Spring Steel Research Articles

Mechanical hardness estimation of heat-treated DIN50Cr3 spring steel utilizing laser-induced breakdown spectroscopy (LIBS) inverse calibration

In various industrial applications, particularly for suspension systems, a range of mechanical properties are required to meet the designer requirements. In the present work, the semi-nondestructive laser-induced breakdown spectroscopy (LIBS) technique was used for the first time to estimate the hardness (HV units) of the light duty low-carbon spring steel DIN50Cr3 through LIBS calibration curves. For this purpose, three distinct spring steel samples, namely DIN50Cr3 were successfully treated by subjecting to various treatment regimes, namely R1 annealing, R2 quenching and R3 normalizing. The calibration curves were constructed using the ratio of ionic to atomic line intensities of LIBS spectra versus the Vickers mechanical hardness as well as microstructural analyses were performed. The mechanical hardness for spring steel DIN50Cr3 subjected to different tempering heat treatment regimes R4, R5 and R6 is then deduced from the calibration curves, and their values were correlated with those obtained from Vickers test. Microstructural analysis was performed using scanning electron microscopy (SEM) and correlated the variation of the obtained hardness level to the microstructural changes accompanying all heat treatment regimes.

Inclusion initiated fracture in spring steel under axial and torsion very high cycle fatigue loading at different load ratios

Inclusion initiated fracture under axial and torsion very high cycle fatigue loading at load ratios R = −1, 0.1 and 0.35 is compared. High strength spring steel with intentionally increased density of aluminate inclusions was tested at ultrasonic frequency. Failures under axial loading started at internal aluminate inclusions at all load ratios, and at aluminate and MnS inclusions in cyclic torsion at positive load ratios. Considering crack initiation at same size aluminate inclusions, a cyclic torsion stress amplitude at the inclusion that is a factor 0.86 ± 0.05 smaller than the cyclic tension stress amplitude has an equally detrimental effect on cyclic strength.

Decarburization of 60Si2MnA in 20 Pct H2O-N2 at 700 °C to 900 °C

The decarburization behavior of a spring steel 60Si2MnA at 700 °C to 900 °C was examined. It was observed that after holding for 20 minutes in 20 pct H2O-N2, thick ferrite layers developed within 750 °C to 877 °C with a maximum thickness of about 100 μm observed at 805 °C to 825 °C, while the ferrite layers were much thinner at 900 °C and 700 °C. Carbon permeability analysis and theoretical calculation were conducted to assess the possibility of forming a ferrite layer. In the permeability analysis, several factors were considered: (1) carbon concentration at the steel surface, which was very likely determined by reaction equilibrium between FeO and dissolved carbon in steel, (2) carbon solubility in ferrite which had a maximum value at about 715 °C, and (3) carbon diffusivity in the ferrite phase. In the ferrite layer thickness calculation, the contribution from carbon diffusion in the austenite phase was also taken into account. While the carbon permeability analysis and ferrite layer thickness calculation showed good successes in predicting the pattern of ferrite layer thickness change with temperature, under the assumption of FeO-ferrite equilibrium the calculated ferrite layer thicknesses at 780 °C to 840 °C did not match the observed values well. Factors contributing to the discrepancy were discussed.

Low Cycle Fatigue behavior of heat treated EN-47 Spring Steel

EN 47 spring steel is a 1% chromium-vanadium type spring steel, which is widely used for landing gears of smaller aircraft, leaf spring and coil spring of vehicles, heavy machinery crank pin, steering knuckles and disc springs for rigidly bolted sections. In this investigation, E-47 spring steel samples were heat treated and microstructure and hardness were observed. Then the samples were subjected to low cycle fatigue analysis along with fractograph. It is witnessed that for 8hrs heat-treated sample has taken 4222 cycles to fail and that is higher than 4hrs sample which is 3375 cycles to failure and an unheated sample which is having 2856 cycles to failure. The strain controlled fatigue life is greatly influenced by the type crack formation during the fatigue test

Fatigue damage, impact toughness and micromechanisms of fracture of spring steel after operation at low climatic temperatures

