scholarly journals Effect of Electric Current Pulse on Microstructure and Corrosion Resistance of Hypereutectic High Chromium Cast Iron

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2220 ◽  
Author(s):  
Haiyang Lv ◽  
Rongfeng Zhou ◽  
Lu Li ◽  
Haitao Ni ◽  
Jiang Zhu ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Cast Iron ◽  
Electric Current ◽  
Current Pulse ◽  
Electric Current Pulse ◽  
High Chromium ◽  
High Chromium Cast Iron ◽  
Microcrack Propagation ◽  
Primary Carbides ◽  
Chromium Cast Iron

The effect of electric current pulse on the microstructure and corrosion resistance of hypereutectic high chromium cast iron was explored. The morphology of carbides in solidification microstructure was observed by an optical microscope and a scanning electron microscope and the composition was determined by an electron probe micro-analyzer. The microhardness of primary carbides and corrosion resistance of samples were also compared. Under the active of electric current pulse, the microstructure of hypereutectic high chromium cast iron was homogenized and its performance improved accordingly. On treatment by electric current, the morphology of primary carbides changed from thick long rods to hexagonal blocks or granular structures. The interlayer spacing of eutectic carbide decreased from ~26.3 μm to ~17.8 μm. Size statistics showed that the average diameter of primary carbide decreased from ~220 μm to ~60 μm. As a result, microhardness increased from 1412 HV to 1511 HV. No obvious microcrack propagation was found at the microindentation sites. The average length of microcracks decreased from ~20.7 μm to ~5.7 μm. Furthermore, corrosion resistance was remarkably enhanced. The average corrosion rate decreased from 2.65 mg/cm2·h to 1.74 mg/cm2·h after pulse current treatment.

scholarly journals Change in Primary (Cr, Fe)7C3 Carbides Induced by Electric Current Pulse Modification of Hypereutectic High Chromium Cast Iron Melt

Materials ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 32 ◽  
Author(s):  
Baoyu Geng ◽  
Rongfeng Zhou ◽  
Lu Li ◽  
Haiyang Lv ◽  
Yongkun Li ◽  
...  
Keyword(s):  
Cast Iron ◽  
Electric Current ◽  
Current Pulse ◽  
Defect Density ◽  
Micro Hardness ◽  
Electric Current Pulse ◽  
High Chromium ◽  
High Chromium Cast Iron ◽  
Primary Carbides ◽  
Chromium Cast Iron

In this work, an electric current pulse (ECP) of 500A was applied on a hypereutectic high chromium cast iron (HHCCI) melt before it began to solidify, and the effect of ECP on primary carbides was investigated. The characteristics of the primary carbides were analyzed by X-ray diffraction (XRD), electron probe micro-analyzer (EPMA), transmission electron microscopy (TEM), micro hardness tester, and other techniques. The results showed that ECP not only refined the primary (Cr, Fe)7C3 carbides, but also decreased the average content of Cr in the primary carbides. At the same time, the average value of micro hardness of the primary carbides increased by about 84 Kgf/mm2, which contradicts existing knowledge that hardness increases with an increase in Cr content. XRD analysis showed that the crystal structure of the primary carbides did not change. The results of EPMA indicated that the Cr/Fe ratio gradually decreased from the center to the edges of the carbide particles. Further investigation revealed that the uneven distribution of elements caused by ECP led to an increase in defects (including twins, antiphase boundaries, and dislocations). This increase in defect density is the main reason for the increase in micro hardness instead of the expected decrease. The mechanism of the change in primary carbides was analyzed in detail in this paper, which has provided a new method for the refinement of primary carbides and for improving the properties of primary carbides.

Effect of Electric Current Pulse on Carbide in Hypereutectic High Chromium Cast Iron

2012 ◽  
Vol 457-458 ◽  
pp. 174-180 ◽  
Author(s):  
Hua Chen ◽  
Rong Feng Zhou ◽  
Ye Hua Jiang ◽  
Rong Zhou
Keyword(s):  
Cast Iron ◽  
Electric Current ◽  
Current Pulse ◽  
Processing Time ◽  
Hard Phase ◽  
Electric Current Pulse ◽  
High Chromium ◽  
High Chromium Cast Iron ◽  
Primary Carbides ◽  
Chromium Cast Iron

It has significant engineering practicability that refining the carbides as hard phase in hypereutectic high chromium cast iron. The high chromium cast iron samples during the course of solidification were treated with electric current pulse (ECP) from the temperature of 1350 °C and 1360 °C. The effects of ECP treatment of starting temperature, processing time on the shape, size, and distribution of primary carbides was investigated. The mechanism of primary carbides refined by ECP process was also analyzed preliminarily.

