Effects of cryogenic treatment on microstructure and abrasion resistance of CrMnB high-chromium cast iron subjected to sub-critical treatment

Liu, Haohuai; Wang, Jun; Yang, Huihui; Bao-luo, Shen

doi:10.1016/j.msea.2007.06.012

Cited by 58 publications

(32 citation statements)

References 11 publications

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“…In order to obtain a better wear performance, the high chromium white cast irons should present a martensitic structure, because the martensitic formation, compared to the austenitic, minimizes cracking and removal during wear. While it was considered that the presence of residual austenite in the microstructure causes volumetric expansion which may also lead to microcracks because of the developed stresses, some investigations determined that a certain percentage of retained austenite could improve the abrasion resistance, due to its work-hardening properties [3,4], ductility and thermodynamic metastability at room temperature [5]. According to Liu et al [6] the best abrasion resistance is obtained when the content of retained austenite is higher than 20%.…”

Section: Introductionmentioning

confidence: 99%

Mejoramiento de la resistencia al desgaste abrasivo de la fundición al alto cromo ASTM A-532 a través de ciclos de tratamiento térmico

2016

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High-Chromium White Cast Iron is a material highly used in mining and drilling shafts for oil extraction, due to its high wear resistance. However, because of the austenitic matrix found in the as-cast state, an adequate heat treatment cycle is necessary. This paper studies the effects of different cooling media after a destabilization treatment on the microstructure, hardening and abrasion resistance behaviors of a hypoeutectic high chromium white cast iron. The results show that although air cooling followed by immersion in CO 2 can effectively reduce the retained austenite, this is not enough to transform completely the retained austenite into martensite. The low retained austenite percentages improve bulk hardness, but they decrease the abrasion resistance of the high chromium cast iron. The best combination of hardness and wear resistance was found in the samples cooled in air, due to the percentage of retained austenite and a moderate precipitation of chromium carbide.Keywords: High chromium white cast iron, HCWCI, White cast iron, Chromium carbides, Hardness, Wear testing, Austenite, Martensite. Improvement of abrasive wear resistance of the high chromium cast iron ASTM A-532 through thermal treatment cycles ResumenLas fundiciones blancas de hierro al alto cromo son muy usadas en la minería y en la perforación de pozos petroleros, debido a su alta resistencia al desgaste; sin embargo, debido a que en el estado de colada su microestructura es austenítica, es necesario someterlas a un adecuado ciclo de tratamiento térmico. Este trabajo estudia los efectos de los diferentes medios de enfriamiento después de un tratamiento de desestabilización de la microestructura y, por ende, el efecto del grado de endurecimiento sobre el comportamiento a la abrasión de una fundición blanca al alto cromo hipoeutéctica. Los resultados muestran que a pesar de que el enfriamiento al aire, seguido por inmersión en CO 2 , puede reducir eficazmente la austenita retenida, esto no es suficiente para transformarla completamente en martensita. El bajo porcentaje de austenita retenida incrementa la dureza del material, pero disminuye la resistencia a la abrasión de las fundiciones al alto cromo. La mejor combinación de dureza y resistencia al desgaste se encontró en las muestras enfriadas al aire, debido al porcentaje de austenita retenida y a una moderada precipitación de carburos de cromo.Palabras clave: HCWCI, Fundiciones blancas de hierro, Fundición al alto cromo, Carburos de cromo, Austenita, Martensita. ResumoAs fundições brancas de ferro ao alto cromo são muito usadas na mineração e na perfuração de poços petroleiros, devido a sua alta resistência ao desgaste; porém, devido a que no estado de lingotamento sua microestrutura é austenítica, é necessário submetê-las a um adequado ciclo de tratamento térmico. Este trabalho estuda os efeitos dos diferentes meios de resfriamento depois de um tratamento de desestabilização da microestrutura e, consequentemente, o efeito do grau de endurecimento sobre o comportamento à abrasão ...

