Effect of Boron on Microstructure and Impact Toughness of a 10%Cr Martensitic Steel

2012 ◽  
Vol 706-709 ◽  
pp. 847-852 ◽  
Author(s):  
Nadezhda Dudova ◽  
Rustam Kaibyshev
Keyword(s):  
Impact Toughness ◽  
Prior Austenite ◽  
Martensitic Steel ◽  
Boron Segregation ◽  
Austenite Grains

It was shown that in a 10% Cr martensitic steel enriched by boron this element tends to segregate within M23C6 carbides having the film-like shape and precipitated on the boundaries of prior austenite grains (PAG), mainly. It leads to a low value of Charpy V-notch impact toughness of 6 J/cm2. These carbides are highly resistant against the spheroidizing. Only the tempering at 770°C leads to the final formation of M23C6 carbides having the equiaxed shape. Concurrently, this tempering strongly decreases boron segregation. As a result, the 10% Cr martensitic steel exhibits a high value of Charpy V-notch impact toughness of 260 J/cm2.

scholarly journals Effect of the Thermo-Mechanical Processing on the Impact Toughness of a 12% Cr Martensitic Steel with Co, Cu, W, Mo and Ta Doping

Metals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 3
Author(s):  
Alexandra Fedoseeva ◽  
Ivan Nikitin ◽  
Nadezhda Dudova ◽  
John Hald ◽  
Rustam Kaibyshev
Keyword(s):  
Impact Toughness ◽  
Prior Austenite ◽  
Hot Forging ◽  
Mechanical Processing ◽  
Δ Ferrite ◽  
Conventional Heat Treatment ◽  
Austenite Grains ◽  
The Impact ◽  
M23c6 Carbides

This paper presents the results of an experimental investigation of a 12% Cr steel where a significant increase in Charpy impact toughness and a slight decrease in ductile-brittle transition temperature (DBTT) from 70 °C to 65 °C were obtained through thermo-mechanical processing, including interim hot forging at 1050 °C with long-term annealing at 1000 °C, as compared with conventional heat treatment. At lower temperatures ranging from −20 °C to 25 °C, the value of impact toughness comprised ~40 J cm−2 in the present 12% Cr steel subjected to thermo-mechanical processing. The amount of δ-ferrite decreased to 3.8%, whereas the size of prior austenite grains did not change and comprised about 40–50 μm. The boundaries between δ-ferrite and martensitic laths were decorated by continuous chains of Cr- and W-rich carbides. M23C6 carbides also precipitated along the boundaries of prior austenite grains, packets, blocks and martensitic laths. Thermo-mechanical processing increased the mean size of M23C6 carbides and decreased their number particle densities along the lath boundaries. Moreover, the precipitation of a high number of non-equilibrium V-rich MX particles was induced by hot forging and long-term normalizing at 1000 °C for 24 h.

AFM Study of Microstructure Role in the Cyclic Plasticity of Martensitic Steel

2016 ◽  
Vol 258 ◽  
pp. 444-447
Author(s):  
Gulzar Seidametova ◽  
Jean Bernard Vogt ◽  
Ingrid Proriol Serre
Keyword(s):  
Surface Relief ◽  
Prior Austenite ◽  
Martensitic Steel ◽  
Low Cycle Fatigue ◽  
Strain Range ◽  
Cyclic Plasticity ◽  
Cycle Fatigue ◽  
Fatigue Cycle ◽  
Total Strain Range ◽  
Austenite Grains

The paper presents the description of FSMs (fatigue slip markings) and the evaluation of cyclic plasticity markings of a 12%Cr martensitic steel by AFM surface analyses. The microstructure of a 12%Cr martensitic steel, quenched and tempered in air, consists of prior austenite grains, packets, blocks, and laths. The low cycle fatigue (LCF) test at a total strain range Δεt=1.2% was interrupted at different life fractions for the surface relief investigation by AFM. The localization of FSMs relatively to the different microstructural interfaces of the studied steel was proposed. The principal FSMs, appeared in the first fatigue cycle, are likely to be localized at the packet and block boundaries, while the secondary one (appeared later at 44% of lifetime) are at the lath boundaries or in the laths. The height of principal and secondary FSMs increases constantly during LCF cycling.

Image Evaluation of Distribution of Carbide Particles in Repeatedly Quenched (Two and Three Times) JIS-SUJ2 Steels

2021 ◽  
Vol 315 ◽  
pp. 66-71
Author(s):  
Koshiro Mizobe ◽  
Takahiro Matsueda ◽  
Yoshinobu Miyabe ◽  
Katsuyuki Kida
Keyword(s):  
Prior Austenite ◽  
Optimal Distribution ◽  
Image Evaluation ◽  
Austenite Grains ◽  
Carbide Particles

In order to investigate the relation between prior austenite grains (PAG) and the carbide particles, we observed etched microstructure in JIS-SUJ2 steel. We traced and drew the outlines of carbide particles and analyzed some of their shape values. We confirmed that the repeated quenching can refine PAG size while keeping the optimal distribution of the carbide particles.

scholarly journals Exploring the Difference in Bainite Transformation with Varying the Prior Austenite Grain Size in Low Carbon Steel

Metals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 988 ◽  
Author(s):  
Liangyun Lan ◽  
Zhiyuan Chang ◽  
Penghui Fan
Keyword(s):  
Grain Size ◽  
Prior Austenite ◽  
Low Carbon Steel ◽  
Low Carbon ◽  
Bainite Transformation ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Austenite Grains ◽  
Prior Austenite Grain Size ◽  
Prior Austenite Grain

The simulation welding thermal cycle technique was employed to generate different sizes of prior austenite grains. Dilatometry tests, in situ laser scanning confocal microscopy, and transmission electron microscopy were used to investigate the role of prior austenite grain size on bainite transformation in low carbon steel. The bainite start transformation (Bs) temperature was reduced by fine austenite grains (lowered by about 30 °C under the experimental conditions). Through careful microstructural observation, it can be found that, besides the Hall–Petch strengthening effect, the carbon segregation at the fine austenite grain boundaries is probably another factor that decreases the Bs temperature as a result of the increase in interfacial energy of nucleation. At the early stage of the transformation, the bainite laths nucleate near to the grain boundaries and grow in a “side-by-side” mode in fine austenite grains, whereas in coarse austenite grains, the sympathetic nucleation at the broad side of the pre-existing laths causes the distribution of bainitic ferrite packets to be interlocked.

scholarly journals Surface Strengthening of High-Alloyed Martensitic Steel by Staged Nitriding

2021 ◽  
Vol 346 ◽  
pp. 02035
Author(s):  
Petr Bibikov ◽  
Larisa Petrova ◽  
Irina Belashova ◽  
Peter Demin
Keyword(s):  
Phase Composition ◽  
Impact Toughness ◽  
Final Stage ◽  
Martensitic Steel ◽  
Surface Strengthening ◽  
Gas Nitriding ◽  
Diffusion Layers

Gas nitriding processes with cyclical rotation of ammonia and ammonia/air atmospheres are suggested for surface strengthening of martensitic Cr-Ni-W-Mo-V steel. One-, two-, and three-staged processes were studied differing by gas atmospheres at the final stage of processes. Microstructure and phase composition of received diffusion layers were examined. Results of microhardness, wear and impact toughness tests are discussed in correspondence with the layers structure.

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