Microstructure Refinement of Hypereutectic High Chromium Cast Iron with Electric Current Pulse

2013 ◽  
Vol 690-693 ◽  
pp. 147-152 ◽  
Author(s):  
Hua Chen ◽  
Ling Zhang ◽  
Sheng Ming Wang
Keyword(s):  
Cast Iron ◽  
Electric Current ◽  
Current Pulse ◽  
Pulse Frequency ◽  
Solidification Structure ◽  
Electric Current Pulse ◽  
Electric Voltage ◽  
High Chromium ◽  
High Chromium Cast Iron ◽  
Chromium Cast Iron

The effect of electric current pulse (ECP) on the solidification structure of hypereutectic high chromium cast iron was studied. The orthogonal array L9 was used to determine the effect of three process parameters of ECP, which were electric voltage, pulse frequency, pulse width. According to the experimental results, the solidification structure of hypereutectic high chromium cast iron was modified from large grains to finer grains with equiaxed crystals, by allowing the ECP to act on liquid.

Experimental Analysis of Resistance to Electrocorosion of a High Chromium Cast Iron with Applications in the Vehicle Industry

2017 ◽  
Vol 68 (10) ◽  
pp. 2397-2401 ◽  
Author(s):  
Costel Dorel Florea ◽  
Ioan Carcea ◽  
Ramona Cimpoesu ◽  
Stefan Lucian Toma ◽  
Ioan Gabriel Sandu ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Cast Iron ◽  
Point Of View ◽  
Industrial Scale ◽  
High Chromium ◽  
High Chromium Cast Iron ◽  
Brake Discs ◽  
Chromium Cast Iron ◽  
Analysis Point ◽  
Automotive Brake

We obtained a new Fe-C material, a cast iron with high chromium content. The experimental material was analyzed by microstructural (SEM electronic) and chemical (EDAX characteristic X-ray dispersive energy analysis) point of view. The addition of chromium is aimed to increase the corrosion resistance and durability of FC250 castings used on industrial scale in the manufacture of automotive brake discs. The material was obtained using an industrial scale furnace. The experimental results showed a substantial increase in corrosion resistance by the addition of chromium.

Study on the Corrosion Resistance of High Boron Iron-Based Alloy

2012 ◽  
Vol 268-270 ◽  
pp. 326-329 ◽  
Author(s):  
Ming Min Qiu ◽  
Hao Wang ◽  
Xu Wu ◽  
Hong Qun Tang ◽  
Guang Cai Su
Keyword(s):  
Corrosion Resistance ◽  
Cast Iron ◽  
Neutral Medium ◽  
Medium Ph ◽  
Wear Resistant ◽  
High Chromium ◽  
High Chromium Cast Iron ◽  
High Boron ◽  
Iron Based ◽  
Chromium Cast Iron

Being compared with traditional wear resistant materials, the corrosion resistance of high boron iron-based alloy at 25°Cand at 60°Care researched respectively. The results show that the corrosion resistance of wear-resistant alloys decline at high temperature. At 25°C and at 60°C, though the corrosion resistance of high chromium cast iron is a little higher than that of high boron iron-based alloy in acid medium (PH=3), high boron iron-based alloy’s corrosion resistance is the best among these three materials in neutral medium (PH=7) and in alkaline medium (PH=12).

Effect of Technology for Semi Solid State Cooling Plate on Primary Carbides and Mechanical Property of Hypereutectic High Chromium Cast Iron

2014 ◽  
Vol 556-562 ◽  
pp. 100-104
Author(s):  
Shi Bin Liu ◽  
Xiang Cai Meng ◽  
Hong Bo Li ◽  
Xing Ming Zhao
Keyword(s):  
Mechanical Property ◽  
Cast Iron ◽  
High Viscosity ◽  
Inclined Plate ◽  
High Chromium ◽  
High Chromium Cast Iron ◽  
Cooling Speed ◽  
Semi Solid ◽  
Primary Carbides ◽  
Chromium Cast Iron

In this paper, research the hypereutectic high chromium cast iron by the methed of semi-solid method for cooling inclined plate. Influence of cooling rate on size of primary carbides and mechanical property of hypereutectic high chromium cast iron. The results showed that, speed up the cooling speed can effectively refine eutectic primary carbides in hypereutectic high chromium cast iron. The primary carbides was globularity and slug, provided with excellent mechanical properties. But when the cooling speed is too fast, the pouring temperature is too low, so that the liquid metal has high viscosity, poor mobility. there were a small amount of inclusions in the Preparation of casting. Although still generate pieces of fine carbides in the matrix, but the distribution is not uniform. disadvantage of the comprehensive performance.

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