Low Alloy Wear Resistant Steel Research Articles

The Strengthening Role of Cryogenic Treatment in the Mechanical Properties and Abrasive Wear of Low Alloy Wear-Resistant Steel

The Strengthening Role of Cryogenic Treatment in the Mechanical Properties and Abrasive Wear of Low Alloy Wear-Resistant Steel

Effect of Mo and Cr on the Microstructure and Properties of Low-Alloy Wear-Resistant Steels.

Low-alloy wear-resistant steel often requires the addition of trace alloy elements to enhance its performance while also considering the cost-effectiveness of production. In order to comparatively analyze the strengthening mechanisms of Mo and Cr elements and further explore economically feasible production processes, we designed two types of low-alloy wear-resistant steels, based on C-Mn series wear-resistant steels, with individually added Mo and Cr elements, comparing and investigating the roles of the alloying elements Mo and Cr in low-alloy wear-resistant steels. Utilizing JMatPro software to calculate Continuous Cooling Transformation (CCT) curves, conducting thermal simulation quenching experiments using a Gleeble-3800 thermal simulator, and employing equipment such as a metallographic microscope, transmission electron microscope, and tensile testing machine, this study comparatively investigated the influence of Mo and Cr on the microstructural transformation and mechanical properties of low-alloy wear-resistant steels under different cooling rates. The results indicate that the addition of the Mo element in low-alloy wear-resistant steel can effectively suppress the transformation of ferrite and pearlite, reduce the martensitic transformation temperature, and lower the critical cooling rate for complete martensitic transformation, thereby promoting martensitic transformation. Adding Cr elements can reduce the austenite transformation zone, decrease the rate of austenite formation, and promote the occurrence of low-temperature phase transformation. Additionally, Mo has a better effect on improving the toughness of low-temperature impact, and Cr has a more significant improvement in strength and hardness. The critical cooling rates of C-Mn-Mo steel and C-Mn-Cr steel for complete martensitic transition are 13 °C/s and 24 °C/s, respectively. With the increase in the cooling rate, the martensitic tissues of the two experimental steels gradually refined, and the characteristics of the slats gradually appeared. In comparison, the C-Mn-Mo steel displays a higher dislocation density, accompanied by dislocation entanglement phenomena, and contains a small amount of residual austenite, while granular ε-carbides are clearly precipitated in the C-Mn-Cr steel. The C-Mn-Mo steel achieves its best performance at a cooling rate of 25 °C/s, whereas the C-Mn-Cr steel only needs to increase the cooling rate to 35 °C/s to attain a similar comprehensive performance to the C-Mn-Mo steel.

A new strategy for highly wear-resistant ball using carbon nanotube composites: Study on the impact wear resistance and interfacial bonding mechanism

Traditional low-alloy wear-resistant steel balls have a complex and costly manufacturing process, resulting in poor wear resistance. Fortunately, carbon nanotubes offer a promising solution due to their elastic modulus, lightweight nature and good wear resistance properties. To obtain exceptional impact wear resistance, novel carbon nanotubes/Fe matrix grinding balls were developed, the impact wear resistance was explored, and the carbon nanotube/Fe matrix interfacial bonding mechanism was revealed. The results showed a 30% increase in wear resistance after 2 h of impact-abrasive wear tests, as compared to traditional wear-resistant steel balls (B3). In the composite wear-resistant balls, carbon nanotubes are distributed along the prior austenite grain boundaries and within the grains, hindering the growth of austenite grains and increasing the dislocation density, resulting in fine grain strengthening and dislocation strengthening. At the carbon nanotubes/Fe interface, chemical reactions occurred at the nanotube defects, forming Fe3C, and the presence of Fe3C strengthened the interfacial bonding effect through pinning. During the process of impact-abrasive wear, the carbon nanotubes within the composite grinding ball acted as a bridge and formed a lubricating film, exhibiting exceptional wear resistance.

Comparative Experiment of Abrasion-Corrosion-Sliding Wear Performance of Two Kinds of Low Alloy Wear-Resistant Steel.

