Cam Plastometer Research Articles

Rheological Properties and Microstructure of PH1 Stainless Steel Produced by Selective Laser Melting

The present study is focused on rheological properties of PH1 stainless steel, produced by selective laser melting (SLM), at temperatures of hot deformation, with the aim to investigate the dependence of strain resistance on temperature and strain degree. The tests of cylindrical specimens, made of PH1 stainless steel, were carried out using a cam plastometer in temperature range 700 – 1200 °C at a strain rate ξ equal to 1 s-1 up to strain degree e equal to 0.8 – 1.2. The paper presents the results of investigation of initial microstructure, microhardness measurement and flow curves of PH1 steel, produced by SLM method. The flow curves of PH1 steel produced by SLM can be used in the development of new methods of manufacturing the metallic parts by additive technologies with the use of deformation post-processing.

Rheological Properties and Microstructure of AlSi10Mg Aluminum Alloy produced by Selective Laser Melting

The present study is focused on rheological properties of AlSi10Mg aluminium alloy produced by selective laser melting (SLM) at temperatures of hot deformation with the aim to investigate the dependence of strain resistance on temperature, strain rate and strain degree. As-build cylindrical specimens made of AlSi10Mg aluminium alloy was examined on a cam plastometer in temperature range 20 – 500 °C, at strain rate ξ equal to 1, 10 s-1 up to strain degree e equal to 1.2. The paper presents results of study of initial microstructure, microhardness measurement and flow curves of AlSi10Mg alloy produced by SLM. The flow curves of AlSi10Mg alloy produced by SLM can be used in the computer simulation and development of new manufacturing methods of the metallic parts by additive technologies with the use of deformation post-treatment.

Plastometric Simulation of the Hot Rolling Process of Al/B4C Powder Composite

.

炭素繊維強化軟質エポキシ樹脂の衝撃曲げ特性評価

In the present study, quasi-static and dynamic bending behavior of CFRP (carbon fiber reinforced plastics) with soft epoxy matrix was investigated. CFRPs were fabricated with the soft epoxy matrix and a standard carbon woven fabrics. The carbon woven fabrics of 5 layers were laminated to be quasi-isotropic. The impact three-point bend testing machine based on the split Hopkinson pressure-bar technique was developed. The bending tests were performed by a universal testing machine for low deflection velocities, a cam plastometer for middle ones and the impact testing machine for high ones. The experiments reveal that the bending modulus of the CFRPs strongly depends on the deflection velocity.

Investigation into the deformation resistance of polycrystalline iridium

Rheological properties of polycrystalline iridium of I 99.9 grade are investigated in order to construct the dependence of deformation resistance on studied factors (strain ratio, rate, and temperature). The tests of cylindrical samples made of iridium are performed using a cam plastometer in temperature range t = 900–1400°C at strain rates ξ = 0.2 and 20 s–1, as well as at t = 800–1400°C and ξ = 2 s–1 using the upsetting method at a strain rate up to 0.8. The results of investigations can be used to develop the pressure treatment of iridium wares at large plastic strains and in a broad range of thermomechanical parameters.

Investigation into the Deformation Resistance of Polycrystalline Iridium

Rheological properties of polycrystalline iridium of I 99.9 brand are investigated in order to construct the dependence of deformation resistance on studied factors (strain ratio, rate, and temperature). The tests of cylindrical samples made of iridium are performed using a cam plastometer in temperature range t = 900÷1400 °C at strain rates ξ = 0,2 and 20 s–1 as well as at t = 800÷1400 °C and ξ = 2 s–1 using the upsetting method at a strain rate up to 0,8. The results of investigations can be used to develop the pressure treatment of iridium wares at large plastic strains and in a broad range of thermomechanical parameters.

Dynamic properties of high structural integrity auxetic open cell foam

This paper illustrates various dynamic characteristics of open cell compliant polyurethanefoam with auxetic (negative Poisson’s ratio) behaviour. The foam is obtained fromoff-the-shelf open cell polyurethane grey foam with a manufacturing process based onmechanical deformation on a mould in a temperature-controlled oven. The Poisson’s ratiois measured with an image processing technique based on edge detection with waveletmethods. Foam samples have been tested in a viscoelastic analyser tensile test machine todetermine the Young’s modulus and loss factor for small dynamic strains. The samesamples have also been tested in an acoustic impedance tube to measure acousticabsorption and specific acoustic resistance and reactance with a transmissibilitytechnique. Another set of tests has been set up on a cam plastometer machine forconstant strain rate dynamic crushing analysis. All the tests have been carried outon auxetic and normal foam samples to provide a comparison between the twotypes of cellular solids. The results from the experimental tests are discussedand interpreted using microstructure models for cellular materials existing in theliterature. The negative Poisson’s ratio foam presented in this paper shows an overallsuperiority regarding damping and acoustic properties compared to the originalconventional foam. Its dynamic crushing performance is also significantly superior to thenormal foam, suggesting a possible use in structural integrity compliant elements.

