16MnCr5 Steel Research Articles

Elevated Temperature Tribological Behavior of Duplex Layer CrN/DLC and Nano Multilayer DLC-W Coatings Deposited on Carburized and Hardened 16MnCr5 Steel

This study investigates the impact of temperature on the tribological performance of duplex layer CrN/DLC and nano-multilayers DLC-W coatings deposited using hybrid PVD-PECVD techniques on carburized and hardened 16MnCr5 discs cut from internal combustion engines valve tappets. Reciprocating dry sliding experiments were conducted at 25 °C, 150 °C, 200 °C, and 250 °C to analyze the high-temperature tribological behavior of the coatings. The wear mechanisms were characterized using SEM, EDS mapping, Raman spectroscopy, and nanoindentation. The lowest coefficient of friction was obtained for CrN/DLC at 25 °C. The CrN/DLC coefficients of friction (COF) increase with temperatures due to increasing adhesive wear. Similarly, DLC-W exhibited a comparable trend with increasing temperature from 25 °C to 250 °C. Both coatings’ wear resistance decreased with higher temperatures due to the transformation of sp3 C bonds to sp2 C bonds, facilitating the plastic deformation of the coatings and afterward of the substrate. The CrN/DLC displayed superior wear resistance to the DLC-W coating across all temperatures. The DLC-W multilayer coating showed poor wear resistance above 150 °C, being completely removed during the testing. Compared to both coatings, the uncoated 16MnCr5 discs exhibited higher coefficients of friction and wear rates at all temperatures. Predominant wear mechanisms observed in the coated discs were adhesive and abrasive. The study revealed a decrease in the coatings’ structural and mechanical properties with rising temperatures. Hard abrasive WC particles were identified as contributing to increased wear rates in the multilayer DLC-W coatings.

Influence of electrophysical characteristics of plasma electrolytic treatment of 16MnCr5 structural alloy steel on structural and phase changes in the surface and its tribological properties

The possibility of using plasma electrolytic technologies for surface treatment of 16MnCr5 steel in order to increase its wear resistance is shown. The influence of electrophysical characteristics of plasma electrolytic treatment on structural-phase changes of the surface and its tribological properties is studied. A comparison of anodic and cathodic variants of diffusion saturation, as well as subsequent polishing on the results of surface modification is carried out. The complex effect of surface layers strengthened above 1100 HV, including iron carbide and nitride, martensite and retained austenite, to a depth of up to 250 μm with the preservation of a viscous core and the formation of a relatively homogeneous surface with reduced roughness on increasing wear resistance has been revealed. The features of tribological behavior of surfaces formed under different electrophysical parameters of processing, mainly related to the difference in surface microrelief, are shown. The correlation of the Kragelsky-Kambolov criterion as a complex assessment of surface roughness with its wear resistance is shown. The influence of changes in sliding speed and friction load on the occurrence and development of leading processes that determine the intensity and nature of destruction of friction surfaces is established.

The effect of various treatment parameters in duplex plasma nitrided and diamond-like carbon coating on high-cycle fatigue and fretting fatigue lifetimes of piston pin 16MnCr5 steel

This paper investigates the impact of duplex plasma nitriding and diamond-like carbon (DLC) coatings on the pure fatigue and fretting fatigue properties of 16MnCr5 steel extracted from industrial piston pins used in combustion engines. Two different nitriding and DLC coating processes were performed: "DLC-A" and "DLC-B". The Raman spectrometry and microhardness tests were utilized to evaluate the formation of DLC coating on the sample. Subsequently, the pure and fretting fatigue tests (at 350 MPa and under 100 Hz of the frequency) were performed on as-cast and DLC-coated specimens to obtain the effect of coatings on the fatigue behaviors of the 16MnCr5 steel. Finally, the formation of the DLC layer and the fracture mechanisms were also briefly investigated using field-emission scanning electron microscopy. Then, the obtained results demonstrated that DLC coating ("DLC-B") increased the fatigue lifetime of 16MnCr5 steel by 47.7 % and 85.3 % in pure and fretting fatigue conditions, respectively. This layer can improve the surface properties of engineering materials and components, which can enhance the fatigue lifetime by increasing microhardness and compressive residual stress, reducing wear and friction, and improving adhesion between the substrate and coating. However, due to the white layer, the “DLC-A” improperly enhanced the material performance.