To solve urgent problems of ensuring the vehicles parts reliability under alternating loads, it is necessary to study the influence of operational conditions on the accumulation of fatigue damage in the material, leading to the appearance of micro- and macrocracks. The purpose of this work is to study the influence of fatigue damage formed in spring steel under operational impacts typical of the cryolithozone on the level of its resistance to brittle fracture. Methods of mathematical statistics and methods of metal research (metallography, fractography, microindentation, mechanical testing, etc.) were used in the work. Two main types of structural damage are identified, differing in scale level: microdamage, reflected by the microhardness parameter, and mesodamages in the form of pores of various diameters. New data on poorly studied fatigue damage accumulation processes under non-stationary loading and their influence on brittle fracture resistance were obtained. Mechanism of the effect of porosity on brittle fracture resistance is associated with the occurrence of deformation processes in the vicinity of pores, as well as during growth and coalescence of pores. The research results can be used to develop methods for obtaining and information processing on the structural damage of materials and to extend the service life of elastic elements of vehicles operating in the cryolithozone.

Numerical simulation of the debonding behavior of fiber reinforced metal matrix composites

Finite element analysis (FEA) is performed for investigating the debonding behavior of fiber reinforced metal matrix composites (MMCs). An Axisymmetric cylindrical and three dimensional solid finite element (FE) models without interface are constructed which consist of a stainless spring steel wire as fiber reinforcement and an aluminium alloy as matrix. Numerical simulation is carried out with both the spherical and cylindrical indenters. The simulation results obtained in this work are compared with the experimental findings reported in the past. The initial part of load–displacement curve for cylindrical indenter is linear in nature as compared to the non linear behaviour with the spherical indenter. This shows that the non linearity is because of the shape of the indenter and not due to other reasons such as incorrect modeling. The coefficient of friction does not affect the response regarding the load–displacement curve. A large gap between the experimental and simulation curves for the elastic region is due to stiffness of the experimental setup. The simulation curve shows continuous increase in the value of load which is due to the absence of definition of failure criterion. The axisymmetric FE model presented in this study shows the capability to simulate the debonding behaviour of fiber reinforced MMCs. However, it can be improved further with the implementation of cohesive layer concept for modeling the fiber–matrix interface. In future work, the FEA of the axisymmetric model with interface using the cohesive zone modeling (CZM) for the interface will be carried out.

Effect of high-pressure H<sub>2</sub> gas on strength of spring steel by means of the internal high-pressure H<sub>2</sub> gas method

Effect of high-pressure H<sub>2</sub> gas on strength of spring steel by means of the internal high-pressure H<sub>2</sub> gas method

Axisymmetric finite element analysis of single fiber push-out test for stainless steel wire reinforced aluminum matrix composites

An axisymmetric cylindrical finite element (FE) model with wire-matrix interface is presented with the objective of evaluating the interfacial properties of stainless steel wire reinforced aluminum matrix composites. It consists of a wire of stainless spring steel 1.4310 (X10CrNi18-8), a matrix of aluminum alloy AA6060 and the interface. The FE model used to model the push-out test which has been developed over a number of years as a mean of quantifying the interfacial properties. The interface with a specified thickness is modeled using the cohesive layer concept where, in addition to the elastic parameters, a damage criterion based on the maximum nominal stress is also defined for the interface. Fracture energy is used to define the damage evolution which describes the rate at which material degrades, once the damage initiation criterion is met. The interface parameters are varied to adopt the model according to the experimental results reported in the past. The simulation results are in qualitative agreement with experimental results regarding the force–displacement graph. The simulation results obtained show the presence of compressive stresses at the top and tensile stresses at the bottom of the interface caused by the bending of the specimen. It indicates that, during fiber push-out test of metal matrix composites where thin-slice geometries are used, interfacial failure initiation favoured by tensile stress field, probably occurs at the bottom of the specimen even in the absence of thermally induced shear stresses. However, modeling the stepwise debonding of interface requires the more sophisticated implementation of interface behaviour concerning failure evolution and the friction between wire and the matrix.

Experimental Studies on Machining EN45 Steel under Dry and MQL using Uncoated Inserts

In owe to the global concern of environment growth and green production acts with use biodegradable and low consumption of lubrications the present paper deals use of MQL in turning EN 45 steel. Literacy over the use of effective production practices increases the efficiency of surface integrity and economical effect of production. With this aspect, the present study deals with of surface roughness characteristic generated while turning EN 45 graded spring steel with uncoated CNMG insert under MQL condition. A total of 27 experiments are performed on a CNC lathe under both Dry and MQL conditions. Surface roughness produced with varying in machining parameter of cutting speed (75, 100, 125 m/min), feed rate (0.1, 0.2, 0.3 mm/rev) and depth of cut (0.3, 0.6, 0.9 mm). Effect of induvial parameter over surface roughness is been clearly pictured out with the graphical representation with comparison under both DRY and MQL conditions. A mathematical model was generated with the experimental results for prediction of roughness within the limits of parameters. ANOVA analysis, feed shows a high contribution towards the surface roughness.