Constitutive Relationships for Hot Deformation of A Carbon Steel: A Comparison Study of Compression Tests and Torsion Tests

A 0.34% carbon steel was subjected to hot working (800–1100°C) by Gleeble compression to 0.7 strain at strain rates of 0.1–8 s−1, cam plastometer compression to 0.4 strain at strain rates of 3.5–10...

The thermal and metallurgical state of steel strip during hot rolling: Part II. Factors influencing rolling loads

Traditional models for computing roll forces during hot rolling generally ignore the steep thermal gradients set up in the through-thickness direction due to roll chilling and deformation heat. In this paper, Alexander’s model has been modified to account for the effect of thermal gradients on roll forces. Flow stress data have been obtained by conducting tests on a cam plastometer and a Gleeble 1500 for a 0.05 pct carbon, a 0.34 pct carbon, and a 0.07 pct carbon with 0.024 pct niobium steel for temperatures and strain rates attained in each of the stands on Stelco’s Lake Erie Works (LEW) hot-strip mill. The hyperbolic sine equation has been shown to fit the data and is capable of predicting flow stress over a range of temperatures and strain rates. Simulations of the industrial operation have been conducted on the pilot mill at CANMET, and it has been shown by comparing predicted and measured roll forces that the friction coefficient is reduced from 0.3 to ∼R 0.35 to 0.25 in the presence of a lubricant. It has also been shown that incorporating the steep thermal gradients in the roll-bite zone increases predicted roll forces by 6 to ∼R 10 pct over the values computed based on centerline temperatures. The model has been validated also by comparing predictions with roll forces measured on the industrial mill.

Effects of thermomechanical processing on the microstructure and mechanical properties of a Ti-V-N steel

Based on studies of austenite deformation behavior and continuous-cooling-transformation behavior of a Ti-V microalloyed steel by cam plastometer and quench-deformation dilatometer, respectively, plate rolling schedules were designed to produce (i) recrystallized austenite, (ii) unrecrystallized austenite, (iii) deformed ferrite + unrecrystallized austenite. The effects of austenite condition and cooling rate on the final microstructure and mechanical properties were investigated. To rationalize the variation in final ferrite grain size with different thermomechanical processing schedules, it is necessary to consider the kinetics of ferrite grain growth in addition to the density of ferrite nucleation sites. The benefit of dilatometer studies in determining the optimum deformation schedule and cooling rate for a given steel is domonstrated. A wide range of tensile and impact properties results from the different microstructures studied. Yield strength is increased by increasing the amount of deformed ferrite, bainite, or martensite, and by decreasing the ferrite grain size. Impact toughness is most strongly influenced by ferrite grain size and occurrence of rolling plane delaminations.

The high temperature and high strain-rate behaviour of a plain carbon and an HSLA steel

The high temperature, high strain-rate stress-strain curves of a plain carbon and an HSLA steel have been determined using a cam plastometer. The cylindrical samples were deformed in compression at constant true strain rates of 2, 20, and 120 s −1 and at temperatures of 900, 1000, and 1100°C. The effects of temperature and strain rate on the flow stress at a particular strain can be represented by the following expressions: exp(βσ)= A 1 ϵ ̇ exp(Q/RT) [ sinh (ασ)] n = A 2 ϵ ̇ exp(Q/RT) The constants of these equations have been determined empirically. A modified Ludwik equation of the form: σ=b+cϵ 0.4+dϵ 0.8+eϵ 1.2 has been used to represent stress as a function of strain. It was found that a very good representation of the data for the plain carbon steel, over a wide range of temperatures and strain rates, can be obtained by using these two types of equations sequentially. Attempts to use this same approach for the HSLA steel failed because of a behaviour of an athermal type occurring between 900 and 1000°C.

アルミ熱延計算機制御用数式モデル

Methematical models for estimating rolling force P, rolling torque G and forward slip f were developed. These models consist of equations for calculating rolling force function QP, rolling torque function QG, forward slip f, mean flow stress Kfm, temperature of rolled material T and friction coefficient, μ. QP, QG and f equations are derived by the multiple regression analysis of calculated values of Orowan's exact theory, Kfm equation is based on the empirical expression of the experimental data of cam plastometer and besides corrected by the correction parameter. T equation is derived theoretically considering temperature change during air cooling, spray cooling and roll gap. Heat transfer coefficients decided in the former study are used. The values of μ and correction parameter of Kfm are decided simultaneously by substituting measured values of f and P into the f and P models and solving them. Almost satisfactory accuracy is achieved in estimating P, G and f. Improving the accuracy is expected by the use of (coil to coil) plus (lot to lot) adaptive control method.

Frictional effects on flow stress determination at high temperatures and strain rates

It has been reported recently that the average die pressure as measured during the initial compression of non-lubricated cylinders was less than 5% greater than that for lubricated samples, when the final diameter-to-height ratio is less than 2. These tests were carried out at room temperature and low strain-rates. To determine whether these results occur at high temperature and high strain-rates, cylinders of hot-rolled low-carbon steel were upset under lubricated and non-lubricated conditions. The steel samples were deformed by a cam plastometer at constant true strain-rates of 2.0, 20.0 and 140.0 s −1. The results clearly show that the average die pressure for lubricated and non-lubricated samples are, within experimental accuracy, equal. Further testing demonstrated that the average die pressure does not depend on sample geometry for cylinders with initial aspect ratios of 0.5, 0.65 and 0.85, deformed to a true strain of 0.7. For the range of aspects ratios examined, it can be concluded that a correction for friction in the calculation of flow stress is unnecessary.

