Properties Of Martensitic Stainless Steel Research Articles

Microstructure and Mechanical Properties of Laser Direct Energy Deposited Martensitic Stainless Steel 410

The aim of this work is to study the phase transformations, microstructures, and mechanical properties of martensitic stainless steel (MSS) 410 deposits produced by laser powder-directed energy deposition (LP-DED) additive manufacturing. The LP-DED MSS 410 deposits underwent post-heat treatment, which included austenitizing at 980 °C for 3 h, followed by different tempering treatments at the temperatures of 250, 600, and 750 °C for 5 h, respectively. The analyses of phase transformations and microstructural evolutions of LP-DED MSS 410 were carried out using X-ray diffraction, SEM-EDS, and EBSD. Vickers hardness and tensile strength properties were also measured to analyze the effects of the different tempering heat treatments. It revealed that the as-built MSS 410 has very fine lath martensite, high hardness of about 480 HV1.0, and tensile strength of about 1280 MPa, but elongation was much lower than the post-heat-treated ones. Precipitations of chromium carbide (Cr23C6) were most commonly observed at the grain boundaries and the entire matrix at the tempering temperatures of 600 °C and 750 °C. In general, the tensile strength decreased from 1381 MPa to 688 MPa as tempering temperatures increased to 750 °C from 250 °C. Additionally, as the tempering temperature increased, the chromium carbide and tempered martensite structures became coarser.

Effect of Tempering Time on the Microstructure and Properties of Martensitic Stainless Steel

Martensitic stainless steels (MSSs) have been widely used in the manufacture of turbine blades, surgical instruments, and cutting tools because of their hardness and corrosion resistance. The MSSs are usually tempered at a temperature no higher than 250 °C after quenching to avoid the decline in the hardness, strength, and corrosion resistance of the steels. However, some short-time thermal shocks are inevitable in processes like welding, water grinding, laser marking, etc., in the manufacturing of kitchen knives, all of which may have negative effects on the mechanical properties and corrosion resistance. The effects of these short-time thermal shocks have rarely been studied. In this paper, the martensitic stainless steel 5Cr15MoV (X50CrMoV15 is European Standards) was selected to be tempered at the sensitization temperatures (480 to 600 °C) for a series of times (0.5 to 128 min) after quenching, and the microstructures, hardness, and corrosion resistance of the steel after tempering were investigated. It was shown that the variation in hardness and corrosion resistance of the 5Cr15MoV steel could be divided into four stages over time during tempering at the sensitization temperatures. The hardness of steel was found to increase at first and then decrease with time; accordingly, good corrosion resistance was retained in the initial few minutes of tempering, which then deteriorated fast. The variation in hardness and corrosion resistance of the 5Cr15MoV steel is related to the diffusion of C and Cr atoms at different tempering temperatures. The mechanism of the mechanical properties and corrosion resistance variation caused by the diffusion of C and Cr atoms during tempering at the sensitization temperatures was also discussed.

Effect of δ-ferrite on the H-trapping behavior in the martensitic stainless steel

δ-ferrite usually plays an important role in the mechanical properties of martensitic stainless steel. However, there are few studies on the effect of δ-ferrite on hydrogen embrittlement (HE) in martensitic steel. In this study, the H-trapping of δ-ferrite and the effect on the HE in martensitic stainless steel is investigated. The hydrogen distribution characteristics were observed by atomic force microscope scanning (AFM), and the related results show that the δ-ferrite, martensite and δ-ferrite/matrix (F/M) interface can act as hydrogen traps. The martensite and F/M interface has the higher hydrogen-trapping capability, hydrogen diffuses in δ-ferrite is faster than that of martensite. During deformation, Electron Back Scatter Diffraction (EBSD) observation shown that the exist of δ-ferrite can release the stress concentration caused by the poor deformation ability of martensitic grains, and further improve the resistance of HE. The results provide valuable insights into the behavior of δ-ferrite in the HE.