Selection criterion of material filling in ridge grooves for reducing cross-sectional deformation of double-ridged rectangular bent tube

In order to satisfy the further improvement of new communication equipment, filling the ridge grooves on side walls with fillers is the effective method to improve the quality of double-ridged rectangular bent tube in H-typed rotary draw bending. However, how to choose appropriate material filling in ridge grooves to reduce deformation more effectively is a critical issue. Therefore based on the reliable FE models of H-typed rotary draw bending and twice-springback of double-ridged rectangular tube with fillers with different material parameters, a selection criterion of the material of filler to minimize the cross-sectional deformation of bent tube was studied. The selection criterion is that only the height size accuracy of filler should be made sure to be consistent with that of the ridge groove. The strength coefficient K of filler should be considered firstly, and the larger K can reduce the deformation more effectively. The yield strength σs and hardening exponent n can be considered secondly, and filler with higher σs or smaller n can be selected as far as possible. Elastic modulus E may not be taken into account. The reliability of this selection criterion is verified by using 65Mn spring steel filler.

65Mn弹簧钢焊接接头缺陷及焊接性能研究

65Mn弹簧钢焊接接头缺陷及焊接性能研究

Stability of Physically-Loaded Helical Springs used In Smart Fork Lift

In the following section, the behavior of helical compression springs is considered in smart fork lift (established in previous work). We have used commonly used cylindrical and conical shape helical spring as storage devices in which stability defined in term of load-gains, deflections and evaluation of spring-rates. Springs’ rates of both springs were compared on a common platform. Initially both springs (helical-conical) was prepared from the coiled wires. These prepared springs also known as coil springs which regain its original form and position when distorted by the loaded in smart fork-lift apparatus. These coils springs here developed by the applying the heat treatment and quenching processes on the galvanized spring steel material by using the threaded shape fixtures. This prescribed work focused on effect of physically-loaded gains by cylindrical and conical shaped helical spring in smart fork lift. Here, springs worked as mechanical devices to bear the lifting load which differed here greatly in strength and in size depending on changing its parameters. Both the cylindrical and conical shape was made of helically coiled wires with constant clearance between the active coils and able to absorbed external counter-acting loads applied against each other in their axis. One direction deformation in axially format was considered.

Study on corrosion resistance of high-strength medium-carbon spring steel and its hydrogen-induced delayed fracture

The disadvantages of poor corrosion resistance and delayed fracture resistance of high-strength medium-carbon spring steel have significantly limited its application in the construction industry. Therefore, there is a need to improve these characteristics of spring steel. In this paper, the effects of Ti, Cu, and Ni on the microstructure, mechanical properties, corrosion resistance, and hydrogen-induced delayed fracture behaviour of spring steel were investigated by scanning electron microscopy, transmission electron microscopy, electrochemical workstation analysis, neutral salt spray test and hydrogen permeation testing methods. The results showed that the tensile strength of the experimental steel reached 2000 MPa and the yield strength reached 1800 MPa. These values were observed when the quenching and tempering temperatures were 900 °C and 350 °C, respectively; further, the experimental steel had a tempered martensite microstructure at these temperatures. Ti increased the self-corrosion potential of the experimental steel and reduced the self-corrosion current. With an increase in the content of alloying elements (Ti, Cu, and Ni), the depth of the corrosion pits in the experimental steel became shallower and the degree of surface damage was reduced. Moreover, Ti could refine the crystal grains, TiC had high a trap activation energy of hydrogen, and Ti-containing steel had better hydrogen-induced fracture resistance.