純アルミニウムおよびアルミニウム合金の変形抵抗の数式モデル

The resistance to deformation of commercial pure aluminum and aluminum alloys has been investigated experimentally by using a cam plastometer. Materials tested in this peper are A1070, A1050, A1100, A3003, A5052, Al-1.2%Cu (KD) alloy. The deformation resistance-strain curves of those materials have been determined over a temparature range 300500°Ç, strain rate 1.012.0 sec<-1>. The deformation resistance Kf was related to the true strain ε and the strain rate ε through a power law, i. e., Kf = Knεn and Kf = Kmεm. The relation between the deformation resistance Kf, temperature T, strain ε, strain rate ε can be expressed not by the usual form; Kf = K0εnεme<A/T> but by the form; Kf = (a+b/T+c/T2)εnεm, where a, b, c, n, m are constants dependent only on the material.

Constant true strain rate compression: The cam plastometer

Abstract A cam plastometer is a constant true strain rate compression testing machine used in studying the hot-working behaviour of metals. The reasons for the constant true strain rate testing procedure are discussed. The recently completed machine at the Mines Branch, Ottawa, Canada is described in detail This new machine has advanced the technology of cam plastometers mainly in the ease of testing and machine controls and also in the accuracy of the test results. Tests can be conducted at constant strain rates between 0.1 and 200 per second. The maximum load at all strain rates is 0.45 MN (100,000 lb). Several true stress-strain curves obtained from this machine are presented for an Al-Cu alloy. Resume Le plastometre a came est un appareil permettant d' etudier le comportement a chaud des materiaux a taux constant de deformation rationnelle. Les raisons pour lesquelles on recherche un tel taux sont presentees. Le plastometre qui vient d'etre installe a la Direction des Mines a Ottawa est decrit en deta...

Texture and mechanical properties of 6063 alloys extruded by a cam plastometer

Texture and mechanical properties of 6063 alloys extruded by a cam plastometer

訂正

訂正

Cam plastometer data acquisition system

A high-speed system was designed and built to acquire time, temperature and load data from experiments in the cam plastometer. The cam plastometer is a mechanical testing machine which measures a fundamental property of non-brittle materials, namely their resistance to compressive deformation, during such deformation at constant true-strain rates. Early versions of the machine operated at comparatively low strain rates. The machine was constantly improved until it now operates over a wide range of true (logarithmic) strain rates, from 0.05 to greater than 200 s-1. This range of rates requires the versatile, high-speed data acquisition system described in this paper. Operation of the cam plastometer is briefly described; then the sequence of acquiring data during an experiment, of storing these data in a ferrite-core memory, and of subsequently retrieving them for computer processing is given. Operation of the circuits which control input to, and output from, the memory is set forth in detail.

Mechanical testing machine stiffness: Part I—Theory and calculations

The importance of elastic interaction between specimen and testing machine in many mechanical property tests is discussed, and drawbacks to the usual methods of calculating machine stiffness are considered. Two expressions are proposed for calculating the effective testing machine stiffness, which is actually a composite stiffness including machine, grips or platens, load cell, insulation and lubricant. This stiffness is calculated from data acquired during compression tests in the LASL Cam Plastometer. The derived expressions can be adapted to calculate stiffness of many types of programmed testing machines; and they are so adapted to apply to both tensile and compressive testing in constant crosshead speed machines. Stiffnesses were calculated for over 200 tests in the LASL Cam Plastometer, and for a few tests in compression and a few in tension in constant crosshead speed machines. From the results of these calculations it was concluded that machine stiffness is a variable quantity which generally tends to increase as the applied load increases. Finally, because under sensibly identical experimental conditions there are large differences in calculated stiffnesses, it was concluded that it is necessary to perform such calculations for each mechanical test. Only by so doing can the specimen-machine interaction be properly taken into account when calculating stress-strain curves from load-time or load-displacement data.

Microstructures of aluminum compressed at various rates and temperatures

Specimens of 1100 aluminum were compressed uniformly to a logarithmic strain of 0.7 (50 pct reduction) at constant true strain rates in a Cam Plastometer. Tests were conducted at strain rates between 220 and 0.1 sec−1 and between 500°C and 20°C. Exmination of the microstructures by electron microscopy indicated that the deformed structure consisted of dislocation cells or subgrains. As the temperature of testing was raised or the strain rate lowered, the resulting subgrains were larger, and the dislocations in the subboundaries were arranged in more orderly arrays. The cell sizes are related quantitatively to the flow parameters. The dependence of dynamic recovery on temperature and strain rate is compared to the dependence observed in extrusion of a similar alloy. At high strain rates at 400° and 500°C, partial recrystallization occurred while the specimens were cooling to room temperature.