There is a serious wear problem in the middle plate of scraper conveyors, which causes the problems of high transportation cost, low efficiency, and a lot of material waste. Therefore, it is necessary to study the wear performance of middle plate materials. A new high-titanium low alloy wear-resistant steel (ZM4-13) and a typical material (NM400) for middle plates are studied in this paper. The findings show that the mass loss of ZM4-13 and NM400 rises with the increase of coal gangue percentage. They do not increase monotonically with the change of pH value, and there is a critical value: the critical value of NM400 is between 6–8, and the critical value of ZM4-13 is between 7–9. When the pH value is less than the critical value, the mass loss decreases with the increase of pH value; when the pH value is greater than the critical value, the mass loss increases with the increase of pH value. Under the condition of high gangue and neutral solutions, ZM4-13 has better wear resistance. Its wear resistance can reach up to 1.09–2.10 times compared with NM400. The in-situ precipitated TiC particles are dispersed in ZM4-13. The high hardness of the TiC precipitation area in ZM4-13 hinders the plowing of hard particles and the plastic deformation of surface materials, so ZM4-13 is more wear-resistant than NM400, especially suitable for the harsh working conditions of coal mine production.

The Effect of Rare Earth Cerium on Microstructure and Properties of Low Alloy Wear-Resistant Steel

With the continuous expansion of the application field of low alloy wear-resistant steel, higher processing plasticity and toughness are prioritized on the basis of ensuring strength and hardness. In this article, a low alloy wear-resistant steel Hardox400 was studied: by adding a mass fraction of 0.0030% of rare earth cerium as microalloying treatment, the pilot scale simulation of the rare earth wear-resistant steel was carried out using vacuum induction furnace and a four-high reversible laboratory mill. The effects of the rare earth on the occurrence state of the inclusions, microstructure, mechanical properties and wear resistance of the steel were studied by means of optical microscope (OM), scanning electron microscope (SEM) and wet sand/rubber wheel wear tester. The results show that the fine spherical CeAlO3, CeAlO3-MnS and elliptical Ce2S2O-CaO are formed by adding 0.0030% Ce, which enhances the binding force between the inclusions and matrix. The addition of rare earth Ce helps to refine the as-cast structure, prevent the transformation of proeutectoid ferrite of overcooled austenite and promotes the formation of bainite ferrite, whilst simultaneously increasing the yield strength, yield ratio and surface hardness, especially the low-temperature impact toughness approximately between −40 °C~−20 °C of the tested steel. Simultaneously, the ability to resist abrasive embedment and crack propagation is enhanced, and the wear resistance is obviously improved. The research results will provide a reference for the development of high-quality rare earth wear-resistant steel utilizing national featured resources.

Effect of heat treatment on microstructure and mechanical properties of low-alloy wear-resistant steel NM450

In this study, we investigated the effects of the quenching and tempering temperatures on the microstructure and mechanical properties of low-alloy wear-resistant steel NM450. The quenching temperatures were 870 °C–1200 °C, and held for 36 min. After quenching with 910 °C, the tempering temperatures were 200 °C–600 °C for 60 min. The results showed that as the quenching temperature increasing, the original austenite grain size increased and the proportion of high-angle grain boundaries gradually decreased, which was detrimental to the toughness of the steel. The inter-lamellar-retained austenite remaining in the martensite lath during quenching satisfied the Kurdjumov-Saches relationship with martensite. At the tempering temperatures lower than 250 °C, carbon atoms precipitated in the form of fine carbides, which improved the yield strength of the steel. With the increasing of the tempering temperature, the activity of the carbon atoms increased, the size of the carbides increased, the effects of solid solution strengthening and precipitation strengthening weakened, so the tensile and yield strengths of the steel decreased. The low-alloy wear-resistant steel tempering at 250 °C exhibited the satisfactory combination of properties. The quasi-cleavage fracture occurred mainly over the tempering temperature range of 300 °C–400 °C, and the fracture mechanism turned into ductile fracture when the tempering temperature was higher than 500 °C.