Performance optimization of jaw-type rock crushing machine through shaft eccentricity redesign

The recurrent failure of jaw-type crushing machine was traced to an inappropriate external shaft ratio and frequent wear of the jaw of the machine. Current jaw-type crushing machines are designed and constructed with spring steel was improvised with spring steel because of the scarcity of the required material to cast the jaw, which has to be imported whenever there is a failure. The analysis of the relationship between the life span of the jaw of the rock crushing machine to the shaft eccentricity was carried out to determine the external shaft ratio of the machine. The eccentric lobe to impact motion at various positions were analyzed and plotted out for both angular and linear displacements. The analysis and evaluation involved data collection from existing quarries. The results show that an external diameter/offset ratio within the average of 10:1 can be considered for the offset calculation of a jaw-type crusher shaft. The outcome of the result was used to redesign and develop a prototype crushing machine with better output crushing pressure of 13.1×105 kN/m2 and capable of crushing 425–569 kg of rock per hour, depending on the type of rock to be crushed. The machine performed exceptionally well with an efficiency of 95% and is relatively durable compared to high grade imported rock crushing machine.

Assessment of Retained Austenite in Fine Grained Inductive Heat Treated Spring Steel.

Advanced thermomechanical hot rolling is becoming a widely used technology for the production of fine-grained spring steel. Different rapid phase transformations during the inductive heat treatment of such steel causes the inhomogeneous mixture of martensitic, bainitic, and austenitic phases that affects the service properties of the steel. An important task is to assess the amount of retained austenite and its distribution over the cross-section of the inductive quenched and tempered wire in order to evaluate the mechanical properties of the material. Three different analytical methods were used for the comparative quantitative assessment of the amount of retained austenite in both the core and rim areas of the sample cross-section: neutron diffraction—for the bulk of the material, Mössbauer spectroscopy—for measurement in a surface layer, and the metallographic investigations carried by the EBSD. The methods confirmed the excessive amount of retained austenite in the core area that could negatively affect the plasticity of the material.

Design and Fatigue Analysis of Shot Peened Leaf Spring

The paper handles the fatigue and failing analysis of serial shot-peened leaf springs of cumbersome vehicles emphasizing on the impact of shot peening on fatigue life, coping with automotive leaf springs, the shot peening method turns into an important step in production.In the situation of leaf spring suspensions, however, asystematic research of the effect of shot peening about fatigue life isstill required. Experimental stress-life curves are determined with the aid of the usage of investigating clean specimen subjected to shot peening. those test consequences are as compared to corresponding ones identified from cyclic three-point test on shot peened serial leaf springs in order to show the influence of applied heat treatment and shot peening approach on fatigue existence of high-strength used to get leaf spring manufacturing, reliant on the load level. Analyses are performed to explain the effects resulting from shot peening practice on the surface features of the high-strength spring steel under examination. The evaluation of fatigue results shows that almost no life improvement due to production highlighting the importance for mutual variation in parameters of shot peening and thermal treatment so that there is sufficient progress in life

Oxidation of 60Si2MnA Steel in Atmospheres Containing Different Levels of Oxygen, Water Vapour and Carbon Dioxide at 700–1000 °C

The oxidation behaviour of the spring steel 60Si2MnA in atmospheres containing 0–21% (volume per cent) O2, < 20 ppm (part per million) to 17%H2O, with some containing 8%CO2, at 700–1000 °C was investigated. The oxide scale thicknesses formed in both 17%H2O–N2 and dry O2-containing atmospheres were less than 6 μm after 20 min of oxidation, significantly smaller than those formed in atmospheres containing both oxygen and water vapour, and the scale structures developed in the three different scenarios were also very different. The scale formed in 17%H2O–N2 contained wustite only, the scale formed in dry O2-containing atmospheres comprised primarily hematite and some magnetite, and that in O2–H2O mixtures developed a multi-layered structure, generally with an innermost Fe2SiO4 + FeO layer, followed by FeO/Fe3O4/Fe2O3 layers towards the scale surface. A preformed oxide scale and the presence of 8%CO2 in the atmosphere had little effects on further steel oxidation. The mechanisms of forming different scale structures are discussed.

Failure during fabrication of clamps of Mn-alloyed steel for springs in heavy vehicles

Clamps or “U” bolts for springs in heavy trucks made of SAE 1552 C-Mn steel presented cracks during the fabrication process by flattening and bending. The cracks initiated in the external face of curves bended, where the tensile stress was maximum. The surface of cracking showed a large portion of brittle fracture by cleavage. The microstructure consisted of fine pearlite (major part), pro-eutectoid ferrite and traces of bainite. The bar used to fabricate the clamps were probably hot rolled and air cooled, resulting in a material with only 1.3% of uniform deformation in the tensile test. This study shows that the bars should have been quenched and tempered at around 600 °C, in order to provide higher workability to the flattening and bending processes, and improve mechanical properties for service.