Investigation of laser-powder bed fusion driven controllable heterogeneous microstructure and its mechanical properties of martensitic stainless steel

Martensitic stainless steels, fabricated by laser-powder bed fusion (L-PBF) technology, have recently garnered considerable attention owing to their high strength and favorable corrosion resistance for automotive and aerospace applications. However, intricate and inhomogeneous temperature history during the L-PBF process makes it challenging to understand the microstructure evolution and the corresponding mechanical properties. This study aims to explore the potential of this technology in enhancing the mechanical properties of martensitic stainless steels. It specifically focuses on the microstructure resulting from the inherent quenching and tempering heat treatment that occurs during the process. The distinctive microstructure of AISI 410 stainless steel included alternating high-temperature tempered, coarsened grain, and low-temperature tempered zones. Consequently, the as-built stainless steel exhibited the exceptional mechanical properties: an ultimate tensile strength of 1350 ± 55 MPa and an elongation at fracture of 14.3 % ± 1.2 %. Remarkably, these mechanical properties are comparable to those of AISI 410 stainless steel treated with a conventional quenching and partitioning heat treatment. These findings support for the effectiveness of in-situ quenching and tempering during L-PBF, demonstrating its potential to yield high-performance heterogeneous alloys.

Thermal and diffusion conditions for delta ferrite formation in partially melted and heat-affected zones of multipass SAW joint performed in martensitic stainless steel 12Cr–1Mo

It is widely known the harmful delta ferrite effect on the mechanical properties of martensitic stainless steel (MSS), especially in the partially melted (PMZ) and heat-affected (HAZ) regions brought about the welding thermal cycle. Therefore, this research studied the cooling and diffusion conditions responsible for delta ferrite formation, distribution, and morphology. A finite element numerical model helped to estimate the welding thermal cycle and then was correlated with delta ferrite formation. The numerical analysis considered the application of the submerged arc welding (SAW) process in multipass mode to obtain a coupon test fabricated of MSS 12Cr–1Mo. Heat diffusion and convection processes were strongly related to ferritic phase formation in the PMZ, which affected heat dissipation. Meanwhile, solid-state diffusion of chemical species C, Cr and Mo was analyzed in the HAZ to quantify its effect on delta ferrite grains formation derived from the carbide dissolution process. There was a significant fall in mechanical strength and corrosion resistance (pitting formation) in the HAZ, where some vermicular delta ferrite chains were detected.

Microstructure and mechanical properties of a martensitic stainless steel (0.2%C–12%Cr) after quenching and partitioning (Q&P) process

This paper investigates microstructure and mechanical properties of a commercial martensitic stainless steel (0.2%C–12%Cr) after the quenching and partitioning process. The characterization was performed by optical microscopy, SEM, XRD, EBSD, density, dilatometry, hardness, Charpy, and tensile tests. Different retained austenite fractions were obtained by varying the quenching temperature (Qt). The results showed a decrease in the yield and ultimate tensile strength because of the increase in the retained austenite fraction for Qt ranging from 90 °C up to 165 °C. The absorbed energy was increased by 79%, probably due to the increment of mechanically stabilized retained austenite fraction. The fracture surface showed ductile characteristics for Qt ranging from 90 °C to 165 °C after tensile and Charpy tests. The best balance of strength and ductile found was Qt = 190 °C with a total elongation of 22.9 ± 2.2% and an ultimate tensile strength of 1444 ± 20 MPa owing to the retained austenite to martensite transformation that postponed occurrence of necking (TRIP effect). On the other hand, a decrease in the impact toughness occurred due to the retained austenite presence with low mechanical stability in the microstructure. Different fracture mechanism behavior was observed for tensile tests (ductile fracture) and impact tests (quasi-cleavage). For Qt = 215 °C, the presence of fresh martensite and non-mechanical stabilized retained austenite promoted an increase in ultimate tensile strength and a decrease in the yield strength, area reduction, total elongation, and absorbed energy. Finally, fracture surfaces showed brittle characteristics after tensile and Charpy tests.

Influence of Partitioning Effects on the Retained Austenite Content and Properties of Martensitic Stainless Steel

The effect of a quenching and partitioning (Q&P) heat treatment with a quenching temperature (TQ) range from 20 to 190 °C is investigated for two martensitic stainless tool steels X40Cr14 and “X25CrN13”, focusing on microstructural evolution, hardness, and toughness. The influence on the retained austenite (RA) content, when replacing part of carbon with nitrogen, is of core interest. The amount of RA is analyzed by X‐ray diffraction and is additionally proved with electron backscatter diffraction, and the RA content is thermodynamically calculated. Subsequently, the effect of the microstructure on toughness and hardness is investigated. For both steels, the toughness maximum is reached in the region of the RA maximum. The “X25CrN13” attains higher toughness at higher RA contents. Higher RA contents do not benefit X40Cr14. Furthermore, the effect of double tempering at higher tempering temperatures after Q&P on the steels is investigated. Besides RA contents and hardness, dilatometer curves are used to evaluate the formation of fresh martensite in the microstructure. The secondary hardness maximum of “X25CrN13” is reached at 500 °C and that of X40Cr14 is at 480 °C. For double tempering temperature at 520 °C, TQ has little effect on toughness, and “X25CrN13” shows better values.