Analysis of microstructure and wear resistance of NM400 thick plate

The hardness distribution and microstructure morphology of NM400 low alloy wear resistant steel plate with thickness of 50mm and 60mm were tested and analyzed, and the sliding wear performance of typical measuring points was also analyzed. The results show that the depth of the NM400 (50mm) hardening layer is about 35mm, accounting for about 70% of the plate thickness. The depth of the NM400 (60mm) hardening layer is about 22mm, accounting for about 37% of the plate thickness. With the position of the measuring point gradually away from the surface of the steel plate, the martensite content in the microstructure of NM400 (50mm) and NM400 (60mm) gradually decreased, and the contents of pearlite, bainite and other microstructure gradually increased. The hardness of NM400 (50mm) gradually decreased from 410HV to 335HV, and the hardness of NM400 (60mm) gradually decreased from 410HV to 305HV. The micro-wear morphologies of NM400 (50mm) and NM400 (60mm) at each measuring point are mainly furrow and contact fatigue spalling, and the wear types are mainly abrasive wear and contact fatigue wear. The furrow depth and the number of furrows on the worn surface of the sample at the corresponding measuring point position gradually increased as the measuring point position moved away from the steel plate surface, and the spalling area and the depth of the spalling pit gradually increased. The wear type gradually changed from particle wear to contact fatigue wear.

Effects of alloy elements on mechanical properties of low alloy wear resistant steel

This work is mainly concerning with effects of Carbon, Nickel and vanadium on mechanical properties of low alloy wear resistant steel. the results showed that The experimental steels yielded their best comprehensive properties at 940 °C of quenching and at 200 °C of tempering for 0.33 wt% C steel, at 940 °C of quenching and at 220°C of tempering for 0.38 wt% C steel, and at 920°C of quenching and at 230 °C of tempering for 0.4 wt% C steel, respectively.3% Ni steel yielded the best property at 900 °C quenching and 200 °C tempering, while 5% Ni steel was 920 °C quenching and 200 °C tempering. The best property yielded at 940 °C quenching and 200 °C tempering for the Vanadium addition steel.

Three-body abrasion wear resistance of TiC-reinforced low-alloy abrasion-resistant martensitic steel under dry and wet sand conditions

Increasingly heavy workloads require components of construction machinery to have higher wear resistance, while the application of high-grade low-alloy wear-resistant steel in the machinery manufacturing industry is restricted greatly by its high hardness. Thus, it is of great significance to improve the wear resistance of low-alloy abrasion-resistant steels without increasing their hardness. A series of TiC-reinforced low-alloy abrasion-resistant steels with different hardness was developed by a conventional smelting-casting method. The microstructure of the TiC-reinforced steels was martensite, and micro- and nano-sized TiC particles were distributed in the martensite matrix. The three-body abrasive wear behaviors of a series of TiC-reinforced steels and conventional steels under dry and wet sand conditions were studied using dry and wet sand/rubber wheel testing machines, respectively. Under dry sand conditions, the main wear mechanism of TiC-reinforced steels was plastic deformation and fatigue spalling, and the wear resistance of the TiC-reinforced steels was more than 1.5 times that of conventional steels with the same hardness. Under wet sand conditions, the wear mechanism of TiC-reinforced steels was slight micro-cutting and peeling, the relative wear resistance of the TiC-reinforced steels was more than 1.4 times that of conventional steels.

New High-Hardness Low-Alloy Wear-Resistant Ledeburitic Steel and the Prospects of Its Application at Negative Temperatures

The structure, the mechanical properties, and the impact toughness in the temperature range from +20 to –70°C of a new low-alloy wear-resistant ledeburitic 220Kh2FYu steel are studied. After proper heat treatment, the steel is shown to have the structure of a natural precipitation-hardened composite material and a high hardness (68–70 HRC). The developed steel is compared with 12Kh2N4VA steel.

Comparison of Sliding Wear Properties of 400 Grade Low Alloy Wear-resistant Steels with Different Microstructure

Comparative study on sliding friction and wear properties of low alloy wear-resistant steel Hardox400 and NM400 at room temperature using Retc multi-function friction and wear tester. The hardness, microstructure and wear surface morphology of the test steel were compared and analyzed by microhardness tester, optical microscope (OM) and scanning electron microscope (SEM). The results show that the wear mechanism of the two kinds of test steels is mainly manifested as abrasive wear and fatigue wear. The Martensite-Bainite Dual Phase Structure in Hardox400 has a good match of strength and toughness, and the sliding wear performance is better than the NM400 of martensite structure.

