Influence Of Austenitizing Temperature Research Articles

Influence of Austenitization Temperature on Tensile Properties and Impact Toughness of Niobium Micro-alloyed Carbide-Free Bainitic Steel

Influence of Austenitization Temperature on Tensile Properties and Impact Toughness of Niobium Micro-alloyed Carbide-Free Bainitic Steel

The influence of austenitization temperature on microstructural developments, mechanical properties, fracture mode and wear mechanism of Hadfield high manganese steel

In this investigation, the effect of austenitization temperature on microstructural evolution, mechanical properties, fracture mode, and wear mechanism of a high carbon Hadfield steel was studied. Four blocks of the Hadfield steel were cast in an induction furnace. One hour austenitization was performed at 1000 °C, 1075 °C, 1150 °C, and 1225 °C on the cast samples followed by quenching in water. Uniaxial tensile test, pin on disk wear test and Vickers hardness measurements were employed on the processed samples. An optical microscope and a field emission scanning electron microscope were used to study the microstructural evolution. Transmission electron microscope was employed to observe the carbides that were formed. Moreover, scanning electron microscopy technique was used to define the mode of fracture on the tensile test samples. Results showed that increasing austenitization temperature reduced carbides and increased austenite grain size. Mechanical properties measurements also showed that increasing austenitization temperature increased yield/tensile strengths, hardness, and wear resistance of this steel. However, these increments were made at the expense of ductility. Fractography results showed a very ductile mode of fracture. The share of the ductile fracture mode was further increased by reducing the austenitization temperature from 1225 °C to 1000 °C.

The influence of austenitization temperature on phase transformations of supercooled austenite in low-alloy steels with high resistance to abrasion wear

The paper presents continuous cooling transformation (CCT) diagram of selected low-alloy steel with high resistance to abrasion. Samples were prepared from examined material in as delivered conditions, then were austenitized at 900, 1000, 1100 and 1200°C for 20min, and then cooled with the rates of V800–500=50, 10, 5, 1, 0.5, 0.1°C/s. During the dilatometric research, the critical temperatures were defined as well as the critical points specified for different cooling rates were designated. In addition, metallographic documentation of received microstructures after dilatometric investigations was prepared and hardness measurement was performed. The increase in the austenitizing temperature caused changes in the temperature of MS and in the size of the martensite laths. What is more, the increase in the austenitizing temperature in the case of the analyzed steel caused a displacement of the bainitic and diffusion transformations to longer times. During the analysis using the TEM and SEM it was found that the size of the austenite grains is largely controlled by precipitates of the nitrides of AlN, TiN and carbides, mainly Cr7C3 and M23C6.

EFFECTS OF AUSTENITIZATION ON STRUCTURE FORMATION СHROMO-MOLYBDENUM-VANADIUM STEEL AFTER HIGH TEMPERING

Influence of austenitization temperature of chrome-molybdenum-vanadium steel on structure formation at the softening heat treatment is studied. It is shown that the decline of the austenitization temperature promotes to reduce the micro-hardness values due to the intensification of spheroidizing of pearlite after the overcooling and high tempering. Increasing the austenitization temperature leads to formation of an uneven structure after tempering.

Effect of Austenitization Temperature on Formation of Low Temperature Bainite

The influence of austenitization temperature on the incubation period and bainitic transformation behaviours of the high-carbon silicon steel has been investigated. It was found that the nose temperature of bainite transformation and incubation period decreases with increasing austenitization temperature. The microstructure characteristics of the bainitic transformation products have been also observed. After isothermal heat treatment at 230°C for 20 mins, all samples austenitized at different temperatures produced a bainitic structure, which consists of packets of parallel ferrite laths. The major difference lies in the edge boundary morphology. Bainitic laths formed in low-temperature austenitization conditions has sharp saw-tooth edge boundaries, whereas bainite transformed from high-temperature austenitization conditions, have smooth wedge boundaries. Key Words: austenitization temperature; low-temperature bainite; incubation period;edge boundary

Influence of austenitization temperature on phase transformation features of modified high Cr ferritic heat-resistant steel

The phase transformation features of high Cr ferritic heat-resistant steel have been investigated using Differential Thermal Analysis (DTA) in accordance with different austenitization temperatures as 950°C, 1050°C, 1150°C, 1200°C and predicted by Thermo-calc calculation. The results based on DTA curves on heating showed that the magnetic transition and the Ac1 temperature occurred at 744.9°C and 850.9°C, respectively. The measured Ac3 temperature was around 919.5°C, the obtained austenitization temperature range was about 69°C. Two new phenomena were found: firstly, the onset temperature of martensite transformation increases strongly and then not obviously with the increase of austenitization temperature; secondly, the δ-ferrite abnormally forms in the specimen austenitized at 950°C due to the existence of un-dissolved M23C6 particles.

The Influence of Austenitization Temperature on the Mechanical Properties of a Prehardened Mould Steel

The many practical difficulties and longer lead time with heat treatment of mould steels after machining have led to increased demand for steels in prehardened condition, typically ~ 40HRC. At this hardness the steel possesses an optimal combination of high strength and machinability. The steels used for moulds require a wide range of demanding properties, among which high enough strength and toughness are the primary necessities in order to resist any deformation and dimensional change in mould during use. Uddeholm Impax HH which resembles the modified AISI P20 has been widely used for moulding of plastics and die-casting of low melting temperature metals. The common hardening process for Impax HH is conventional quenching and tempering. Hence, investigating the effect of hardening parameters on the required properties upon this steel grade is beneficial in improving it for better performance as a prehardened mould steel. In the present work, the effect of changes in austenitization temperature and consequently the prior austenite grain and martensite packet sizes on the tensile properties and impact toughness of Uddeholm Impax HH at the hardness of ~40HRC is studied. The results have shown reduction in impact toughness but no considerable change in yield and ultimate tensile strength upon increasing the austenitization temperature.

Influence of austenitization temperature on the micromechanism of failure of structural steels in the temper brittleness condition

Influence of austenitization temperature on the micromechanism of failure of structural steels in the temper brittleness condition