Study on the Tribological Properties of DIN 16MnCr5 Steel after Duplex Gas-Nitriding and Pack Boriding.

DIN 16MnCr5 is commonly used in mechanical engineering contact applications such as gears, joint parts, shafts, gear wheels, camshafts, bolts, pins, and cardan joints, among others. This study examined the microstructural and mechanical properties and tribological behavior of different surface treatments applied to DIN 16MnCr5 steel. The samples were hardened at 870 °C for 15 min and then quenched in water. The surface conditions evaluated were as follows: quenched and tempered DIN 16MnCr5 steel samples without surface treatments (control group), quenched and tempered DIN 16MnCr5 steel samples with gas-nitriding at 560 °C for 6 h, quenched and tempered DIN 16MnCr5 steel samples with pack boriding at 950 °C for 4 h, and quenched and tempered DIN 16MnCr5 steel samples with duplex gas-nitriding and pack boriding. Microstructure characterization was carried out using metallographic techniques, optical microscopy, scanning electron microscopy with energy-dispersive spectroscopy, and X-ray diffraction. The mechanical properties were assessed through microhardness and elastic modulus tests using nanoindentation. The tribological behavior was evaluated using pin-on-disc tests following the ASTM G99-17 standard procedure under dry sliding conditions. The results indicated that the surface treated with duplex gas-nitriding and pack boriding exhibited the highest wear resistance and a reduced coefficient of friction due to improved mechanical properties, leading to increased hardness and elastic modulus.

Experimental Analysis of Effect of Machined Material on Cutting Forces during Drilling.

Current research studies devoted to cutting forces in drilling are oriented toward predictive model development, however, in the case of mechanistic models, the material effect on the drilling process itself is mostly not considered. This research study aims to experimentally analyze how the machined material affects the feed force (Ff) during drilling, alongside developing predictive mathematical-statistical models to understand the main effects and interactions of the considered technological and tool factors on Ff. By conducting experiments involving six factors (feed, cutting speed, drill diameter, point angle, lip relief angle, and helix angle) at five levels, the drilling process of stainless steel AISI1045 and case-hardened steel 16MnCr5 is executed to validate the numerical accuracy of the established prediction models (AdjR = 99.600% for C45 and AdjR = 97.912% for 16MnCr5). The statistical evaluation (ANOVA, RSM, and Lack of Fit) of the data proves that the drilled material affects the Ff value at the level of 17.600% (p < 0.000). The effect of feed represents 44.867% in C45 and 34.087% in 16MnCr5; the cutting speed is significant when machining C45 steel only (9.109%). When machining 16MnCr5 compared to C45 steel, the influence of the point angle (lip relief angle) is lower by 49.198% (by 22.509%). The effect of the helix angle is 163.060% higher when machining 16MnCr5.

Statistical Models for Predicting Wear and Friction Coefficient of Valve Tappet Using ANOVA

The focus of this study is to propose statistical models for predicting wear and coefficient of friction of the 16MnCr5 steel valve tappet using the analysis of variance (ANOVA). The 16MnCr5 steel valve tappet was fabricated from a steel strip and thermochemically treated by carburizing, quenching, and tempering. Under dry conditions, tribological tests were performed for 16MnCr5 steel valve tappet with a ball-on-plane configuration in a reciprocating slide using an Optimol SRV® v4 device. Subsequently, the results of the coefficient of friction (COF) and the wear rate were then analyzed using the ANOVA. Regression analysis was used to derive the predictive equations for both friction coefficient and wear rate. The applied load was found to be the most significant parameter affecting the COF and wear rate. The proposed statistical models has 88 - 92% percent reliability. These models can be beneficial for predicting the tribological operating conditions for the 16MnCr5 steel valve tappet to avoid premature failure within the tested load and temperature conditions.

