0086-21-58386256
Dwell times given in bold characters (column 5 in Table 1) indicate the values for processing window of the examined alloy, i.e., the optimum austempering heat …
According to Bayati and Elliott [ 9 ], the optimal processing window (OPW) is the time between the stage I (γ → γ r + α, bainitic reaction) and stage II (γ r → α+carbide) where the austempering process takes place and the volume of unstable austenite falls to 1% without presence of martensite.
The processing window defines the austempering time interval during which optimum properties can be obtained. Bahmani and Elliott [3] demonstrated that the start of the processing window is defined as the austempering time at which the amount of martensite is reduced to 3%.
The aim of the paper was to investigate the effect of austempering parameters (time and temperature) on the microstructure and mechanical properties of …
The CADIs austempered at 305 • C showed similar tensile strength, in the range from 818 to 802 MPa, while the yield strength was in the range from 697 to 686 for the chromium additions of 0.2 and...
Austempering is performed over the temperature range of 230-450 °C according to the expected properties of the components. The holding time at the austempering temperatures depends on the various parameters and can be altered between 0.5 up to several hours.
As a result of further step of austempering within processing window, optimum ausferrite with maximum amount of fine acicular ... then completed at 350, 390 °C (step-up) for a time specified by TTT diagram; Austempering at 350, 390 °C in a few short time intervals, necessary to proceed from 5% to approx. 40% of transformation, then …
Effect of Graphite Nodularity on microstructure and processing window of 1.5% Ni-0.3% Mo austempered cast iron
Microstructure changes during austempering at 440 °C for 150 min after austenitising at 900 °C for 120 min. (a) 95%, (b) 77%, (c) 52%, and (d) 21% graphite nodularity. Download : Download full-size image Fig. 6. Variation of retained austenite content with austempering at 440 °C austempering temperature for given graphite …
Processing Window - Explore the topic Processing Window through the articles written by the best experts in this field - both academic and industrial - ... AbstractMeasurements of the austempering kinetics and mechanical properties are presented for a ductile iron of composition Fe–3·51C– 2·81Si–0·25Mn–0·39Cu–0·13Mo–0·04Mg (wt ...
effect of austempering parameters (time and temperature) on the microstructure and mechanical properties of ADI alloyed with 0.45% Cu in order to establish the optimal processing window.
The standard processing window depends on the austempering parameters and alloying elements, as well as the method used to produce ADI.
This work aims to determine the process window (PW) of two austempering temperatures (265 and 305 C) to identify the optimum austempering parameters that increase the mechanical properties of the ductile irons alloyed with 0.2 and 0.3 wt % V for the camshaft manufacturing.
Equally important is the identification of process control and quality assurance factors to achieve the desired properties successfully and consistently.ln this study, aspects of austempered ductile iron quality control are reviewed including the production of quality ductile iron that will respond to austempering heat treatments, heat ...
Two-step "high–low", (400– 320°C) temperature austempering produced a mixture of upper and lower ausferrite matrix microstructure. An improvement in the elongation to fracture and impact properties was observed after 400–320°C two-step processing. Download Free PDF View PDF Materials & Design
According to Bayati and Elliott, the optimal processing window (OPW) is the time between the stage I (γ → γ r + α, bainitic reaction) and stage II (γ r → α+carbide) where the austempering process takes place and the volume of unstable austenite falls to 1% without presence of martensite. Based on this definition, the OPW is lessened ...
The Austempering Kinetics, Microstructural Development and Processing Window in the Austempered, FE-3.2C-4.8AL Compacted Graphite Cast Iron A. Kazazi, …
Different austempering times were selected to obtain a variation in content of austenite and acicular ferrite at this temperature and to find out the optimum conditions, so that the processing window for both the alloys could be established.
The alloys were then austenitized with the same conditions at 875 °C for 2 h and austempered for three different combinations of temperatures and times: 250 °C for 6 h, 310 °C for 3 h and 380 °C for 1 h.
An investigation has been conducted on two austempered ductile irons alloyed with Cu and Cu + Ni, austenitized at 900 deg. C and austempered at 350 deg. C. The microstructure and fracture mode developed through these treatments have been identified by means of light and scanning electron microscopy and X-ray diffraction analysis.
austempered microstructure [2-5] which, in turn, is a function of austempering time and temperature. The optimum mechanical properties for austempered ductile iron can be achieved if the heat treatment is conducted in a restricted time and temperature frame called the "processing window" [6]. Determining the processing window by …
The austempering times were selected to be 20, 40, 80, 160 minutes. It is of interest to mention that Quenching from austentizing temperature to the salt bath should be rapid enough to avoid any Transformation of the austenite to ferrite or pearlite.
Optimum properties were obtained at shorter austempering times in both sets, with the lower austenitizing temperature suggesting a wider processing time window. The …
The aim of the paper was to investigate the effect of austempering parameters (time and temperature) on the microstructure and mechanical properties of ADI alloyed with 1.5% Cu and 1.6% Ni (in wt.%)… Expand 21 Influence of graphite nodularity on microstructure and processing window of 1.5% Ni-0.3% Mo austempered cast iron
According to Bayati and Elliott, the optimal processing window (OPW) is the time between the stage I (γ → γ r + α, bainitic reaction) and stage II (γ r → …
The optimum austempering period is the duration between the end of the first reaction and the beginning of the second, which is sometimes re- ferred to as the processing window. The influence of the microstructure of ADI on tensile properties is …
Austempered ductile iron (ADI) proved to be an advanced material as it possesses remarkable combination of high strength, ductility and toughness with good wear resistance and machinability. These properties can be achieved upon adequate heat treatment which yields optimum microstructure for a given chemical composition.
It is shown that optimum mechanical properties are achieved with a fully ausferrite structure of ferrite and high C austenite. The heat treatment processing …
The selection of the right austempering time enables achieving an optimal, purely ausferritic metallic matrix (that is, a mixture of ferrite plates and high-carbon stable austenite). ... R. Austempering of low manganese ductile irons. Part 1 Processing window. Mater. Sci. Technol. 1993, 9, 572–585. [Google Scholar] Darwish, N.; Elliott, R ...
The alloys were then austenitized with the same conditions at 875 °C for 2 h and austempered for three different combinations of temperatures and times: Ductile irons were produced into different casting wall sections, that is, 25 mm, 5 mm and 3 mm.
Heat treatment cycle included austenitization at 950 °C for 30 min in air followed by direct transfer (with no time lag) to salt bath furnaces for austempering in the range 250–400 °C for time period up to 120 min before quenching in …
It is shown that optimum mechanical properties are achieved with a fully ausferrite structure of ferrite and high C austenite. The heat treatment processing window is defined as the austempering time interval over which the mechanical properties satisfy the ASTM A897M: 1990 ADI standard.
The standard processing window depends on the austempering parameters and alloying elements, as well as standard used. The ISO and EN standards give a …
In the literature (13), this time is referred to as the first stage of the austempering transformation. The second stage, in which there is a two-phase austenitic-ferritic metallic matrix, covers a period of 120 to 180 min.
The time period between the end of Stage I f1132 Olivera Eric Cekic et al. and the start of Stage II is called the processing window (PW). on a 50 kN ZDM 5/91 tensile testing machine, with a constant The PW defines the austempering time interval, t2-t1. The cross-head travel speed of 1 mm/min.
Austempering heat treatment consisted of austenitizing at 875° for 90 min followed by austempering at three different temperatures of 320, 365 and 400°C. Rotating-bending fatigue test was carried out on samples after shot peening by 0.4-0.6 mm shots.