Study of the three-body impact abrasive wear behaviour of a low alloy steel reinforced with niobium

In order to improve the wear resistance of steel, a new Nb-added reinforced low-alloy wear-resistant steel was developed, and the wear behavior of the three-body impact abrasive was systematically studied under the impact energy of 0.5J, 2.5J, 4J, 5J. Tensile testing, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nanoindentation were used to characterize the mechanical properties, microstructure evolution and wear mechanism of steel. The experimental results show that NB05 (0.05 wt%-Nb) steel with smaller size lath martensite has higher strength performance and better impact wear resistance than NB0 (0 wt%-Nb) steel. During three-body impact abrasive wear tests, the corrected wear rate was less under higher impact energy for both steels, and the NB05 steel owned less wear rate than NB0. The main strengthening mechanisms of the wear layer were newly formed martensite twins, niobium precipitates, high density dislocations and the formation of nanoscale grains for the NB05 steel. The wear mechanism of the wear layer is mainly reflected in buffering, lubrication and protection of debris.

Influence of Ni content on impact-abrasion wear resistance of medium-carbon low alloy cast steel

Medium-carbon low alloy wear-resistant cast steel with different Ni contents (0.08 mass%, 0.77 mass%, 1.74 mass%, 2.43 mass%) were heat treated at 1050 °C, followed by water quenching and tempering at 250 °C. The influence of Ni content on the microstructure, hardness, impact toughness and abrasive resistance of the cast steel were investigated. The results showed that the Ni contents increasing hindered the transformation of martensite phase by reducing martensite transformation start temperature (Ms) and martensite transformation finish temperature (Mf). The fine martensite phase after quenching improved the hardness, impact toughness and wear-resistance of the cast steel. The cast steel with low Ni content (0.08% or 0.77%) consists of lath tempered martensite, while the microstructure turns to mixed lath martensite and lamellar twin martensite with higher Ni content. The cast steel with 1.74% Ni showed a hardness of HRC49.5, an impact absorbing energy with V-notch impact absorbing energy of 16.7 J, and the best wear resistance among the samples.

Effect of TiC particles on three-body abrasive wear behaviour of low alloy abrasion-resistant steel

Low alloy abrasion resistant steel is an indispensable material used in the machinery manufacturing industry. In order to further improve its wear performance without increasing its hardness, a series of low alloy wear resistant steel reinforced with TiC particles was developed. The microstructures were characterized by SEM and TEM. The three-body abrasive wear behaviour of experimental steels has been studied using dry sand rubber wheel testing machine under different applied loads, abrasive particles, and rubber wheel rotation speeds. The results showed that the microstructure of the TiC-reinforced low alloy abrasion-resistant steel consisted of a martensite matrix and nano- and micro-sized TiC particles. Although the TiC particles consumed the C element in the matrix, thus reducing the hardness and strength of the experimental steels, the wear resistance did not decrease. The wear resistance of TiC-particle-reinforced steels was proportional to the density of the TiC particles. Furthermore, the worn surface morphology indicated that the abrasive wear mechanism of TiC-reinforced experimental steels was mainly plastic deformation, fracture, and fatigue, which is different from the micro-cutting observed in traditional low alloy abrasion-resistant steel. The different wear mechanism will aid in improving the wear performance of the steels.

Effects of using (Ti,Mo)C particles to reduce the three-body abrasive wear of a low alloy steel

The use of high-grade, low alloy abrasion resistant steels has been limited due to the effects of their high hardness on their formability, machinability, and weldability. In order to increase the wear resistance of the steel without increasing hardness, a new low alloy wear resistant steel reinforced with (Ti,Mo)C particles was developed. The three-body abrasive wear behaviour of the experimental steel has been studied using a standard dry sand rubber wheel wear testing procedure under applied loads of 45 N and 130 N. Experimental observations revealed that nano- and microparticles are uniformly distributed in the martensitic matrix. The analysis of worn surfaces including longitudinal sections of the surfaces showed that the particles can effectively resist micro-cutting, due to which, the main wear mechanism of the experimental steel was through formation of pits and other indications of surface fatigues. Typically, the abrasion resistance of the experimental steel reinforced with particles was, respectively, 1.6 and 1.8 times that of a traditional low alloy wear resistant steel under applied loads of 130 N and 45 N.