Development of a Parametric Model for Calculating Cutting Forces in External Cylindrical Turning of 16MNCR5 Steel

The paper presents a mathematical model for calculating cutting forces during the machining of 16MnCr5 steel using the Sandvik CNMG 120408 16P25T tool. The modeling process involved the use of a test rig constructed based on the 16Д25 machine, which enabled the measurement of real values of spindle speed, longitudinal feed, cutting depth, and cutting forces. The results transmitted to a computer through the LTR-EU-8 workstation, equipped with galvanic isolated LTR modules and a synchronization interface. Based on the experimental results, the theoretical model demonstrated a deviation from actual measurements of no more than 4.72%. The study provides evidence that the cutting force calculations commonly presented by leading tool manufacturers are inherently overestimated. he difference in cutting forces can be 9%.

Experimental investigation on the surface quality of WEDM machined 20MnCr5 steel for gear application

This experimental study investigates the Wire-cut Electrical Discharge Machining (WEDM) of 20MnCr5 steel, a low alloy steel grade material which is intended for the production of gears, shafts and other parts which need high surface hardness and wear resistance. WEDM is a crucial manufacturing process for producing gears, shafts, spindles, and various mechanical components. The investigation focuses on three key performance parameters: profile error, material removal rate (MRR), and surface roughness (SR), employing five WEDM parameters—wire feed (Wf), wire tension (Wt), servo voltage (SV), discharge arc-off time (Toff), and arc-on time (Ton) - by employing the Taguchi L27 orthogonal array. The study reveals that, in comparison to arc-on time and servo voltage, wire feed rate and tension have a lesser impact. Higher arc-on time and servo voltage result in increased profile error, while reduced wire tension values elevate surface roughness. Recast layer formation has been explored under different WEDM input parameters, revealing its dependence on arc-on time, voltage, wire tension, and feed rate. Higher voltage leads to uneven surfaces with larger globules and deep craters, contributing to a thicker recast layer at higher arc-on time and servo voltage.

Effect of martensitic reversal and grain size on the corrosion and wear behaviour of Cr-Mn steel

In this study, the effect of corrosion and wear behaviour of Cr-Mn steel on fine grains were investigated. The sample were solution annealed (SA) for 1 h at 1050 °C and then cold rolled (CW) to 30%. Further the cold rolled sample were thermally aged (CW + TA) 900 °C for four hours. The findings showed that under the 10 N applied load, wear resistance increased with an increase in hardness and martensite fraction of the cold worked (CW) samples. However, the Cr-Mn steel had the superior wear resistance after thermal ageing (TA). In microstructural examination deformation bands can also be visible in cold work samples. The analysis implies that the γ-phase is apparent across all peaks within the spectra of SA samples. In instances involving 30% cold work, prominent α′ martensite peaks were observed, accompanied by minimal ε-martensite peaks. Electrochemical impedance spectroscopy (EIS) analysis discloses a reduction in impedance and a concurrent increase in the defect density of the passive film. The CW+TA structure with good inclusive performances created an early constant hardened layer, which didn’t delaminate and peel off prematurely, thereby effectively increasing the wear resistance, according to analysis of the wear mechanism. The results also concluded that the corrosion resistance of CW sample decreases due to SIM formation, however CW+TA sample provide better corrosion resistance due to smaller and refined grain size.

Plain and fretting fatigue characteristics of 16MnCr5 steel under cyclic bending loading with the application of engine piston pin

The current study examined the plain fatigue and the fretting fatigue behaviors of the piston pin alloy (16MnCr5 steel) under fully-reversed rotating bending loading. The standard fatigue testing sample was cut out from the piston pin used in internal combustion engines. Furthermore, the failure mechanisms of samples were studied using field emission scanning electron microscopy. The obtained result indicated that the fatigue lifetime of 16MnCr5 steel was significantly affected by the fretting damage. The investigation of the failure mechanisms determined that the fracture behavior of the specimens under the plain fatigue and fretting fatigue conditions was brittle; however, it was considerably influenced by the casting defects in the samples. The test results can merely be used to compare the fatigue performance of the studied material under different conditions. More naturalistic experiments are required for further optimization in designing components made from this material to improve their reliability and service life, especially in contacting surfaces under rotating bending conditions.

