440C Martensitic Stainless Steel Research Articles

Behavior of Retained Austenite and Carbide Phases in AISI 440C Martensitic Stainless Steel under Cavitation

In this work emphasis was given to determine the evolution of the retained austenite phase fraction via X-ray diffractometry technique in the as-hardened AISI 440C martensitic stainless steel surface subjected to cavitation for increasing test times. Scanning electron microscopy results confirmed the preferential carbide phase removal along the prior/parent austenite grain boundaries for the first cavitation test times on the polished sample surface during the incubation period. Results suggest that the strain-induced martensitic transformation of the retained austenite would be assisted by the elastic deformation and intermittent relaxation action of the harder martensitic matrix on the austenite crystals through the interfaces between both phases. In addition, an estimation of the stacking fault energy value on the order of 15 mJ m−2 for the retained austenite phase made it possible to infer that mechanical twinning and strain-induced martensite formation mechanisms could be effectively presented in the studied case. Finally, incubation period, maximum erosion rate, and erosion resistance on the order of 7.0 h, 0.30 mg h−1, and 4.8 h μm−1, respectively, were determined for the as-hardened AISI 440C MSS samples investigated here.

The Effect of Cryogenic Treatment Temperature on the Mechanical Properties and Microstructure of 440C Martensitic Stainless Steel

The Effect of Cryogenic Treatment Temperature on the Mechanical Properties and Microstructure of 440C Martensitic Stainless Steel

Effect of Heat Treatment Processes on the Microstructure and Mechanical Properties of Spray‐Formed 440C Martensitic Stainless Steel

Herein, 440C martensitic stainless steel (440C MSS) is manufactured by spray forming (SF) technology. Microstructural and mechanical properties such as strength, ductility, and toughness are evaluated after quenching and tempering–partitioning (Q–TP) and quenching–intercritical–quenching–tempering (Q–IQ–T) heat treatments. The microstructural features that control the deformation and fracture behavior of the heat‐treated specimens are discussed. The experimental results show that after austenitizing at 1050 °C, the material exhibits no apparent plastic deformation before fracture. However, specimens austenitized above 1050 °C and the specimen subjected to Q–IQ–T exhibit an improvement in the tensile properties by showing an elastic–plastic transition that is related to the strain‐induced martensitic transformation of retained austenite formed during the Q–TP process and to a decrease in the volume fraction of martensite with increasing austenitizing temperature. Also, it is observed that the strain hardening rate decreases with increasing austenitizing temperature. Furthermore, the stress–strain data suggest that the Q–IQ–T heat treatment effectively improves the toughness and ductility of the steel without compromising strength. The results indicate that the mechanical response of the SF‐440C MSS can be tailored by adjusting the heat treatment parameters to enable better design for industrial applications.

CRUCIBLE 154 CM

Abstract Crucible 154 CM is a modification of 440C martensitic stainless steel to which molybdenum has been added. Crucible 154 CM has better corrosion resistance, better wear resistance, and better hot-hardness than 440C. For knifemakers, it offers better edge retention than 440C. It also has higher attainable hardness and better through hardening characteristics than 440C. This datasheet provides information on composition, physical properties, hardness, and elasticity. It also includes information on corrosion resistance and wear resistance as well as heat treating and machining. Filing Code: TS-831. Producer or source: Crucible Industries LLC.

CARTECH MICRO-MELT 440-XH

Abstract CarTech Micro-Melt 440-XH is an air-hardening, high-carbon, high chromium, corrosion resistant alloy tool steel that is produced by the powder metallurgy process. It can be considered as either a high hardness Type 440C martensitic stainless steel or a corrosion- resistant Type D2 alloy tool steel. CarTech Micro-Melt 440-XH possesses corrosion resistance equivalent to that of Type 440C martensitic stainless steel and can attain a maximum hardness of 64 HRC. In addition, the composition of CarTech Micro-Melt 440-XH has been balanced so that it can attain a minimum hardness of 60 HRC when air cooled from the hardening temperature. This datasheet provides information on composition, physical properties, hardness, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, and machining. Filing Code: TS-819. Producer or source: Carpenter Technology Corporation.

