Study on the Hot Deformation Characterization of Borated Stainless Steel by Hot Isostatic Pressing

Abstract

Borated stainless steel (BSS) specimens have a boron content of 1.86 wt%, and are prepared by hot isostatic pressing (HIP) conducted at different temperatures, ranging from 1000 to 1100 °C and a constant true strain rate (0.01, 0.1, 1 and 10 s−1). These tests, with observations and microstructural analysis, have achieved the hot deformation characteristics and mechanisms of BSS. In this research, the activation energy (Q) and Zener–Hollomon parameter (Z) were contrasted against the flow curves: Q = 442.35 kJ/mol. The critical conditions associated with the initiation of dynamic recrystallization (DRX) for BSS were precisely calculated based on the function between the strain hardening rate with the flow stress: at different temperatures from 1000 to 1100 °C: the critical stresses were 146.69–254.77 MPa and the critical strains were 0.022–0.044. The facts show that the boron-containing phase of BSS prevented the onset of DRX, despite the saturated boron in the austenite initiated DRX. The microstructural analysis showed that hot deformation promoted the generation of borides, which differed from the initial microstructure of HIP. The inhomogeneous distribution of elements in the boron-containing phase was caused by hot compression.

Comparison Study of Hot Deformation Behavior and Microstructure Evolution of Rack Steels with and without Segregation

“…Therefore, considering the strong relationship between deformation mechanism and deformation conditions, it is significantly vital to understand the hot deformation behavior of segregated and nonsegregated zones for the rack steels to optimize the hot workability and rolling process. Numerous studies of the hot deformation behavior have been conducted based on flow curves and constitutive relationships in magnesium alloys, [10][11][12] stainless steels, [13][14][15] microalloyed steels, [16][17][18] and so on. However, the effect of segregation on the hot deformation behavior is rarely reported for ultraheavy steel plates.…”