Effect of boron concentration on hot deformation behavior of stainless steel

The development of new lightweight materials is required for the automotive industry to reduce the impact of carbon dioxide emissions on the environment. The lightweight, high-manganese steels are the prospective alloys for this purpose. Hot deformation is one of the stages of the production of steel. Hot deformation behavior is mainly determined by chemical composition and thermomechanical parameters. In the paper, an artificial neural network (ANN) model with high accuracy was constructed to describe the high Mn steel deformation behavior in dependence on the concentration of the alloying elements (C, Mn, Si, and Al), the deformation temperature, the strain rate, and the strain. The approval compression tests of the Fe–28Mn–8Al–1C were made at temperatures of 900–1150 °C and strain rates of 0.1–10 s−1 with an application of the Gleeble 3800 thermomechanical simulator. The ANN-based model showed high accuracy, and the low average relative error of calculation for both training (5.4%) and verification (7.5%) datasets supports the high accuracy of the built model. The hot deformation effective activation energy values for predicted (401 ± 5 kJ/mol) and experimental data (385 ± 22 kJ/mol) are in satisfactory accordance, which allows applying the model for the hot deformation analysis of the high-Mn steels with different concentrations of the main alloying elements.

Section: Introductionmentioning

confidence: 99%

Prediction of True Stress at Hot Deformation of High Manganese Steel by Artificial Neural Network Modeling

Churyumov

Kazakova

2023

“…In this case, the volatilization and fluidity of glassy state B 2 O 3 may generate some pores in the matrix, which allows the rapid diffusion of O ions, resulting in poor high-temperature oxidation resistance of Fe–B alloys. Pozdniakov et al found that the steel with a high boron content was an important material for the production of spent nuclear fuel storage with little uncontrollable hot deformation behavior, in which the stainless-steel benefits from the distinct features of boron-containing steels [ 25 ].…”

Section: Introductionmentioning

confidence: 99%

Effects of Boride Orientation and Si Content on High-Temperature Oxidation Resistance of Directionally Solidified Fe–B Alloys

Guo

He²,

et al. 2022

In this work, the as-cast directionally solidified (DS) Fe–B alloys with various Si contents and different boride orientation were designed and fabricated, and the as-cast microstructures and static oxidation behaviors of the DS Fe–B alloys were investigated extensively. The as-cast microstructure of the DS Fe–B alloys consists of the well-oriented Fe2B columnar grains and α-Fe, which are strongly refined by Si addition. The oxidation interface of the scales in the DS Fe–B alloy with 3.50 wt.% Si demonstrates an obvious saw-tooth shaped structure and is embedded into the alternating distributed columnar layer structures of the DS Fe–B alloy with oriented Fe2B and α-Fe matrix, which is beneficial to improve the anti-peeling performance of the oxide film compared with lower amounts of Si addition in DS Fe–B alloys with oriented Fe2B [002] orientation parallel to the oxidation direction (i.e., oxidation diffusion direction, labeled as Fe2B// sample). In the DS Fe–B alloys with oriented Fe2B [002] orientation vertical to the oxidation direction (i.e., labeled as Fe2B⊥ sample), due to the blocking and barrier effect of laminated-structure boride, Si is mainly enriched in the lower part of the oxide film to form a dense SiO2 thin layer adhered to layered boride. As a result, the internal SiO2 thin layer plays an obstructed and shielded role in oxidation of the substrate, which hinders the further internal diffusion of oxygen ions and improves the anti-oxidation performance of the Fe2B⊥ sample, making the average anti-oxidation performance better than that of the Fe2B// sample.

“…BSS part dimensions are generally sheet or tube, so the alloys are acquired using heat deformation processing. The hot deformation characteristics of BSS by cast have been studied in a large number of papers [ 26 , 27 , 28 , 29 ], however there are only a few studies of BSS by HIP. Since the boron-containing phases, elemental distributions, etc., within the two processes differ [ 3 , 4 ], the study of the behavior of BSS by HIP during hot compression, especially Grade 304B7 according to ASTM A887, which is widely used in nuclear spent fuel racks, is essential in order to guide future research.…”

Section: Introductionmentioning

confidence: 99%

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

Pei

et al. 2021

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.