Experimental investigation on the performance of AISI 440C martensitic stainless steel against the formation of white etching areas under sliding dynamic loading

ABSTRACT Bearings fail prematurely in transient operating conditions, as a result of flaking that causes changes in subsurface microstructure. In this type of failure, the formation of White Etching Cracks (WECs) is preceded by the formation of White Etching Areas (WEAs). Typically the WEAs are formed due to the dissolution of cementite into the matrix in AISI 52100 bearing steel. This feasibility work investigates the performance of AISI 440C steel against WEAs formation using dynamic load Pin-on-Disc tribometer. Experiments were performed at 4.5 Hz loading frequency, Hertzian pressure 2.02 GPa and sliding velocity of 0.2 ms-1 under the boundary lubrication using Poly Alpha Olefins (PAO). From post-test analysis, it is found that AISI 440C steel trapped more hydrogen than AISI 52100 bearing steel. The comprehensive analysis of materials and lubricants revealed that the performance of AISI 440C stainless steel against WEAs formation is better than that of AISI 52100 bearing steel.

Failure analysis of AISI 440C strand dies used in twin screw extruders during polymer compounding

In view of excellent wear and corrosion resistance, AISI 440C Martensitic Stainless steel finds wide use as Dies in Twin Screw Extruders in Polymer, Food and Pharma applications, especially when either additives, which could be corrosive, are added to aid compounding of polymers or moisture and/or free radicals are present in the processing material. Two AISI 440C Die Plates part of Strand Die Assembly in a φ40 mm size Twin Screw Extruder abruptly cracked during operation in succession disrupting regular production with the second failure occurring after about two years of the Extruder in service. While visual examination of the failed Die Plates showed presence of surface / sub-surface cracks and marks of corrosion, the sectioned Die Plate revealed multiple internal cracks. The hardness survey on the failed Die Plates confirmed values between 30 and 36 HRC, which are about 20–25 HRC lower than the hardness measured in as-supplied condition. Macro-examination of the sectioned Die Plate revealed multiple micro-crack origin locations together with strong evidence of corrosion. The microstructural examination showed carbide network along grain boundaries in a matrix consisting of tempered martensite and revealed intergranular fracture. Fractographic observations using Scanning Electron Microscopy on the cracked Die Plate clearly revealed segregation of fine carbides along crack boundaries. Based on detailed analyses, which included site data collection and investigation, the failure of Die Plates was attributed to Stress Corrosion Cracking. Finally, recommendations were proposed to prevent recurrence of such failures in service.

Effect of Heat Treatment on Microstructure, Mechanical Property and Corrosion Behavior of STS 440C Martensitic Stainless Steel

Martensitic stainless steel is commonly used in the medical implant instrument. The alloy has drawbacks in terms of strength and wear properties when applied to instruments with sharp parts. 440C STS alloy, with improved durability, is an alternative to replace 420 J2 STS. In the present study, the carbide precipitation, and mechanical and corrosion properties of STS 440C alloy are studied as a function of different heat treatments. The STS 440C alloy is first austenitized at different temperatures; this is immediately followed by oil quenching and sub-zero treatment. After sub-zero treatment, the alloy is tempered at low temperatures. The microstructures of the heat treated STS 440C alloy consist of martensite and retained austenite and carbides. Using EDX and SADP with a TEM, the precipitated carbides are identified as a Cr23C6 carbide with a size of 1 to 2 μm. The hardness of STS 440C alloy is improved by austenitization at 1,100 oC with sub-zero treatment and tempering at 200 oC. The values of Ecorr and Icorr for STS 440C increase with austenitization temperature. Results can be explained by the dissolution of Cr-carbide and the increase in the retained austenite. Sub-zero treatment followed by tempering shows a little difference in the properties of potentiodynamic polarizations.

