Microstructural evolution during austempering of a ASTM A-532 CLASS III type high chromium white cast iron undergoing abrasive wear

Abstract

This paper studies the influence of variables such as holding temperatures and times during austempering of High Chromium White Cast Iron (HCWCI), with the following chemical composition: Cr 25 %, C 3 %, Si 0.47 %, Mn 0.74 % and Mo 1.02 %. The aim of the austempering was to modify the percentage of retained austenite and its correlation to abrasive wear resistance under different conditions. Microhardness tests, SEM-EDS and XRD were performed to determine mechanical properties, chemical composition, and type of carbides and microstructures present, respectively. The tests complied with the ASTM G-65 standard. Results showed that the best performance against abrasion was achieved for austempering at 450 ºC with holding time of 6 hours.Keywords: Austempered; Retained austenite; Abrasive wear; High chromium white cast iron; Chromium carbides. ResumenEste trabajo estudia la influencia de variables tales como tiempo y temperatura de sostenimiento durante el austemperado de una fundición blanca al alto cromo con la siguiente composición: Cr, 25 %; C, 3 %; Si, 0.47 %; Mn, 0.74 %, y Mo, 1.02 %. El objetivo del austemperado fue modificar el porcentaje de austenita retenida, y * Ph. D. Universidad del Atlántico (Barranquilla-Atlántico, Colombia). oscarhiguera@mail.uniatlantico.edu.co. ORCID: 0000-0002-4836-5215. ** Universidad Tecnológica de Pereira (Pereira-Risaralda, Colombia). *** Universidad Tecnológica de Pereira (Pereira-Risaralda, Colombia). **** Ph. D. Universidad del Atlántico (Barranquilla-Atlántico, Colombia). monicamonsalve@mail.uniatlantico.edu.co. ORCID: 0000-0002-9902-8518. ***** Ph. D. Universidad Tecnológica de Pereira (Pereira-Risaralda, Colombia). dhmesa@utp.edu.co. Microstructural evolution during austempering of a ASTM A-532 CLASS III type high chromium white cast iron undergoing abrasive wear correlacionarlo con la resistencia al desgaste abrasivo bajo diferentes condiciones; los ensayos fueron realizados según los lineamientos de la norma ASTM G65. Las técnicas de microdureza MEB-EDS y DRX fueron realizadas para determinar las propiedades mecánicas, composición química, tipo de carburos y microestructuras presentes, respectivamente. Los resultados mostraron que la mejor resistencia a la abrasión fue alcanzada a una temperatura de austemperado de 450 ºC y a 6 horas de permanencia.Palabras clave: Austemperado; Austenita retenida; Desgaste abrasivo; Fundiciones al alto cromo; Carburos de cromo. ResumoEste trabalho estuda a influência de variáveis tais como tempo e temperatura de sustentabilidade durante o austemperado de uma fundição branca ao alto cromo com a seguinte composição: Cr, 25 %; C, 3 %; Si, 0.47 %; Mn, 0.74 %, e Mo, 1.02 %. O objetivo do austemperado foi modificar a porcentagem de austenita retida, e correlacioná-lo com a resistência ao desgaste abrasivo sob diferentes condições; os ensaios foram realizados segundo as diretrizes da norma ASTM G65. As técnicas de microdureza MEB-EDS e DRX foram realizadas para determinar as propriedades mecânicas, composição química, tipo de carbonet...

Microstructural Characterization of a Component Manufactured by Hybrid Casting of Two Different Ferrous Alloys

“…Matsubara et al 11 studied different HCCI containing 20%Wt of carbide-forming elements. Alloys with lower Cr and higher V, Mo and W also showed MC and M2C, while in the higher Cr (17%Wt) alloy the pro-eutetic M7C3 carbide was formed, followed by a L → M7C3 + austenite eutetic reaction 12 . Doğan et al 13 investigated hypoeutetic, eutetic and hypereutetic HCCIs, containing 15% or 26%Wt Cr.…”

“…Figure 7 shows the hardness maps made across the entire sample and in the interface region. Hardness values for the carbides vary between 1200-1800 HV, which indicates that they can be both transverse and longitudinal M7C3 carbides 12 . At the interface, there is a gradual increase in hardness, where in the WCB there is an average hardness of 200 HV, as we advance in the interface the hardness increases to 500-700HV until reaching the HCCI, where the martensitic matrix with chromium carbides is responsible for the very high hardness 1,[9][10][11] .…”

Protection of carbon steel from wear by quenching with nanotechnology to use it in dies parts

“…Specifically, Figure 5-a shows the wear rate at 20N of medium carbon steel quenching without nanoparticles was (15*10 -5 g/cm). But a decrease in the wear rate was observed when this steel quenching with different percentages of nanoparticles in quenching media (0.2, 0.4, and 0.6 %) at sliding speed of 0.5 cm/s to be (14*10 -5 , 11*10 -5 , and 13*10 -5 (g/cm), respectively, due to the formation of rugged structure [13]. This hard structure is martensite, as will be discussed later.…”

“…That means the soften of asperities reduces the forces required to shear points and improves wear resistance[12]. This improvement of wear resistance for specimens with nanoparticles in oil at the same temperature is due to the formation of the martensite phase, a very rigid structure[13]. The quenching with nanofluid causes refined microstructure that…”