Influence of quenching temperature of the individual quenching method on the geometrical dimensions of the elements

Abstract

The quenching process is related to the internal-stress phenomena, resulting in geometric changes (distortions). In this paper, the impact of hardening temperature on the quenching distortions occurring during low-pressure carburizing with gas quenching using the individual quenching method was analyzed. The reference elements were subjected to carburizing at 980°C, followed by gas quenching at temperatures of 860°C, 920°C and 980°C. The geometrical measurements of the elements were made before and after the chemical treatment and the size of the quenching distortions of their geometrical parameters was determined: external and internal diameters as well as ring thickness. The study examined whether there is a statistically significant difference between the geometrical dimensions of the elements before and after the thermo-chemical treatment for the elements in three temperature groups. It was shown that for the ring thickness parameter there are no significant differences between the groups of elements before and after heat treatment for the temperature 980°C, while for the temperature 860°C and 920°C these changes are significant. However, for external diameter bottom, there is always a difference regardless of temperature. For the single piece-flow vacuum carburizing with gas quenching using the individual quenching method, it is advisable to use the highest possible quenching temperatures to reduce quenching distortions.

Algorithm Scheme to Simulate the Distortions during Gas Quenching in a Single-Piece Flow Technology

“…The difference between the obtained results in terms of surface flatness of the outer and inner circles was the result of sample preparation for testing and, primarily, the quenching process. In the opinion of the authors, quenching from high temperatures results in the immediate occurrence of a martensitic transition and a "freezing" of the geometrical dimensions on the outer side of the element [10,14,15]. Consequently, the "deformation front" is pushed deep inside the element, and the inevitable changes in volume-related to transition of the material from austenite to martensite-take place in the inner parts of the element.…”

“…In the perspective of constructing a new device that gives optimized outcomes in minimizing distortions, this study developed a simulation around Vacuum UniCase Master (UMC ® ) Furnace design by SECO/WARWICK (Świebodzin, Poland) that uses low-pressure carburizing (LPC), followed by high-pressure gas quenching (HPGQ) in a 4D chamber (4D Quench ® ), all conducted using the single-piece flow method. LPC and HPGQ, when compared with traditional methods, have shown better results [8][9][10][11]. Moreover, the single-piece flow model takes every single element through the exact same position and process conditions as the others, avoiding variations in the physical and metallurgical characteristics over the placement that the element occupies [2,3,12,13].…”

Fatigue Characteritics of Medium Carbon Steel after Heat Treatment Using Sand as Cooling Media

“…The cooling media used in the heat treatment process is very diverse, including: water [2], [8]- [15], hot water [9], [14], [16], ice water [11], [16], palm kernel [12], oil [8][9], [12]-13], [15], [17], air [8]- [11], [18], gas [17], [19], polymer [2], sherol [2], aqueous 20% polymer solution [11], salt solution [13]- [14].…”