The Structure of Boride Diffusion Coatings Produced on Selected Grades of Structural Steels

In the article the microstructure and phase composition of boride coatings deposited on selected structural steels were investigated. The boride coatings were produced using pack cementation method using commercial EKABOR-2 mixture containing of 50 wt. % of new and 50 wt. % of used powder. Boride coatings were deposited on alloyed structural steels grades (PN/EN 10084 standard): 16MnCr5, 18CrNiMo7-6, 41CrAlMo7 42CrMo4. Cylindrical samples with a diameter of 30 mm and a height of 30 mm were boronized in powder at 1000°C for 2, 4 and 6 hours in an argon atmosphere. The process was carried out in an industrial CVD Bernex BPX 325S device. The microstructure was analyzed using scanning electron microscope Phenom XL equipped with EDS spectrometer. The XRD phase analysis was conducted using XTRa diffractometer (ARL). The thickness as well as phase composition was analyzed on coatings formed on each grades of steels. The most of obtained boride coatings were characterized by single-phase structure (Fe2B). The formation of brittle FeB phase was detected only on 16MnCr5 steel grades steels.

Identification of Intermetallic Phases Limiting the Growth of Austenite Grains in the Low-Pressure Carburizing Process

This article presents the results of a study to identify intermetallic phases whose role is to limit austenite grain growth in the low-pressure carburizing process. A drawback of high-temperature low-pressure carburizing is the austenite grain growth during the process. Using low-pressure carburizing with pre-nitriding technology (PreNitLPC®) offers the possibility of reducing austenite grain growth. This technology involves the application of doses of ammonia during the heating stage of the steel, at the carburizing temperature, to introduce nitrogen into the surface layer of the steel and to form nitrides. It is these phases that cause restrictions on austenite grain growth during carburizing. The research carried out in this article was aimed at identifying these phases. The research was carried out on one of the basic steels used for carburizing—16MnCr5 steel. The carburizing of this steel with and without pre-nitriding was performed, followed by an evaluation of the austenite grain size after these processes and the identification of the intermetallic phases present in the surface layer of the steel.

Static load-carrying behavior and material properties of additively manufactured gears (PBF-LB/M, 16MnCr5)

PurposeNumerous metals can be processed using the additive manufacturing process laser-based powder bed fusion of metals (PBF-LB/M, ISO/ASTM 52900). The main advantages of additive manufacturing technologies are the high degree of design freedom and the cost-effective implementation of lightweight structures. This could be profitable for gears with increased power density, combining reduced mass with considerable material strength. Current research on additively manufactured gears is focused on developing lightweight structures but is seldom accompanied by simulations and even less by mechanical testing. There has been very little research into the mechanical and material properties of additively manufactured gears. The purpose of this study is to investigate the behavior of lightweight structures in additively manufactured gears under static loads.Design/methodology/approachThis research identifies the static load-carrying capacity of helical gears with different lightweight structures produced by PBF-LB/M with the case hardening steel 16MnCr5. A static gear loading test rig with a maximum torque at the pinion of T1 = 1200 Nm is used. Further focus is set on analyzing material properties such as the relative density, microstructure, hardness depth profile and chemical composition.FindingsAll additively manufactured gear variants show no failure or plastic deformation at the maximum test load. The shaft hub connection, the lightweight hub designs and the gearing itself are stable and intact regarding their form and function. The identified material characteristics are comparable to conventionally manufactured gears (wrought and machined), but also some particularities were observed.Originality/valueThis research demonstrates the mechanical strength of lightweight structures in gears. Future research needs to consider the dynamic load-carrying capacity of additively manufactured gears.