Thermal characteristics of spring steels used in railway bogies

During the heat treatment of springs for railway bogies, phase transformations and oxidation occur and it is important to know transformation temperatures and oxidation rates to optimise the process. Oxidation and decarburisation can adversely affect the surface properties of steel when not limited to the bare minimum. The oxidation rates and material-specific phase transformation of the spring steels were evaluated by means of differential scanning calorimetry. Three spring steels with known mass were heated and cooled. The change in the corresponding heat flow was evaluated. The materials were also subjected to a regular spring steel heat treatment process in order to determine the relationship between oxidation rate and decarburisation. This allowed for the observation of phase transition and oxidation rate for each steel. The results of these investigations showed that there is a nonlinear relationship between oxidation and decarburisation. The three materials analysed showed distinct properties; therefore, understanding of the material characteristics is important. Material A showed a high oxidation rate with decreased decarburisation, whereas material B showed less oxidation and higher decarburisation due to higher silicon contents.

Reduced-Friction Centralizers Field-Tested for Ultraextended-Reach-Drilling Completions

This article, written by JPT Technology Editor Judy Feder, contains highlights of paper SPE 193342, “Development and Testing of Low-Friction-Coated Centralizers for Ultra-ERD Completions,” by Lei Wang, Jeffrey R. Bailey, SPE, Srinivasan Rajagopalan, Adnan Ozekcin, and Matthew Prim, ExxonMobil, prepared for the 2018 Abu Dhabi International Petroleum Exhibition and Conference, 12–15 November, Abu Dhabi. The paper has not been peer reviewed. Friction can pose major limitations on well length in ultraextended-reach-drilling (ultra-ERD) well completions. Centralizers coated with diamond-like carbon (DLC) coatings have been developed to provide operational advantages for these ultra-ERD applications. While drilling, pipe can be rotated to release friction, but in completion operations this may not be possible. Although pipe can be air-filled to provide buoyancy, there are many examples of screens and perforated pipe that cannot be floated. The complete paper documents the development, laboratory- and field testing, and lessons learned from a project to evaluate coated centralizers. Project Summary The project began with evaluation of currently available centralizers made of a hard material to support the thin, low-friction-coating layer. This led to selection of an inexpensive cast-iron centralizer that required machining and polishing before coating. Next, the project team selected the coating chemistry, layer hierarchy and functionality, and interlayer properties, applying knowledge from an artificial-lift application. Multiple coating compositions had previously been evaluated for friction and wear characteristics in block-on-ring laboratory tests.• Prototypes of the new centralizer with selected coatings were tested against commercially available centralizers in a laboratory environment to assess the friction-reduction potential of the coated centralizers. Tests were performed to measure the coefficient of friction (COF) of the coated centralizers against other types of uncoated tools made of cast iron, zinc alloy, pressed spring steel, and polymer under wet conditions in simulated cased and openhole conditions. The DLC-coated centralizers yielded the lowest COF overall when compared with existing tools. Following the promising laboratory results, the first field test was conducted in an onshore, unconventional horizontal well with high doglegs, for which the data showed very low friction over a 1,900-ft openhole interval. A second field trial was conducted in an offshore ERD well in a liner-running application. In this test, a stable low friction factor of 0.10 was observed over a 13,000-ft deviated section at 75°, measurably lower than the offset friction factor (FF) of 0.15. Both tests demonstrated intervals of very low friction; however, both experienced drag that might be the result of cuttings. To address this problem, a redesign based on a slicker centralizer profile has been prototyped. This new centralizer also requires less polishing and offers an inherently hard substrate that is beneficial to coating durability. Introduction An idea to use the low-friction properties of diamond-like surfaces in up-stream applications took root more than 10 years ago. Through various cycles of planning, testing, development, and field trials, the evaluation of multilayered thin-film coatings progressed from concept development to laboratory testing and, ultimately, field trials. One application to sucker rod couplings has progressed to early commercialization. This application primarily benefits from the wear resistance of the DLC coating and uses “counterface friendliness” by which the coating protects the counterface surface from wear.