TEM Analysis of Precipitates in a Low Alloy Wear Resistant Steel and Correlating with its Corrosion Behaviour

Wear-resistant low alloy steels containing elements like Cr, Mo, attain their properties due to precipitation of carbides upon heat treatment. These steels are widely used for components in earthmoving and mining equipment. Even though the mechanical properties and wear behaviour of these steels are studied extensively, the studies on nature of carbide precipitation and their influence on corrosion behaviour are very rare. The present work attempts to correlate the microstructure with corrosion properties of low alloy wear resistant steel. After quenching from hot working temperature of about 900 °C, the alloy is subjected to tempering at two different temperatures i.e. 150 °C & 300 °C for durations of 1 h and 4 h. Two competitive process occur simultaneously effecting the hardness of the alloy during tempering i.e. (i) Softening due to transformation of martensite with depleting carbon (ii) Increase in hardness due to formation of carbide precipitates in the matrix. Transmission electron microscopy (TEM) of as quenched condition revealed fully martensite structure in the alloy. TEM investigation of 150 °C/ 4 h tempering condition, revealed presence of some amount of martensite and fine carbide precipitates in the alloy. TEM micrographs of 300 °C/ 4 h condition revealed relatively coarse carbides in a softer ferrite matrix. The presence of martensite and fine precipitates, resulted in relative improvements in wear and corrosion resistance respectively, for the alloy tempered at 150 °C for 4 h, when compared to the alloy tempered at 300 °C for 4 h.

Effect of tempering temperatures on microstructures and properties of 0.28C–0.22Ti wear-resistant steel

ABSTRACTThe microstructures and properties of a 0.28C–0.22Ti low-alloy wear-resistant steel at different temperatures from 200 to 600°C was experimentally studied. It is shown that the wear resistance of the steel is not monotone changing with its hardness and strength. With the increase of the tempering temperature, the tensile strength and the hardness of the steels were gradually declined; however, the wear resistance was first decreased and then increased. The TiC particles can be divided into two classes: the small TiC particles (about 0.3–0.4 µm in diameter) and the coarse TiC particles (1–5 µm in diameter). The small TiC particles can improve the yield strength of the steels, and the coarse TiC particles can improve the wear resistance of the tested steels.

Effect of quenching and partitioning process to low-alloy wear resistant steel

Abstract

Study of uniform quenching technology of NM450 wear-resistant steel

The finite difference method of the low-alloy wear-resistant steel quenching process was studied. The temperature field and cooling rate variation of thickness of 45-mm wear-resistant steel (NM450) were calculated for different quenching practices. The microstructure and hardness of quenched plates were examined. The results indicate that when quenching started, the cooling rate was highest on the subsurface and decreased gradually until the center of the plate. However, as the quenching progressed, the cooling rate distribution along the plate thickness was reversed. The cooling rate increased linearly when the heat transfer coefficient (HTC) increased from 0–10 000 W/m2 K, and then the speed gradually slowed down until achieving the maximum cooling rate. Close to the plate mid-thickness, the maximum cooling rate was easily reached. Compared with high-pressure (HP) quenching and low-pressure (LP) quenching, under the HP + LP continuous quenching mode, it is possible to obtain a high critical cooling rate in the temperature range of 900 °C–400 °C and small temperature difference between the surface and center below 400 °C. The microstructure and hardness distribution on the plate surface for the HP + LP quenching mode indicated 100% martensite on the surface and martensite with a little granular bainite in the plate center, while the hardness difference in the entire steel plate was less than 7%. This study provided guidance for the formulation and optimization of wear-resistant steel.

Effects of Normalizing and Tempering Temperature on Mechanical Properties and Microstructure of Low Alloy Wear Resistant Steel Casting

Influences of normalizing and tempering temperature on mechanical properties and microstructure of steel casting were investigated in this paper. The results showed that as the normalizing temperature increased, tensile strength increased, while tensile stretch increased slowly at first and decreased at last. Steel casting got best comprehensive mechanical properties after a 970°C normalizing treatment. Normalized at 970°C and tempered at the rage of 500 °C and 550°C, steel casting got best comprehensive mechanical properties. The relation between mechanical properties and temperature was gotten using Matlab Software. The microstructure was ferrite and pearlite after normalizing, and tempered sorbite after high tempering.