Jominy test applied to PM steels for heat treatment

Abstract

The hardenability of some PM steels designed for heat treatment has been evaluated on sintered steel specimens by applying the procedure standardised with the Jominy end quench test. The samples have been produced using two types of commercial powders, frequently selected for exacting applications. Manufacturing process includes admixing with graphite and lubricant, compaction at about 7 . 0 g cm 23 density and sintering at 1393 K for 30 min in industrial equipment. In order to investigate the thermal behaviour of the tested steels, during the cooling after austenitising, the temperatures inside the Jominy samples at different positions have been recorded. Hardness values and cooling rates have been correlated to an in depth microstructural analysis and microhardness profiles, finding a good agreement. The results can be utilised for a more reliable applications.

Critical aspects of sinter-hardening of prealloyed Cr–Mo steel

“…There are some complications to the Jominy hardenability test intended for PM material (Bocchini et al, 2006;Sokolowski and Lindsley, 2009). The importance of austenitization temperature on the result of the Jominy test for high molybdenum containing steels has been pointed out (Sokolowski and Lindsley, 2009).…”

Bainite morphologies in sintered steels: influence of materials and process conditions

“…In this regard, it must be borne in mind that the beliefs spread up more than 30 years ago [20] were disproved by experimental researches conducted by Saaritas et al. [21] and, shortly afterwards, by Bocchini et al [22–24], Those researches demonstrated that the cooling speed within a sintered PM part is higher than that of an analogous part, made of fully dense steel, and increases as density decreases. According to Bocchini [25] the explanation is as follows: … the heat flux from the cooling part – other conditions being equal – occurs through the outer surface.…”

Stable and Unstable Crack Growth in Chromium Pre-Alloyed Steel

“…Moreover, the dimension and morphology of the microstructure strongly affect the fatigue crack behaviour of the steels [2][3][4][5]. The nature of porosity and the metallographic phases are influenced by several processing variables, such as the type and amount of alloying additions, the sintering temperature and time, the cooling rate after sintering or the presence of heat treatments after sintering [6][7][8][9][10]. In this paper fatigue tests were performed on steels from Astaloy CrM powders to investigate the threshold zone and to evaluate the Paris law, varying the sintering temperature and the cooling rate in the furnace after sintering.…”