Optimizing mechanical properties of 15Cr supermartensitic stainless steel by enhanced stability of retained austenite

The effect of annealing temperature below austenite start transformation temperature on the mechanical properties of martensitic stainless steel was investigated. The annealing treatment can transform the anisotropic compressive stress of retained austenite into hydrostatic pressure, which stabilizes the retained austenite and increases the elongation of the martensitic stainless steel.

Evaluation of thermal processing and properties of 422 martensitic stainless steel for replacement of 4140 steel in diesel engine pistons

The thermal and mechanical properties of martensitic stainless steel 422 were evaluated for suitability as a drop-in replacement for 4140 steel in next generation heavy-duty diesel engine (HDDE) pistons. The time and temperature of the austenitization and tempering steps were studied to achieve optimum materials performance in piston applications, including the balance of thermal and mechanical properties and resistance to long-term thermal aging. Reducing the tempering temperature from 700 to 600 °C caused a substantial increase in elevated temperature strength from 25 to 600 °C, but had no significant influence on thermal conductivity, suggesting that thermal conductivity in 422 is dominated largely by composition and distribution of alloying elements and mostly independent of the sub-grain structure size and precipitate size. Compared to the current HDDE piston alloy 4140, 422 exhibits substantially higher elevated temperature strength and lower thermal conductivity, the latter which will cause 422 to operate at higher temperatures in pistons, possibly requiring a piston redesign to take advantage of the improved high temperature strength of 422. Piston material selection and alloy design strategies with potential to mitigate some of the shortcomings of martensitic stainless steels, such as 422, as drop-in replacements are discussed.

Effect of Forging Deformation and Cooling on Mechanical Properties of Martensitic Stainless Steel

Stainless steel has good mechanical properties compared to other materials for strength and hardness, usually it will increase in hardness after hardening or forging. The purpose of this study was to obtain information about: The value of hardness and tensile strength of martensitic stainless steel forging with various deformations and cooling. The research method used is an experimental method, namely by forging on martensitic stainless steel with variations in deformation and cooling rate. Variations of forging deformation used are 25%, 50%, and 75%. The cooling media used are water, oil and air. The results of forgings with various cooling media were tested for tensile strength and tested for hardness using the Rockwell C (HRC) method. It was found that the higher the value of forging deformation, the higher the value of strength and hardness of martensitic stainless steel. This is because more and more martensite structures are recrystallized. In addition, it was also found that water and air cooling media gave an increase in the hardness of martensitic stainless steels. This is influenced by the cooling rate, where the higher the cooling rate, the more martensite structures formed, thus increasing the hardness value. The increase in hardness value is proportional to the increase in yield strength and tensile strength.

Influence of reversed austenite on the properties of a 13Cr4NiMo ultra‐low carbon martensitic stainless steel in different environments

AbstractIn this study, the influence of reversed austenite on the mechanical and corrosion resistance properties of 13Cr4NiMo martensitic stainless steel was investigated. The results reveal that the reversed austenite content in the sample increases with the increase of tempering times. The presence of an appropriate amount of reversed austenite not only improves the comprehensive mechanical properties of martensitic stainless steel but also reduces the susceptibility to pitting corrosion.

Effect of Tempering Temperature on Physical and Mechanical Properties of Martensitic Stainless Steel Repaired with Gtaw

One of the driving equipment to produce electricity that is widely used is gas turbines. To guarantee gas turbine can be operated according to its design and capacity, it is necessary to choose a material that is suitable for its operating conditions and working temperature. Commonly gas turbine compressor blade material is a martensitic stainless steel which has a high enough strength at the compressor working temperature. Damage that is often experienced occurs at the compressor blade and turbine blade. Gas tungsten arc welding (GTAW) build-up repair is one of the methods used to repair blades. This research was conducted to analyze the effect of tempering temperatures on martensitic stainless steel repaired with GTAW. Research was focus on mechanical properties and microstructure after repaired with GTAW and had heat treatment with various tempering temperatures. In the microstructure, all weld area of the specimens that were tempered at temperatures of 200, 500 and 600°C showed the same microstructure characteristics which consisted of a matrix of tempered martensite as well as chromium carbide. The size of tempered martensite at temperatures of 600°C is larger than 500 and 200°C. The strength and hardness of the material with a tempering temperature of 200°C is higher in value compared to tempering temperatures of 500°C and 600°C, while the toughness of the material with tempering temperature of 500°C is higher compared to 200°C and 600°C.

