Hot Deformation Behavior of Bearing Steels

Abstract

The material behaviors of two types of bearing steels at hot working conditions are investigated. Stress-strain curves at various temperatures (900–1300°C) and strain rates (1–50/s) are obtained by compression tests with a computer controlled servo-hydraulic Gleeble 3800 testing machine. Elongation and reduction of the area are also obtained by tensile tests with the Gleeble 1500 testing machine. Flow stresses are calculated from the experiments and are used to predict the temperature distribution and the metal flow of a workpiece during a multistage hot forging process of a bearing race. A rigid-thermoviscoplastic finite element method is applied. The experimental and numerical results are summarized to reveal the reasons for internal crack formation.

Nonisothermal Austenite Grain Growth Kinetics in a Microalloyed X80 Linepipe Steel

“…[5][6][7][8][9] Sufficiently finely dispersed particles containing the microalloying elements, niobium, titanium, or vanadium, have been found to inhibit austenite grain growth effectively. [6,[10][11][12][13] During welding, particle dissolution or coarsening may occur in the HAZ depending upon the thermal cycle. The associated change in average particle size and volume fraction reduces the pinning force and may, thus, play a crucial role in controlling the austenite grain size in the HAZ.…”

Analysis Of The Austenite Grain Growth In Low-Alloy Boron Steel With High Resistance To Abrasive Wear

“…Austenite grain size strongly influences the kinetics of phase transformation during the cooling cycle [3,4]. Some investigations on the grain growth kinetics for low carbon steel and microalloyed steel have been already reported [4][5][6] but still some efforts have to be expended to understand the grain growth behavior and influence of alloy addition on the grain growth in low-alloy boron steels with high resistance to abrasive wear. With this state of knowledge it is necessary to study the effect of heating temperature and holding time on the growth of the austenite grains in low-alloy steels with boron intended to heat treatment.…”

Predictive Model for Austenite Grain Growth during Reheating of Alloy Steels

“…Several empirical models based on Arrhenius-type equations have been reported to predict the austenite grain growth for plain-carbon and low-alloy steels: 20,24) ... where R is a gas constant (8.314 J/mol/K), T is the reheating temperature in Kelvin, t is the holding time in second, and each alloying element is expressed in terms of its weight percentage. The grain diameter d is in micrometer.…”

“…Experimental data on AGS over wide ranges of chemical composition and reheating conditions were collected from literature; 1,2,4,[8][9][10][13][14][15][16][17][18][19][20][21][22][23][24]27,28,30,31) the 457 data collected are summarized in Table 1 …”