Application of the theory of critical distances for fatigue life assessment of spur gears

This study evaluates the effectiveness of the theory of critical distances (TCD) method in determining the fatigue lifetime of a spur gear. A comprehensive characterization of the material parameters necessary for critical distance calculation was performed, including the fatigue limit and crack growth threshold, as well as σ-N and ε-N curves for 16MnCr5 steel. A variety of TCD methods were applied to analyse the component, including the point method, line method, volume method, and mesh control. The results indicate that overall, the TCD method is a reliable and accurate way to predict the fatigue lifetime of spur gears. The study reveals a strong correlation between predicted and experimental crack locations and fatigue lifetime, suggesting accurate prediction using TCD and the Smith-Watson-Topper parameter. Although all TCD methods, when applied correctly, yield similar results, mesh control is the faster method and is therefore more attractive from an industrial perspective. The results of this study provide valuable insight for engineers and researchers in the field of fatigue analysis of spur gears and similar mechanical components.

Recyclate-containing magnesia-carbon refractories – Influence on the non-metallic inclusions in steel

The fabrication of MgO–C refractories containing MgO–C recyclates is a current approach for saving resources and energy. However, it must be ensured that the steel quality is not adversely affected, particularly with regard to non-metallic inclusions. The present study investigates MgO–C refractories containing different proportions of MgO–C recyclates (up to 83%) in contact with 16MnCr5 steel melt and a slag. A recyclate-free MgO–C material served as a reference. The tests were performed in a steel-casting simulator. By an automated feature analysis of the solidified steel, manganese sulfide and complex alumina-manganese sulfide inclusions were found to be the predominant ones in all steel samples. No negative influence of the recyclate on the inclusion count and the size distribution of the inclusions, the latter being determined for the sum of alumina and alumina-manganese sulfide as well as for the manganese sulfide inclusions, was observed.

Investigations on Case Hardening of an Additive Manufactured Steel 20MnCr5 (via PBF-LB/M)

Abstract As an additive manufacturing process, powder bed fusion of metals using a laser beam (PBF-LB/M) enables the near-net-shape production of complex components in a single step. In combination with case hardening, it will thus be possible in the future to produce lightweight, functionally integrated transmission components characterized by high-strength surface layers with a sufficiently tough component core. However, the process-related new initial conditions resulting from very high solidification rates in PBF-LB/M may mean that case hardening of PBF-LB/M materials with standard parameters achieves different case hardening results than have been usual in the past. This hypothesis was investigated in the present work using the case hardening steel 20MnCr5 (material number 1.7147) after successful development of industry-relevant PBF-LB/M parameters. Besides the convincing results regarding microstructure, hardness and carbon depth profiles, case hardening with standard parameters led to irregular grain growth due to holding at high temperatures for several hours during carburization.

Exploring the origins of surface cracks in forged ingots: Impurity element influence and temperature-induced formation of detrimental phases in case hardening steel

Surface hot shortness is a critical defect affecting the performance and reliability of steel components. This study investigates the factors influencing surface hot shortness in DIN 16MnCr5 steel, with a particular focus on the role of impurity elements and temperature. Experimental analysis reveals that copper and zinc, as impurity elements, play a significant role in the formation of detrimental phases and the initiation of surface cracks. Copper enrichment occurs due to its lower affinity to react with oxygen, resulting in its aggregation at the oxide layer/iron interface. Zinc contamination contributes to the formation of intermetallic phases and the initiation of hot shortness, likely due to its low melting point and reactivity. Furthermore, the impact of temperature during hot tensile testing on the ductility and formation of detrimental phases is investigated. Below 950 °C, fractures primarily occur due to proeutectoid ferrite formation at grain boundaries, with limited formation of Cu-rich phases. However, temperatures above 950 °C exhibit increased Cu-rich phase formation, leading to decreased ductility and the formation of hot cracks. The critical temperature range of 1000 °C shows minimum ductility and the highest content of Cu-rich compounds.Grain boundary penetration of Cu-rich melt is identified as a crucial mechanism in the nucleation and propagation of cracks during surface hot shortness. Exceeding a certain copper concentration along grain boundaries leads to the formation of a molten phase at the crack tip, facilitating wetting of the grain boundaries and the subsequent formation of surface cracks. Understanding the influence of impurity elements, such as copper and zinc, as well as the effect of temperature on surface hot shortness is essential for mitigating this defect and improving the performance of steel components. The findings of this study contribute valuable insights toward the development of effective strategies for preventing and controlling surface hot shortness in DIN 16MnCr5 steel.

