9–12% Cr Heat-Resistant Martensitic Steels with Increased Boron and Decreased Nitrogen Contents

Abstract

As a promising alloying approach, the modification of chemical composition by increasing the B content and decreasing the N content has been applied to improve the creep resistance of various 9–12% Cr heat-resistant martensitic steels. This paper presents an overview of the creep strength and related microstructural features of the 9% Cr and 10–12% Cr martensitic steels with high B and low N contents. The factors that determine the optimal B/N ratio in steels are considered. The creep properties are compared with those for similar steels with conventional B and N contents. The relationships between the stability of lath structure and precipitates of M23C6, Laves, and MX phases and the creep strength of steels are considered. Further perspectives of this modification of alloying by high boron and low nitrogen are outlined.

Experimental Study of the Evolution of Creep-Resistant Steel’s High-Temperature Oxidation Behavior

“…The process of standardization steel annealing influenced the distribution and nature of tempered martensite due to the nature of martensite laths as well as bainite formations of the tempered bainite. Additionally, studies [21,22] evaluated the standardization annealing process and structure of 9-11Cr martensitic steels. 2a,b exhibit the microstructure of the steel at its initial state prior to exposure to the atmospheric oxidation conditions documented by TEM.…”

“…The process of standardization steel annealing influenced the distribution and nature of tempered martensite due to the nature of martensite laths as well as bainite formations of the tempered bainite. Additionally, studies [21,22] evaluated the standardization annealing process and structure of 9-11Cr martensitic steels. Figure 2c shows the results of SAED analysis of particles present at and around the prior austenitic grain boundaries, which, according to the EDS analyses results, contained, in addition to a high C content, mostly Cr, a slightly lower Fe content, W, and in some Figure 2c shows the results of SAED analysis of particles present at and around the prior austenitic grain boundaries, which, according to the EDS analyses results, contained, in addition to a high C content, mostly Cr, a slightly lower Fe content, W, and in some cases a minor V content.…”