High temperature SANS experiments on Nb(C,N) and MnS precipitates in HSLA steel

Abstract

The volume distribution of precipitates in high-strength low-alloy (HSLA) steels has been studied using small-angle neutron scattering (SANS) at high temperatures. Three samples with different niobium concentrations (0.00, 0.05, and 0.10 wt pct) were slowly heated from a temperature of 910 ЊC to 1200 ЊC. With increasing temperatures, the scattered intensity strongly decreases as the precipitates gradually dissolve or coarsen. A comparison between the particle distribution of the three different materials suggests that the particles with a radius below 10 nm mainly correspond to Nb(C,N) precipitates and the larger particles to MnS precipitates. Subsequent cooling from 1200 ЊC to 910 ЊC only leads to a small increase in the scattered intensity. Quenching from the austenite to the ferrite phase and reheating to the austenite phase, however, produces a large increase in the formation of the small precipitates with a radius below 10 nm.

Thermomechanical processing route to achieve ultrafine grains in low carbon microalloyed steels

“…As expected, the increased supersaturation led to a higher driving force for precipitation in both Nb and Nb-Ti steels [29,30]. Furthermore, the volume fraction of SIP and its average diameter was also directly influenced by the amount of deformation.…”

In situdetermination of aging precipitation in deformed Fe-Cu and Fe-Cu-B-N alloys by time-resolved small-angle neutron scattering

“…By applying a strong magnetic field to the specimen, these two components could be separated. 15,16 For a dilute system of particles embedded in a homogeneous matrix, the macroscopic differential scattering cross section ͑d⌺ / d⍀͒ characterizes the scattering power by 16,36 …”

Low temperature precipitation kinetics of niobium nitride platelets in Fe

“…Precipitation in microalloyed steels is based on the combination of several metallic elements (Nb, Ti, and V) with carbon or nitrogen. Particularly, Nb is known to form carbonitrides of NaCl structure, where carbon and nitrogen substitute on the same lattice sites [1][2][3][4]. Nb-(C,N) precipitates are widely used both for grain size control at high temperature in the austenitic phase and for strengthening at lower temperature in the ferritic phase [5][6][7].…”