Boron addition to AISI A213/P91 steel: Preliminary investigation on microstructural evolution and microhardness at simulated heat‐affected zone

Abstract

The motivation behind present investigation has been a step to create preliminary understanding towards structure‐property correlation i. e., microstructure and microhardness in presence of boron in P91 steel and in its subzones of heat‐affected zone with Gleeble simulation. For microstructure characterization and its comparison amongst selected two steels, light microscopy for prior austenite grain size, morphology of prior austenite grain boundaries and scanning electron microscopy at low‐resolution and high‐resolution in order to study evolution of sub‐structure i. e. martensitic lath block structure and nano‐precipitates were employed. Electron backscatter diffraction measurements of all coupons were done to understand the distribution and contribution of relative fraction of various grain and sub‐grain boundaries within local microstructure. Main effects of addition of 100 ppm boron to standard P91 steel as observed from present microstructural evaluation are; existence of fine nano‐precipitates P91‐coarse grained heat affected zone than its P91B counterpart, grain refinement in fine‐grained heat‐affected zone of both steels with partial dissolution of nano‐precipitates, coarsened nano‐precipitates in P91‐fine‐grained heat‐affected zone after post weld heat treatment, mixed‐structure of partially transformed martensite and coarsened undissolved prior austenite grains with nano‐precipitates in P91‐inter‐critical heat‐affected zone than P91B‐inter‐critical heat‐affected zone. However, difference in microhardness was primarily owing to variation of nano‐precipitates fraction area. In addition, present work induced grounds for microstructure stability i. e., grain boundary hardening in P91B weldments that suppresses type IV failure.

A Novel Heat Treatment Strategy Based on Quenching and Carbides Preprecipitation and Subsequent Critical Quenching to Improve the Thermal Fatigue Performance of AISI H13 Tool Steel

“…This is consistent with the results in Figure 3, and it is shown that the martensite lath after QPQ treatment is finer than the CQ treatment. Khajuria et al [ 21 ] have pointed out that the prior austenite grain boundaries (PAGB) and lath grain boundaries are decorated with fine M 23 C 6 in different morphologies and sizes during tempering of P91 steel. According to the obtained results of Li et al, [ 22 ] the type of the precipitated carbides has been determined as M 23 C 6 during tempering, and the type of precipitated carbide are not changed after deep cryogenic treatment.…”

Resistance spot weldability of Fe‐15.4Mn‐2.1Al‐1.2C twinning induced plasticity steel

“…Inverse pole figures are important tools to visualize the grain orientations [25]. Partially melted and recrystallised grains in partially melted zone is generally oriented through [1 0 0] direction, Figure 13d.…”

Abnormal grain growth under solution-aging treatments enables convergence mechanical properties of a Fe-Ni-Cr based austenitic alloy

“…The EBSD maps present the grain boundaries of each sample are shown in Supplementary figure. S1, where the misorientation angle of the grain boundaries are highlighted in green (less than 20°), red (20°~50°) and dark (more than 50°), respectively [24]. It is interesting to note that, for the samples under 980 °C solution treatment, grains continued to grow during the low-temperature aging treatments.…”