Jiandong Xing

Investigation of quenching effect on mechanical property and abrasive wear behaviour of high boron cast steel

Abstract The effect of quenching temperature from 900 to 1050°C on the microstructures, mechanical properties and abrasion resistance of modified high born cast steel containing 0·3 wt-%C and 3·0 wt-%B was studied by optical microscopy, scanning electron microscopy, X-ray diffraction analysis, tensile tester, impact tester, hardness tester and abrasion tester. Quenching at 900°C resulted in structures containing a small amount of pearlite. The existence of pearlite led to poor hardness and wear resistance of modified high born cast steel. Quenching at temperatures between 900 and 950°C resulted in the decrease in pearlite and the increase in hardness and abrasion resistance in comparison with 900°C quenching. The metallic matrix all transformed into the martensite quenching at 1000°C; the modified high born cast steel had high hardness, tensile strength, impact toughness and excellent abrasion resistance. The hardness, tensile strength and impact toughness of modified high born cast steel had no obvious change quenching over 1000°C. The increase in quenching temperature also led to the transformation of boride from continuous shape to isolated shape and promoted the coarsening of boride.

Effect of rare earth–aluminium additions on the microstructure of a semisolid low carbon Fe–B cast alloy

Abstract The present study investigates the effects of rare earth and aluminium on the microstructures of as cast and heat treated semisolid Fe–B cast alloys. The as cast microstructure of the semisolid modified Fe–B cast alloy consists of the eutectic boride, pearlite and ferrite. Moreover, compared to a net-like distribution of the coarse eutectic borides in the ordinary unmodified alloy, the eutectic boride structures in the semisolid modified alloy are greatly refined and less interconnected. After heat treatment, the phases in the semisolid modified Fe–B cast alloy consist of the boride and martensite. The additions of rare earth and aluminium help to promote the formation of the short rod shaped and round borides in the semisolid Fe–B cast alloy during heat treatment. Compared to the ordinary unmodified alloy, there is no significant change in the boride area fraction but an obvious decrease in average boride area in the semisolid modified alloy.

Erosion–corrosion interaction of Fe–B alloy in flowing zinc

The effect of erosion angle on the erosion–corrosion interaction of Fe–3.5 wt-%B alloy in flowing zinc was investigated. The total erosion–corrosion rate decreased linearly, whereas the pure erosion rate fluctuated slightly with increasing erosion angle, which was strongly dependent on the erosion–corrosion interaction. At an erosion angle of 0°, liquid zinc corrosion damaged the sample surface and facilitated erosion, which in turn increased corrosion via the removal of corrosion products. As the erosion angle increased, corrosion products accumulated and Fe2B flaked and cracked in front of the erosion interface, which resulted, in turn, in increased obstruction to the diffusion of liquid zinc. Accordingly, the erosion–corrosion interaction was reduced, thereby resulting in a low material loss at high erosion angles.

Artificial neural network prediction on wear properties of high vanadium high speed steel (HVHSS) rolls

Abstract The present paper is dedicated to the application of artificial neural networks in the prediction of the wear properties of high vanadium high speed steel (HVHSS) rolls, including predictions of wear weight loss W according to carbon content C and number of revolutions N. Multilayer backpropagation networks were created and trained using comprehensive datasets tested by the authors. Very good performances of the neural networks were achieved. The prediction results show that the wear weight loss nearly linear increases with increasing number of revolutions at constant carbon content. The relative wear resistance of roll reaches the optimal value when the carbon content is ∼2·55 wt-%. The prediction values have sufficiently mined the basic domain knowledge of wear process of HVHSS rolls. A convenient and powerful method of optimising the process parameters of abrasive resistant materials has been provided by the authors.

Effect of Ti addition on morphology and size of primary M7C3 type carbide in hypereutectic high chromium cast iron

Abstract Effect of Ti addition on the morphology and size of primary M7C3 type carbide in hypereutectic high chromium cast iron was investigated. The results indicated that the carbide is refined gradually, and its morphology becomes more equiaxed as titanium addition increases, but rather slowly when Ti addition exceeds 0·95%. The qualitative measurement result indicated that value shape factor K increases clearly first and then changes little, and the average equivalent diameter D changes against K exactly. Furthermore, by TEM analysis and Brammit’s theory calculation, the results also indicated that there are orientation relationships of TiC||M7C3 and [011]TiC||[0001]M7C3 between M7C3 type carbide and TiC, and the lattice misfit δ between TiC and M7C3 is 1·32%, explaining that TiC may provide the effective substrate plane for M7C3 nucleation to ameliorate morphology and size of primary M7C3 type carbide.

A Study of Boron-Bearing Wear-Resistant Alloy Steel Liner

This article reports the results of an experimental program aimed at improving ball mill availability by increasing the wear resistance of ball mill liners. The ball mill liners made from the wear-resistant alloy steel containing 0.8–2.0 wt%B (viz. boron alloy steel) have been developed. The effects of quenching temperature on the microstructural modification, mechanical properties, and wear resistance of boron alloy steel have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis, impact tester, hardness tester, and impact wear tester. The results show that the hardness of boron alloy steel increases, and impact toughness has no obvious change, when the quenching temperature increases. When the quenching temperature reaches 1000°C, the matrix of boron alloy steel transforms into the lath martensite, and there is excellent wear resistance. After quenching at 1000°C and tempering at 220°C, boron alloy steel liners have excellent wear resistance and do not break in the use. Its servicing cycle is 1.6 times longer than that of high manganese steel liner. Boron alloy steel liner does not contain valuable alloy elements and has simple production process and low production cost.

Investigations on the Cast Boron Steel Guide Roller and Its Application in Steel Wire-Rod Mill

A new type of abrasion-resistant cast boron steel was developed based on the service conditions of the guide roller in the high-speed steel wire-rod mill. The lath martensite was its matrix and the broken Fe2B and dispersive distributed TiB2 were its wear resistant skeleton. The tensile strength, hardness, and impact toughness of cast boron steel quenched at 1000°C excel 750 MPa, 54 HRC, 14 J/cm2, respectively. The guide roller made of this steel has high strength and wear resistance and excellent thermal fatigue resistance and it is reliable to use in the high-speed steel wire-rod mill. Its service life is 1.133 times longer than that of cast high chromium nickel alloy steel and corresponding to that of the sintered-carbide.

Hot deformation and processing maps of Fe–B alloy

Abstract The hot deformation behaviour of Fe–B alloy under hot compression conditions has been investigated in the temperature range of 1000–1075°C and strain rate range of 0·01–4 s−1. The results show that the maximum stress decreases with decreasing strain rate and increasing temperature, and the activation energy is 573·68 kJ mol−1. Processing maps are developed on the basis of experimental data and using the principles of dynamic materials model. The peak power dissipation efficiency domain occurs roughly in the temperature range of 1045–1075°C and strain rate range of 0·02–0·3 s−1 with a peak efficiency of power dissipation of ∼0·5, which is the optimal processing region for the investigated alloy. Microstructural observations reveal that the dynamic recrystallisation occurs in the domain. The alloy also exhibits flow instability in the temperature range of 1000–1075°C and higher strain rate (>0·5 s−1).