Showing papers on "Austempering published in 1978"
TL;DR: This article showed that deformed austenite transforms to upper bainite at temperatures at least as low as 200°C due to enhanced nucleation and/or growth at slip band heterogeneities generated by the defor-mation process.
Abstract: Deformation of austenite containing 0.85 pct C is shown to significantly increase the ten-sile strength of bainite formed during subsequent transformation. Quantitative metallo-graphic measurements indicate that strengthening is due primarily to an increased dislo-cation density in the ferrite and reduced carbide size, with consequent finer distribution, compared with the bainite formed from undeformed austenite. It is also shown that de-formed austenite transforms to upper bainite at temperatures at least as low as 200°C due to enhanced nucleation and/or growth at slip band heterogeneities generated by the defor-mation process while the only effect on the formation of lower bainite is a retardation of the transformation and reduction of ferrite plate size.
39 citations
Patent•
15 Nov 1978TL;DR: A lower bainite alloy steel article particularly suitable for gears, bushings and the like includes carbon in the range of 0.60 to 0.80 Wt. as mentioned in this paper.
Abstract: A lower bainite alloy steel article particularly suitable for gears, bushings and the like includes carbon in the range of 0.60 to 0.80 Wt.%, manganese in the range of 0.45 to 1.00 Wt.%, silicon in the range of 0.15 to 2.20 Wt.%, molybdenum in the range of 0.40 to 0.70 Wt.%, and the balance substantially iron. A process of heat treatment of the article includes the steps of quenching it from a first temperature at a preselected rate and of holding it at a second temperature for less than about two hours to complete transformation of the alloy directly from an austenite morphology to a substantially complete low temperature bainite morphology.
16 citations
TL;DR: The thermal stability of upper bainite is manifest as high stability of retained Austenite and retention of rather large quantities of austenite after prolonged high-temperature tempering as mentioned in this paper.
Abstract: 1.
Decomposition of supercooled austenite in the upper temperature range of the bainitic transformation leads to formation of structures with a stable system of defects that determine the thermal stability of upper bainite during subsequent heating.
2.
Upper bainite is highly resistant to recrystallization in comparison with martensite, which is characteristic of polygonized structures.
3.
The thermal stability of upper bainite is manifest as high stability of retained austenite and retention of rather large quantities of austenite after prolonged high-temperature tempering.
4.
The structural characteristics of upper bainite have a substantial effect on the mechanical properties of steel after high-temperature tempering.
1 citations
Patent•
15 Nov 1978TL;DR: A lower bainite alloy steel article particularly suitable for gears, bushings and the like includes carbon in the range of 0.60 to 0.80 Wt. as mentioned in this paper, silicon and molybdenum, and the balance substantially iron, and a process of heat treatment of the article includes the steps of quenching it from a first temperature at a preselected rate and of holding it at a second temperature for less than about two hours to complete transformation of the alloy directly from an austenite morphology to a substantially complete low temperature bainites morphology.
Abstract: A lower bainite alloy steel article particularly suitable for gears, bushings and the like includes carbon in the range of 0.60 to 0.80 Wt.% manganese in the range of 0.45 to 1.00 Wt.%, silicon in the range of 0.15 to 2.20 Wt.%, molybdenum in the range of 0.40 to 0.70 Wt.%, and the balance substantially iron. A process of heat treatment of the article includes the steps of quenching it from a first temperature at a preselected rate and of holding it at a second temperature for less than about two hours to complete transformation of the alloy directly from an austenite morphology to a substantially complete low temperature bainite morphology.