The Initial Precipitation Behavior of Copper in Ferritic Stainless Steel

  • PDF / 1,680,666 Bytes
  • 9 Pages / 593.972 x 792 pts Page_size
  • 96 Downloads / 210 Views

DOWNLOAD

REPORT


ASM International 1059-9495/$19.00

The Initial Precipitation Behavior of Copper in Ferritic Stainless Steel Hongxiang Yin, Yi Wu, Yao Huang, Guanzhen Zhang, Xiang Li, Pengpai Zhang, and Aimin Zhao (Submitted April 7, 2020; in revised form September 6, 2020; Accepted: 8 September 2020) The precipitation of a suitable amount of Cu phase is the key to the antibacterial performance of Cucontaining antibacterial stainless steel. In order to study the precipitation behavior of Cu in ferritic stainless steel, the nucleation rate–temperature curve and phase transition kinetics curve of the Cu-rich phase were calculated theoretically. The distribution, size, and composition of Cu precipitates were characterized, and the distributions of Ni and Mn in the Cu precipitates at different annealing times were also analyzed by atom probe tomography and transmission electron microscopy. The crystal structure of the Cu precipitates was observed by high-resolution electron microscopy. With an increase in annealing temperature, the nucleation rate decreases and the time for nucleation of Cu precipitates increases monotonously. Accordingly, the size of the Cu-rich phase increases, and the number density decreases with increasing annealing time. Moreover, the contents of Ni and Mn gradually increase, and the Ni and Mn atoms aggregate on the surface of the Cu-rich phase. When the steel is annealed for 60 s, the Cu precipitate in the ferrite matrix exhibits a 9R structure with multiple twins. Keywords

atom probe tomography, Cu precipitate, kinetic curve, ultrapure ferritic stainless steel

1. Introduction Cu-bearing antibacterial stainless steels are a novel class of materials preferred for the low cost and dual characteristics of mechanical properties and antibacterial function in recent years. These stainless steels have a wide range of prospective applications and can be used in an antibacterial environment with high hygienic requirements, such as household appliances, kitchenware, and sanitary ware (Ref 1-5). Antibacterial functionality is imparted to stainless steels by the addition of elemental Cu in a concentration that exceeds its saturation amount. It forms a Cu precipitate of a certain size when subjected to an appropriate heat treatment process, which can dissolve Cu2+ killing Escherichia coli and Staphylococcus aureus (Ref 6, 7). Therefore, the study of Cu precipitates is the basis for elucidating the antibacterial properties of Cu-bearing steel. Over the years, the understanding of the Cu precipitation process has been gradually refined with continuous advances in detection technology. The precipitation kinetics of the Cu-rich phase are the theoretical basis for studying Cu precipitation behavior. It has Hongxiang Yin and Yi Wu: Associate research fellow, mainly engaged in the development and application of metal materials. Hongxiang Yin, Yi Wu, Guanzhen Zhang, Xiang Li, and Pengpai Zhang, China Academy of Railway Sciences Corporation Limited, Beijing 100081, China; Yao Huang, China Electric Power Research Institute, Beijing

Data Loading...