Mechanical Properties of Martensitic Stainless Steel (AISI420) Subjected to Conventional and Cryogenic Treatments

Martensitic Stainless Steel (AISI420) MSS are vastly used because of their properties conventional which mix good mechanical and corrosion resistance. Cryogenic up to -196°C for different soaking time and heat treatments at (1000,500,200°C) for 15 minutes is one of the ways that used to enhance mechanical properties of these steels by means transformation of retained austenite, deformation regarding martensite then carbide refinement. the result showed an increase in tensile strength of samples that were treated cryogenically and tempered at 500°C was 933 (MPa) compared to samples that just treated conventionally in austenitizing and tempering at the same temperature that was 880 (MPa). The hardness values increased considerably to 414HV and 321 HV for the specimen that tempered at 200°C and 500°C respectively, precipitation of small carbides was observed that this is responsible for the improvement in the mechanical properties of the material.

Mechanical properties of martensitic stainless steel weld/adhesive hybrid bonds

ABSTRACTHybrid weld-adhesive bonding (AB) was used as an approach to improve the mechanical properties of martensitic stainless steel resistance spot welds. The weld fusion zone in both techniques was composed of predominantly martensite and δ-ferrite. It was found that the presence of adhesive does not induce excess hardening effect in the fusion zone. It was shown that hybrid AB/resistance spot welding) i.e. weld-bonding) technique can double the peak load and energy absorption of the joints compared to those of the resistance spot welds. To obtain high performance weld-bonded joints, heat generation during welding should be controlled to produce weld bonds with large fusion zone size, but without detrimental effect on the adhesive strength.

Effect of Nitriding on Antibacterial Performance of 8Cr17 and 4Cr13 Martensitic Stainless Steel

Abstract Martensitic stainless steel is widely used for medical apparatus, but it can carry a large number of bacteria and cause a potential risk of infection because it has no antimicrobial ability. In this paper, nitriding of 4Cr13 and 8Cr17 martensitic stainless steel was conducted to improve the antibacterial activity. The surface morphology and phase constituents of nitrided 4Cr13 and 8Cr17 specimens were characterized using scanning electron microscopy and X-ray diffraction. Nitrogen concentration profiles in the cross sections of the nitrided specimens were obtained by glow discharge spectroscopy. The antibacterial properties of this nitrided layer were evaluated by a plate-counting method. The antimicrobial ratios of nitrided 4Cr13 and 8Cr17 martensite stainless steel against Staphylococcus aureus were 98.13 % and 99.22 %, respectively, after 12 h. The results showed that the formations of chromium nitride (CrN) and two iron nitrides (Fe3N and Fe4N) are of vital importance to the antibacterial properties of martensitic stainless steel.

Influences of Austenitization Parameters on Properties of Martensitic Stainless Steel in Hot Stamping

Due to high temperature and inevitable contact with air, strong oxidation and decarburization of the bare steel exist in hot stamping of ultra-high strength steels. Martensitic stainless steel could be a potential solution with its corrosion resistance and high strength. In this paper, the influences of austenitization temperature (850 to 1000 °C) and time (3 to 10 min) on final properties of 410 martensitic stainless steel were investigated, to obtain an ultra-high strength up to 1500MPa. The hot stamping of 410 steel is simulated by compression tests with a flat die. Mechanical properties of blanks after hot stamping process were detected by tensile tests. Results show that the final strength of 410 steel increases and the plasticity decreases, with the increase of austenitization temperature and time. After austenitization at 1000 °C for 5-10 min, an ultimate tensile strength up to 1500MPa is obtained with a martensite dominated microstructure.

Effect of Ce on the High Temperature Mechanical Properties of Martensitic Stainless Steel

The effects of Ce on the inclusions and the high temperature mechanical properties of 2Cr13 stainless steel were studied. The results show that the morphologies and sizes of inclusions in 2Cr13 stainless steel are changed, and Ce played a very good role of modifying inclusions. The high temperature strength of 2Cr13 stainless steel is improved obviously by Ce. In comparison with 2Cr13 stainless steel without Ce, the high temperature strength of 2Cr13 stainless steel with Ce is increased 18.18% at 1273K, respectively.

