Cooling Rate ◽  
Incubation Period ◽  
Rare Earths ◽  
Rail Steel ◽  
Vacuum Induction Furnace ◽  
Critical Cooling Rate ◽  
The Stability ◽  
Heavy Rail ◽  
Electronic Microscope ◽  
Heavy Rail Steel

Clean heavy rail steel was prepared by the process of vacuum induction furnace smelting, forge work and rolling. Effects of Rare earths (RE) on phase transformation and microstructure of heavy rail steel were investigated by thermal simulation machine, metallographic microscope and scanning electronic microscope. Thermal simulate tests indicate that, RE can move the C curve of pearlite transformation to lower right, prolong the incubation period of pearlite and improve the stability of undercooled austenite. The minimum incubation period of pearlite transformation is increased from 24s to 30s by RE. Furthermore, RE can decrease the critical cooling rate of pearlite transformation from 1°C•s-1to 0.5°C•s-1and the critical cooling rate of quenching from 15°C•s-1to 13°C•s-1. Additionally, RE can fine the annealing and anormalizing pearlite notably. The pearlite laminae distance of heavy rail steel added RE is decreased by 12.9% (annealing) and 13.3% (normalizing), respectively.

scholarly journals Prediction on the spatial distribution of the composition of inclusions in a heavy rail steel continuous casting bloom

2020 ◽  
Vol 9 (3) ◽  
pp. 5648-5665 ◽  
Author(s):  
Qiang Ren ◽  
Yuexin Zhang ◽  
Lifeng Zhang ◽  
Jujin Wang ◽  
Yanping Chu ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Continuous Casting ◽  
Rail Steel ◽  
Steel Continuous Casting ◽  
Heavy Rail ◽  
Heavy Rail Steel

Effects of Cooling on Bending Process of Heavy Rail Steel After Hot Rolling

2016 ◽  
Vol 5 (3) ◽  
pp. 196-206 ◽  
Author(s):  
Lin Chen ◽  
Min Yang ◽  
Yunchao Xu ◽  
Zhiyang Zhang ◽  
Zeyuan Li ◽  
...  
Keyword(s):  
Hot Rolling ◽  
Rail Steel ◽  
Bending Process ◽  
Heavy Rail ◽  
Heavy Rail Steel

Numerical and experimental research on the erosion of solid-liquid two-phase flow in transport butterfly valve based on DEM method

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Benliang Xu ◽  
Zuchao Zhu ◽  
Zhe Lin ◽  
Dongrui Wang ◽  
Guangfei Ma
Keyword(s):  
Particle Size ◽  
Turbulence Model ◽  
High Speed ◽  
Two Phase Flow ◽  
Flow Characteristics ◽  
Phase Flow ◽  
Butterfly Valve ◽  
Two Phase ◽  
Content Type ◽  
Solid Liquid

Purpose The purpose of this paper is to analyze the mechanism of particle erosion in butterfly valve pipelines under hydraulic transportation conditions. The results will affect the sealing and safety of butterfly valve pipelines and hopefully serve as reference for the anti-erosion design of butterfly valve pipelines. Design/methodology/approach Through the discrete element method (DEM) simulation that considers the force between particles, the detached eddy simulation (DES) turbulence model based on realizable k-epsilon is used to simulate the solid-liquid two-phase flow-induced erosion condition when the butterfly valve is fully opened. The simulation is verified by building an experimental system correctness. The solid-liquid two-phase flow characteristics, particle distribution and erosion characteristics of the butterfly valve pipeline under transportation conditions are studied. Findings The addition of particles may enhance the high-speed area behind the valve. It first increases and then decreases with increasing particle size. With increasing particle size, the low-velocity particles change from being uniformly distributed in flow channel to first gathering in the front of the valve and, then, to gathering in lower part of it. Fluid stagnation at the left arc-shaped flange leads to the appearance of two high-speed belts in the channel. With increasing fluid velocity, high-speed belts gradually cover the entire valve surface by focusing on the upper and lower ends, resulting in the overall aggravation of erosion. Originality/value Considering the complexity of solid-liquid two-phase flow, this is the first time that the DEM method with added inter-particle forces and the DES turbulence model based on realizable k-epsilon has been used to study the flow characteristics and erosion mechanism of butterfly valves under fully open transportation conditions.