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Section: Introductionmentioning

confidence: 99%

Mejoramiento de la resistencia al desgaste abrasivo de la fundición al alto cromo ASTM A-532 a través de ciclos de tratamiento térmico

2016

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“…And Ostwald ripening is an observed phenomenon in solid solutions which describes small crystals or particles dissolve, and redeposit onto larger crystals or particles [2]. The microstructure was substantially disordered which caused by splat-cooling during deep cryogenic treatment, and this was conducive to release the microscopic stress.…”

Section: Effect Of Deep Cryogenic Treatment On Hardnessmentioning

confidence: 99%

“…Bainitic ductile irons have long been considered candidate materials for wear-resistant components in mining and minerals industry due to their excellent impact toughness, strength and abrasion resistance provided by the bainite, eutectic carbides and graphite in the microstructure [1,2]. There are two routes to obtain bainite microstructure.…”

Section: Introductionmentioning

confidence: 99%

Effect of deep cryogenic treatment and tempering on microstructure and mechanical behaviors of a wear-resistant austempered alloyed bainitic ductile iron

Chen

Cui

Tong

2015

MATEC Web of Conferences

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Abstract. In this paper, the effect of deep cryogenic treatment in combination with conventional heat treatment process was investigated on microstructure and mechanical behaviors of alloyed bainitic ductile iron. Three processing schedules were employed to treat this alloyed ductile iron including direct tempering treatment, tempering.+deep cryogenic treatment and deep cryogenic treatment.+tempering treatments. The microstructure and mechanical behavior, especially the wear resistance, have been evaluated after treated by these three schedules. The results show that martensite microstructure can be obviously refined and the precipitation of dispersed carbides is promoted by deep cryogenic treatment at .−196 • C for 3 h after tempered at 450 • C for 2 h. In this case, the alloyed bainitic ductile iron possesses rather high hardness and wear-resistance than those processed by other two schedules. The main wear mechanism of the austempered alloyed ductile iron with deep cryogenic treatment and tempering is micro-cutting wear in association with plastic deformation wear.

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“…Such heat treatments are very often either a high temperature destabilization treatment or a sub-critical treatment. [7][8][9][10] The sub-critical treatment has some specific advantages as it cuts down the cost of high temperature treatment and avoids distortions and fissuring of castings. 10) But even after such conventional heat treatments the retained austenite cannot be fully converted to martensite.…”

Section: Introductionmentioning

confidence: 99%

Effect of Sub-critical Tempering and Deep Cryogenic Treatment on Slurry Erosion of Cr–Mn–Cu White Cast Irons

2014

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The effect of deep cryogenic treatment and air cooling subsequent to sub-critical tempering treatment on the structural evolution and the resulting wear performance of Cr-Mn-Cu white cast iron in sand-water slurry media were studied. The as-cast matrix of Cr-Mn-Cu white cast iron is predominantly austenitic which can be transformed to a martensitic matrix embedded with fine M7C3 carbides, by a sub-critical tempering treatment followed by air cooling. But the retained austenite is not totally converted. Quenching of alloy in liquid nitrogen bath after subcritical tempering enables more amount of transformation of austenite with simultaneous homogeneous precipitation of fine carbides. The phase transformation and corrosionerosion behavior were characterized by optical and scanning electron microscopy, bulk and micro-hardness measurement and x-ray diffraction analysis, measurement of corrosion rate and slurry erosion test. The slurry erosive wear performance has been found to be much better in the cryotreated alloys compared to those with conventional sub-critically tempered alloys.

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Effects of cryogenic treatment on microstructure and abrasion resistance of CrMnB high-chromium cast iron subjected to sub-critical treatment

Cited by 58 publications

References 11 publications

Mejoramiento de la resistencia al desgaste abrasivo de la fundición al alto cromo ASTM A-532 a través de ciclos de tratamiento térmico

Mejoramiento de la resistencia al desgaste abrasivo de la fundición al alto cromo ASTM A-532 a través de ciclos de tratamiento térmico

Effect of deep cryogenic treatment and tempering on microstructure and mechanical behaviors of a wear-resistant austempered alloyed bainitic ductile iron

Effect of Sub-critical Tempering and Deep Cryogenic Treatment on Slurry Erosion of Cr–Mn–Cu White Cast Irons

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