Microstructure and Mechanical Properties of Martensitic Stainless Steel 6Cr15MoVn

Martensitic stainless steel containing Cr of 12% to 18% (mass percent) are common utilized in quenching and tempering processes for knife and cutlery steel. The properties obtained in these materials are significantly influenced by matrix composition after heat treatment, especially as Cr and C content. Comprehensive considered the hardness and corrosion resistance, a new type martensitic stainless steel 6Cr15MoV has been developed. The effect of heat treatment processes on microstructure and mechanical properties of 6Cr15MoV martensitic stainless steel is emphatically researched. Thermo-Calc software has been carried out to thermodynamic calculation; OM, SEM and TEM have been carried out to microstructure observation; hardness and impact toughness test have been carried out to evaluate the mechanical properties. Results show that the equilibrium carbide in 6Cr15MoV steel is M23 C6 carbide, and the M23C6 carbides finely distributed in annealed microstructure. 6Cr15MoV martensitic stainless steel has a wider quenching temperature range, the hardness value of steel 6Cr15MoV can reach to HRC 60.8 to HRC 61. 6 when quenched at 1060 to 1100 °C. Finely distributed carbides will exist in quenched microstructure, and effectively inhabit the growth of austenite grain. With the increasing of quenching temperature, the volume fraction of undis-solved carbides will decrease. The excellent comprehensive mechanical properties can be obtained by quenched at 1060 to 1100 °C with tempered at 100 to 150 °C, and it is mainly due to the high carbon martensite and fine grain size. At these temperature ranges, the hardness will retain about HRC 59. 2 to HRC 61. 6 and the Charpy U-notch impact toughness will retain about 17. 3 to 20 J. A lot of M23C6 carbides precipitated from martensite matrix, at the same time along the boundaries of martensite lathes which leading to the decrease of impact toughness when tempered at 500 to 540 °C. The M3C precipitants also existed in the martensite matrix of test steel after tempered at 500 °C, and the mean size of M3C precipitates is bigger than that of M23C6 precipitates.

Effect of N on microstructure and mechanical properties of 16Cr5Ni1Mo martensitic stainless steel

The effect of adding N (about 0.1% in mass) to low carbon 16Cr5Ni1Mo martensitic stainless steel by adding nitride ferroalloy under argon protective atmospheric of near normal pressure on phase transformation and microstructure of steels subjected to normalizing and tempering was investigated by using dilatometer, laser scanning confocal microscopy, transmission electron microscopy and X-ray diffraction, and its consequence on mechanical properties was evaluated by tensile and impact tests. N can effectively avoid the occurrence of δ ferrite during solidification. N retards the kinetics of the formation of reversed austenite and promotes the occurrence of Cr 2N during tempering above 550 °C. The strength properties of the steel as normalized is enhanced by N alloying without much decrease in elongation and toughness due to the combined effects of N solution strengthening, suppression of δ ferrite and retained austenite. The slight influence of N addition on mechanical properties of martensitic stainless steel after tempering above 550 °C is attributed to the precipitation of coarse rod-like Cr 2N and loss of coherence. While the increase in volume fraction of retained austenite originated from reversed austenite with tempering temperature contributes to the decrease in strength properties and increase in toughness and elongation, the retransformation of reversed austenite into martensite affects these properties inversely.

Effect of Sintering and Heat Treatment Conditions on Mechanical Properties of Martensitic Stainless Steel Fabricated by MIM Process

The effects of sintering and heat treatment conditions on the mechanical properties of martensitic stainless steel fabricated by MIM process were investigated. The specimens were made by injecting the mixture of gas-atomized powders of 5 μm and 10 μm in mean particle diameter and a polymer binder into a metallic mold. The injection molded compacts were debound in air at 593 K for 7.2 ks. They were sintered in vacuum at temperatures between 1273 K and 1623 K for 7.2 ks. And the specimens were aged at various temperatures between 373 K and 873 K after vacuum hardening. The density of the as-sintered compact of 5 μm powder was higher than that of the as-sintered compact of 10 μm powder. In case of the as-sintered compact of 5 μm powder, the tensile strength corresponded to the change in density well, and the tensile strength of the compact sintered at 1373 K was 1600 MPa. On the other hand, in the case of the as-sintered compact of 10 μm powder, the tensile strength was rather lower than that of the as-sintered compact of 5 μm powder because of coarsening of the grain size. The tensile strength and elongation of the heat-treated compact of 5 μm powder were 1800 MPa and 12 %, respectively. The tensile strength and elongation of the heat-treated compact of 10 μm powder were 1680 MPa and 10 %, respectively. Thus, the mechanical properties of the compacts were approximately equal to those of the wrought material.