Numerical Simulation of the Effect of the Size of Nanoparticles on the Solidification Process of Nanoparticle-Enhanced Phase Change Materials

2012 ◽  
Author(s):  
Yousef M. F. El Hasadi ◽  
J. M. Khodadadi
Keyword(s):  
Particle Size ◽  
Phase Change ◽  
Phase Change Materials ◽  
Concentration Field ◽  
Solidification Process ◽  
Liquid Interface ◽  
Constitutional Supercooling ◽  
Fluid Mixture ◽  
Solid Liquid Interface ◽  
Solid Liquid

Nanoparticle-enhanced phase change materials (NEPCM) were proposed recently as alternatives to conventional phase change materials due to their enhanced thermophysical properties. In this study, the effect of the size of the nanoparticles on the morphology of the solid-liquid interface and evolving concentration field, during solidification had been reported. The numerical method that was used is based on the one-fluid-mixture model. The model takes into account the thermal as well as the solutal convection effects. A square cavity model was used in the simulation. The NEPCM that was composed of a suspension of copper nanoparticles in water was solidified from the bottom. The nanoparticles size used were 5 nm and 2 nm. The temperature difference between the hot and cold sides was 5 degrees centigrade and the loading of the nanoparticles that have been used in the simulation was 10% by mass. The results obtained from the model were compared with those existing in the literature, and the comparison was satisfactory. The solid-liquid interface for the case of NEPCM with 5 nm particle size was almost planar throughout the solidification process. However, for the case of the NEPCM with particle size of 2 nm, the solid-liquid interface evolved from a planar stable shape to an unstable dendritic shape, as the solidification process proceeded with time. This was attributed to the constitutional supercooling effect. It has been observed that the constitutional supercooling effect is more pronounced as the particle size decreases. Furthermore, the freezing time increases as the particle size decreases.

Numeration Simulation of Solid-Liquid Two-Phase Flow in Centrifugal Sewerage Pump

2010 ◽  
Vol 44-47 ◽  
pp. 345-348 ◽  
Author(s):  
Jian Hua Liu ◽  
Ming Yi Zhu
Keyword(s):  
Particle Size ◽  
Solid Particle ◽  
Working Condition ◽  
Two Phase Flow ◽  
Volume Fraction ◽  
Phase Flow ◽  
Operation Condition ◽  
Two Phase ◽  
And Performance ◽  
Solid Liquid

By Means of Fluent 6.3，the paper simulated the solid-liquid two-phase flow to a centrifugal sewerage pump，using Eulerian Mixture Model under different working condition and different particle size. The simulation draws some conclusion on distributive rules of solid particle inside impeller passage. The results for this simulation were as following: Distributive rules of solid particle inside impeller passage mainly relate to particle size. Meanwhile，the volume fraction of particles and operation condition have influence on distributive rules of solid particle. The simulated results can explain commendably that attrition took place inside pump passage when pump transported solid-liquid two-phase flow. Meanwhile，the simulated results have reference price to improve the design for pump and performance of pump.

Effects and Mechanisms of Niobium on the Fracture Toughness of Heavy Rail Steel

2010 ◽  
Vol 163-167 ◽  
pp. 110-116 ◽  
Author(s):  
Cheng Jun Liu ◽  
Ya He Huang ◽  
Hong Liang Liu ◽  
Mao Fa Jiang
Keyword(s):  
Fracture Toughness ◽  
Grain Size ◽  
Crack Growth ◽  
Rail Steel ◽  
Vacuum Induction Furnace ◽  
Austenite Grain Size ◽  
Niobium Content ◽  
Austenite Grain ◽  
Heavy Rail ◽  
Heavy Rail Steel

Heavy rail steel was prepared by the process of vacuum induction furnace smelting, forge work and rolling. Effects and mechanisms of niobium on the fracture toughness of heavy rail steel were investigated. In addition, the appropriate range of niobium content for heavy rail steel was determined. With the niobium content increasing, both the austenite grain size and pearlite laminae distance of heavy rail steel were decreased gradually at first and then increased rapidly. When the niobium content was low, the precipitates containing niobium predominantly appeared in the cementite, which improved the toughness of heavy rail steel by fining the austenite grain size and pearlite laminae distance; when the niobium content > 0.024%, the fine dispersed precipitates containing niobium mainly occurred in the ferrite, which improved the toughness of heavy rail steel by pining dislocations and inhibiting crack growth; with the niobium content increasing, both the quantity and size of precipitates containing niobium were increased gradually; when the niobium content > 0.073%, most precipitates containing niobium could not pin dislocations and inhibit crack growth because the particles size was too big, thus the fracture toughness of heavy rail steel was bad. So the optimum range of the niobium content could improve the fracture toughness of heavy rail steel. In the present study, when the niobium content was about 0.053%, the fracture toughness of heavy rail steel was the best. The maximum plane-strain fracture toughness was 49.88 MPam1/2.

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