Microstructure and mechanical properties of low temperature carburizing layer on AISI 440C martensitic stainless steel

In this study, the microstructure and mechanical properties of AISI 440C martensitic stainless steel with low temperature carburizing (LTC) layers were investigated by microscopes, X-ray diffraction (XRD), Vickers indenter and pin-on-disc test device, etc. LTC treatment was conducted at 420 °C for 10–40 h on the quenched-tempered steel samples by pack method. Results indicated that the LTC layers formed on base metal exhibited compact and regular morphology, and carbon-expanded martensite (α′c), Fe3C and Cr23C6 compounds were examined in the LTC layers by XRD analysis. Besides, the layer hardness from 1430 to 1720 HV0.025 with processing time increased, which was approximately three times higher than that of the specimen without LTC treatment. However, as the processing time increased, the adhesion strength of LTC layers deteriorated and the indentation grade decreased from HF1 to HF3. In addition, the wear resistance was significantly improved after the LTC treatment, and the wear rate of the LTC layer decreased by 93.7% in comparison with the untreated condition.

Effect of Partial Solution Treatment Temperature on Microstructure and Tensile Properties of 440C Martensitic Stainless Steel

The 440C martensitic stainless steel is considered to be among the hardest steels, owing to its high carbon content. Careful heat treatment of this material introduces multiple carbide particles, which can alter microstructure and mechanical properties. This study focused on the effect of austenitisation temperature on the microstructure and tensile properties of 440C steel. Austenitisation was performed on the austenite + carbide region, because 440C steel lacks a single-phase region. The steel was austenitised at two different temperatures; namely, 1160 °C and 950 °C, and subjected to oil quenching. The as-quenched samples showed a typical lath martensite structure with retained austenite phase. The treatments at 1160 °C and 950 °C promoted the formation of M7C3 and M23C6 carbides, respectively. The austenite grains in the sample treated at 1160 °C showed a higher growth rate than those in the sample treated at 950 °C. The sample treated at 1160 °C showed low-fraction and a large-size carbide phase. The Zener pinning force decreased, thereby increasing the austenite grain growth in the sample treated at 1160 °C. The hardness and 0.2% proof stress of the sample treated at 950 °C were higher than those of the sample treated at 1160 °C, owing to the higher martensite content in the former. The strength–ductility balance of the sample treated at 950 °C was higher than that of the sample treated at 1160 °C. The decreased austenitisation temperature resulted in improved mechanical properties of the steel. Therefore, the austenitisation temperature alters the microstructure and mechanical properties of 440C steel.

Effects of Ni and Cr addition on the wear performance of NiTi alloy

Development of hard materials for structural and bearing applications is a challenging task due to complexities in materials processing. Nickel-based intermetallics are a choice for the wear resistance applications. In this study, in order to examine the effects of Ni and Cr addition on the wear performance of Ni-rich alloys, 60Ni, 55Ni-5Cr, 50Ni-5Cr, and 50Ni-10Cr (at.%) alloys were developed through arc melting technique. The aim was to conduct a microstructural and phase analysis study and their effects on hardness and wear behavior. Samples were solution treated at 900 °C for 5 h under vacuum followed by equilibrium cooling. Microstructural and phase analysis revealed the presence of B2 cubic NiTi austenite along with Ni-rich hexagonal Ni3Ti and Cr-rich tetragonal Cr3Ni2 phases throughout the microstructure of alloys. The Cr developed phase was not present in binary composition because of Cr absence. Ternary compositions possessed higher hardness and wear resistance than the binary alloy. Hardness and wear resistance of 50Ni-5Cr and 50Ni-10Cr were comparable with tool steels and conventional 440C martensitic stainless steel bearing material; this high hardness and wear resistance was attributed to the strong solid solution strengthening and precipitation hardening effects of Cr along with the combined effect of Ni-rich Ni3Ti and NiTi austenite phases. Improvement in hardness and wear resistance were correlated with the Cr addition in the developed alloys.

Effect of Deposition Time on Properties of ZrO<sub>2</sub> Coating Prepared Using Electrolytic Method

AISI 440C martensitic stainless steel is one of the most widely studied engineering materials for its tribological properties. It is capable of attaining the best mechanical properties such as high strength and hardness compared to other martensitic grades. Unfortunately, the corrosion resistance of this 440C steel is the lowest among the stainless group, which results in the precipitation of carbide phases. AISI 440C were coated using electrolytic ZrO2 layer deposition method in ZrO(NO3)2 aqueous solution. In order to preserve the high mechanical properties of this steel, various heat treatment processes applied to the coated samples. After drying and annealing, the ZrO2 coated samples were evaluated using SEM, hardness tests and corrosion tests. Some mud-crack had been indicated in all samples. However, it become more homogeneously on the sample which undergoes longer deposition time. This difference resulted in a significant improved on corrosion resistance of ZrO2 coated sample.

