Grain size strengthening in steel and its relationship to grain boundary segregation of carbon

Abstract

Afield ion atom probe study has been made of a low carbon steel after furnace cooling and rapid quenchingfrom 700°C. Marked segregation of carbon to the boundaries was observed after furnace cooling, but not after rapid quenching. From comparison of previous and present results, it is concluded that the ky value of a steel can be related to the interstitial impurity content (mainly carbon) at the grain boundaries. Heat treatments that, encourage grain boundary segregation of interstitials will result in steels having a high ky value.MSTj1569

Mechanisms of subgrain coarsening and its effect on the mechanical properties of carbon-supersaturated nanocrystalline hypereutectoid steel

“…the annealed materials are stronger than the cold-drawn wires for the same subgrain size. The k HP value, which is affected by the carbon concentration at the grain boundary, has been reported to be in the range between 315 and 760 MPa lm 0:5 [46][47][48][49][50]. While the ferrite grain size investigated in the literature was in the micrometer range [46][47][48][49][50], it is interesting to observe that the current value observed in the nanocrystalline steel also falls in the reported range.…”

Influence of nitride formers on strength and impact behaviour of hot rolled steel

“…Mn lowers the activity of carbon and so if it segregates to the boundaries as has been noted in the previous atom probe study on plain C-Mn steels, 18 it would be expected to increase the C there. Hence, higher Mn steels by attracting more C to the boundaries might be expected to make it more difficult to generate dislocations from the boundaries leading to a larger influence on impact behaviour, when this segregation is reduced by elements which increase the activity of carbon.…”

Experimental characterisation in sheet forming processes by using Vickers micro-hardness technique

“…The bobbing temperature consists in an own thermal treatment of reheating the sheet. It has a particular effect on grain size and precipitates that can be developed during process progression [10,11]. The distribution of matrix material contents is firstly a function of present elements quantities in the HSLA steel and secondly it is a function of the rolling conditions, which play great actions in microstructure evolution during each step of the rolling cycle.…”