Martensitic stainless steel (MSS) coatings with different vanadium (V) contents (0-1.0 wt%) by microalloying have been successfully fabricated utilizing a unique laser cladding technique. The microstructure and properties of the resulting MSS coatings, with and without element V addition, have been carefully investigated by various advanced techniques, including XRD, SEM, TEM, microhardness tester, universal material testing machine, and electrochemical workstation. It was found that the V-free coating was mainly composed of martensite (M) and ferrite (F), trace M23C6 and M2N, while the V-bearing coatings consisted of M, F, M23C6, and VN nano-precipitates, and their number density increased with the increase of V content. The V microalloying can produce a significant impact on the mechanical properties of the resulting MSS laser-cladded specimens. As the V content increased, the elongation of the specimen increased, while the tensile strength and microhardness increased firstly and then decreased. Specifically, the striking comprehensive performance can be optimized by microalloying 0.5 wt% V in the MSS coating, with microhardness, tensile strength, yield strength, and elongation of 500.1 HV, 1756 MPa, 1375 MPa, and 11.9%, respectively. However, the corrosion resistance of the specimens decreased successively with increasing V content. The microstructure mechanisms accounting for the property changes have been discussed in detail.

https://www.mdpi.com/1996-1944/13/4/826/pdf

Influence of Vanadium Microalloying on Microstructure and Property of Laser-Cladded Martensitic Stainless Steel Coating

The present work focuses on the modeling and analysis of mechanical properties of structural steel. The effect of major alloying elements namely carbon, manganese and silicon has been investigated on mechanical properties of structural steel. Design of experiments is used to develop linear models for the responses namely Yield strength, Ultimate tensile strength and Elongation. The experiments have been conducted as per the full factorial design where all process variables are set at two levels. The main effect plots showed that the alloying elements Manganese and Silicon have positive contribution on Ultimate tensile strength and Yield strength. However, Carbon and Manganese showed more contribution as compared to Silicon. All three alloying elements are found to have negative contribution towards the response- Elongation. The present work is found to be useful to control the mechanical properties of structural steel by varying the major alloying elements. Minitab software has been used for statistical analysis. The linear regression models have been tested for the statistical adequacy by utilizing ANOVA and statistical significance test. Further, the prediction capability of the developed models is tested with the help of test cases. It is found that all linear regression models are found to be statistically adequate with good prediction capability. The work is useful to foundrymen to choose alloying elements composition to get desirable mechanical properties.

http://www.afe.polsl.pl/index.php/pl/4212/modeling-and-analysis-of-mechanical-properties-in-structural-steel-doe-approach.pdf

Modeling and Analysis of Mechanical Properties in Structural Steel-DOE Approach

The enhanced refinement of Cr23C6 by heterogeneous nucleation in annealed nitrogen-alloyed 4Cr5Mo2V die steel was investigated. The refinement was ascribed to the increase of undissolved V(C,N) that served as the nucleation of Cr23C6. A three-step reaction (M3C → M7C3 → M23C6) was assumed to explain the nucleation process of Cr23C6. The possibility of nucleation of M3C on V(C,N) was validated by classical nucleation theory, and the crystallographic relationship was accurately described using the Turnbull-Vonnegut disregistry.

Enhanced Refinement of Cr 23 C 6 by Heterogeneous Nucleation in Annealed Nitrogen-Alloyed 4Cr5Mo2V Die Steel

The Fe−N−V (Iron-Nitrogen-Vanadium) system

To obtain the best combination of strength and toughness due to grain refining and controlled precipitation hardening with particles of carbonitride phase, controlled rolling is carried out in the lower range of the austenite region, followed by cooling at a certain rate. This treatment can be called high-temperature thermomechanical treatment for low-alloy steels. The effect of thermomechanical treatment (controlled rolling) increases as the initial and final rolling temperatures are lowered and the degree of deformation in the last passes is increased, and also with the addition of elements that inhibit the recrystallization of austenite (Nb, V, Ti).

Structure and properties of low-alloy steels after controlled rolling

1.

Electron microscopic and phase analysis were used to determine the solubility of pure vanadium and niobium nitrides in iron. The solubility of these phases is less than 0.05 wt. % at low temperatures but increases sharply with the temperature above 700°, reaching ∼0.1% for niobium nitride and 0.2% for vanadium nitride at temperatures around 1350°.




2.

Electron microscopic analysis is a more sensitive method than phase analysis for determining the solubility of nitrides.

Solubility of vanadium and niobium nitrides in iron

Aging of Fe--VN and Fe--NbN alloys

1.

In terms of increasing stability of austenite the steels investigated can be arranged in the following order: 08G2S; 08G2S+0.03% V; 08G2S+0.05% Nb; 08G2S+0.02% Nb+0.03% V.




2.

The increase in the strength of steels 08G2S, 08G2SB, and 08G2SF and the increase of their cold resistance when the final rolling temperature is lowered to 700° are due to refining of the grains and the substructure and also to slowing down of ferrite recrystallization. Raising the final rolling temperature leads to a coarser substructure and intensive recrystallization.




3.

The increase in the strength of 08G2S steels microalloyed with vanadium or niobium is higher than for the unalloyed steel due to the precipitation of carbonitrides of these elements. Niobium is more effective in this respect.




4.

The notch toughness is highest for 08G2S steel with carbonitride hardening after final rolling at a temperature in the upper range of the austenite region.

Structure and properties of low-pearlite steel

1.

The strength of steel 03G4N2MAF increases significantly as its carbon content increases from 0.05 to 0.10–0.12% with retention of plasticity and resilience at a sufficiently high level. A further increase in carbon content is not rational, since the resilience of the steel decreases sharply with an insignificant increase in yield point.




2.

The resilience and resistance to brittle failure of the steel may improve considerably with the use of controlled rolling when its carbon content does not exceed 0.12%.

N. I. Karchevskaya

Papers

Solubility of vanadium and niobium nitrides in iron

Aging of Fe--VN and Fe--NbN alloys

Structure and properties of low-pearlite steel

Effect of carbon content on the structure and mechanical properties of high-strength weldable steel 03G4N2MAF

The first draft laws of the State Duma of the Russian Empire