Microstructure and Properties of Heat-Treated 440C Martensitic Stainless Steel

440C martensitic stainless steels are widely used because of their good mechanical properties. The mechanical properties of 440C martensitic stainless steel were evaluated after heat treatment of these materials at various types of heat treatment processes. The initial part of this investigation focused on the microstructures of these 440C steels. Microstructure evaluations from the as-received to the as-tempered condition were described. In the as-received condition, the formations of ferrite matrix and carbide particles were observed in this steel. In contrast, the precipitation of M7C3 carbides and martensitic structures were present in this steel due to the rapid quenching process from the high temperature condition. After precipitation heat treatment, the Cr-rich M23C6 carbides were identified within the structures. Moreover, a 30 minutes heat-treated sample shows the highest value of hardness compared to the others holding time. Finally, the tempering process had been carried out to complete the whole heat treatment process in addition to construct the secondary hardening phenomenon. It is believed that this phenomenon influenced the value of hardness of the 440C steel.

Corrosion and wear of zinc in various aqueous based environments

The corrosion and corrosive wear resistance of zinc sliding against 440C martensitic stainless steel counterface, were studied in aqueous based solutions having different NaCl and sodium molybdate dihydrate concentrations respectively. The main objective was to investigate the effect of aqueous based environments and corrosion inhibitors on the interface and tribological characteristics of this tribosystem, as in several cases the formation of a thin corrosion product layer can act as a lubricating film. The experimental results indicated that sodium molybdate dihydrate acted as a corrosion inhibitor, decreasing significantly the corrosion susceptibility of zinc. However, during the corrosive wear of zinc under free corrosion conditions, the addition of sodium molybdate dihydrate inhibitor did not improve the tribological properties of zinc, as higher friction coefficients of the tribosystem were recorded. This observation indicates that aqueous lubrication cannot be applied in this tribosystem, even though an inhibitor was used to minimize the effect of Cl− halide ions. In addition, the observed wear mechanisms of zinc were mainly plastic deformation and abrasion. These wear mechanisms coexisted with pitting and dissolution–precipitation corrosion phenomena on the surface of this material.

Microstructures and properties of friction surfaced coatings in AISI 440C martensitic stainless steel

While martensitic stainless steel AISI 440C is an attractive material for wear protection in many industrial applications, it is difficult to realize satisfactory coatings in this material using conventional weld overlay processes. Friction surfacing, a promising solid-state process, can help in this regard. In the current study, alloy 440C coatings were successfully made on low carbon steel substrates using friction surfacing. Bend and shear tests on coated specimens indicated excellent coating/substrate bonding. Microstructures, corrosion behavior, and wear performance of these coatings were compared with standard heat treated alloy 440C bulk material. While friction surfaced coatings in alloy 440C exhibited superior corrosion resistance to standard heat treated alloy 440C bulk material, their wear resistance was found to be somewhat inferior. Apart from these studies, experiments were conducted to assess the potential of the process for wide area coverage. Studies show that it is possible to achieve well-bonded coatings consisting of multiple overlapping tracks with excellent inter-track bonding. Overall, the current study demonstrates that friction surfacing is a very useful process for producing wear resistant coatings in difficult-to-fusion-deposit materials such as alloy 440C martensitic stainless steel.

Microstructural Characterization of ZrO<sub>2</sub> Layer Coating on Martensitic Stainless Steel

High carbon steel stainless steel such as 440C martensitic stainless steel, are commonly used for automotive components, such as ball bearings, races, gage blocks and valve. In this study, 440C steel was coated with ZrO2 by electrolytic deposition in ZrO(NO3)2 aqueous solution. After annealing, the ZrO2 coated specimens were characterized by x-ray diffraction (XRD) and scanning electron microscope (SEM). Scanning electron micrograph showed that thickness of the coated sample was approximately 0.7µm. Besides that, secondary hardening effect occurred on the annealed SS440C substrate and it might be due to the presence of secondary carbide.