Comparison of forming processes for micro textured cups

Friction losses are present in all kinds of technical systems. This is always associated with additional energy consumption, which can be partly avoided as it arises. Energy savings can be achieved by a wide range of approaches. The application of friction reducing coatings on bodies in relative motion is widespread. The coating of parts is however only suitable to a limited extent for the production in large batches. Therefore, research approaches consider alternative methods to achieve friction reductions. A promising approach is the integration of miniaturized pockets on the surface of the component. In lubricated contacts, the lubricant can then accumulate in these indentations. The relative motion between two bodies thus builds up a hydrodynamic pressure and consequently reduces friction. Forming technology is suitable for the efficient production of metallic components in large quantities. The aim of this study is therefore to identify challenges in the integration of micro coining in established forming processes. Two processes from sheet metal forming and bulk metal forming are investigated. In a combined experimental and numerical approach, process-specific challenges are derived regarding the texturing process and the numerical process modelling for combined micro coining. The analysis is carried out on a cup geometry, as used in the automotive sector as tappets in the valve train. The case hardening steel 16MnCr5 (1.7131) is used as workpiece material.

Scan strategy induced microstructure and consolidation variation in the laser-powder bed fusion (L-PBF) additive manufacturing of low alloy 20MnCr5 steel

The paper focuses on the effect of the scanning strategies on the microstructural evolution, defect formation, and macro-hardness performance of laser-powder bed fusion (L-PBF) produced samples of low alloy 20MnCr5 steel. Respect to the scanning strategies, advanced characterization techniques were employed to study (i) as-built microstructure, (ii) inclusion size and distribution, and (iii) details of compositional variation around porosity and within the build. Microstructural characterization shows that the chessboard scanning strategy can provide a favorable microstructure for the improvement of mechanical performance. However, macro-hardness results show a lower mechanical performance compared to the linear scanning strategy samples, which is contradicted by the improved microstructure. Experimental results reveal that the chessboard scanning strategy promotes the oxidation reaction and in-situ oxide (SiO2) formation in L-PBF, which leads to significant defect formation due to the excessive thermal profile from the overlap of the laser. This has been validated through finite element analysis and thermodynamic computation. The advantages of microstructural improvement using the chessboard strategy can only be realized with strict control of the metallurgical quality during the L-PBF process. Thermal profile optimization and oxygen elimination during the L-PBF process could be critical for the improved metallurgical quality and superior mechanical performance of the as-built components.

Corrosion and abrasion behavior of high-temperature carburized 20MnCr5 gear steel with Nb and B microalloying

This paper investigates the effect of Nb and B microalloying on the wear and corrosion resistance of 20MnCr5 steel after high-temperature carburization at 950 °C. The abrasion and corrosion performance of the steel was compared using electrochemical experiments and dry sliding wear tests. The results show that Nb microalloying reduces the size of residual austenite, thereby improving the wear resistance of 20MnCr5 steel. Furthermore, the combination of Nb and B microalloying reduces the amount of residual austenite, leading to further improvements in wear resistance. Both microalloying methods reduce the wear scar depth and debris accumulation. The corrosion potentials of 20MnCr5, 20MnCr5Nb, and 20MnCr5NbB are 0.645 V, 0.627 V, and 0.675 V, respectively. The addition of Nb to 20MnCr5 steel results in higher corrosion resistance after carburization due to the refinement of needle-like martensite. However, 20MnCr5NbB steel exhibits low corrosion resistance due to the coarsening of needle-like martensite caused by B microalloying. In summary, this study provides new insights into the effects of microalloying elements on the properties of steel. The findings contribute to a deeper understanding of how to design and manufacture gears and other components with superior wear and corrosion resistance.