Microstructure and sliding wear resistance of an Al–12 wt.% Si/TiC laser clad coating

Metal matrix composite coatings consisting of an Al–12wt.% Si-alloy matrix reinforced with TiC were prepared by laser cladding from mixtures of Al–12wt.% Si alloy and TiC powders. For the processing parameters used (power density 200MW/m2 and interaction time 0.3s), a small proportion of TiC dissolves in the melt, resulting in a microstructure composed of 34vol.% of TiC and 3vol.% of Ti3SiC2 particles dispersed in a matrix consisting of proeutectic α-Al dendrites and α-Al+Si eutectic. The coating material presents a hardness of 165HV and a wear coefficient of 2.24×10−5mm3/(Nm) in ball-on-plate dry sliding wear tests, using quenched and tempered AISI 440C martensitic stainless steel as the counterbody material. Analysis of the worn surfaces showed that the sliding motion of the contacting bodies leads to the formation of a tribolayer consisting of Fe oxides, as well as metallic phases. On the basis of theoretical calculations it is suggested that the primary material removal mechanism involves the propagation of cracks through the thickness of this tribolayer, followed by crack channeling and debonding of tribolayer fragments.

Performance of CBN and PCBN Tools on the Machining of Hard AISI 440C Martensitic Stainless Steel

In this study, flank wear on CBN and PCBN tools due to cutting forces were studied. Turning tests were carried using cutting speeds of 100, 125, 150, 175 and 200 m/min with feed rates of 0.10, 0.20 and 0.30 mm/rev and constant depth of cut. The performances of tools were evaluated based on the flank wear and cutting forces. There is clear relationship between flank wear and cutting forces while turning hard martensitic stainless steel by CBN and PCBN tools. Low cutting forces leads to low flank wear formation and low cutting forces provided good dimensional accuracy of the work material including low surface roughness. Flank wear formation was mostly caused by abrasion and adhesion. The built up edges formed reduced the cutting forces and also causes the heat generated at tool tip and work interface. High cutting forces are identified and this may be due to heat and flank wear combinations. Flank and crater wear on the rake face and hard metal deposition due to diffusion of metals on the cutting tool surface are the damages occurred during process.

Tribological behavior of hafnium diboride thin films

Transition metal diborides and their coatings offer an excellent combination of high hardness, high chemical stability and high thermal conductivity, thus they are excellent candidates for a wide range of tribological applications. In this work, stoichiometric hafnium diboride films were grown by chemical vapor deposition from a single-source, heteroatom-free precursor Hf(BH 4) 4 under conditions that afford highly conformal and smooth films. HfB 2 films of thickness ∼ 0.6 μm deposited on steel substrates were subjected to pin-on-disk wear testing against a counter face disc of AISI 440C martensitic stainless steel. Based on wear measurements, both as-deposited (X-ray amorphous) and annealed (nanocrystalline) samples showed very high wear resistance compared to uncoated samples. For the annealed samples, SEM analysis indicated the formation of a wear resistant composite body in the wear scar, even at depths far exceeding the film thickness, which appears to dramatically improve wear resistance. No mild-to-severe wear transition was observed which indicates that mild wear occurred throughout the wear test. This ensemble of results, when considered in the light of high contact pressures (∼ 700 MPa) used in the study, makes the HfB 2 material potentially attractive for wear-resistant applications.

Effects of laser treatments on cavitation erosion and corrosion of AISI 440C martensitic stainless steel

Laser surface treatments with high and low fluence were employed to induce melting and transformation hardening on 440C. While melting could bring about better improvement in corrosion resistance, transformation hardening was more effective in enhancing the cavitation erosion resistance. Compared with conventional heat treatment, laser treatments resulted in higher corrosion resistance with a wide passive range in NaCl solution, and also in higher cavitation erosion resistance in both deionized water and NaCl solution.