The Preheating Temperature Effects on the Residual Stresses of the Welded Rails Sections

2016 ◽  
pp. 169-178
Author(s):  
Oussama Bouazaoui ◽  
Abdelkrim Chouaf
Keyword(s):  
Residual Stresses ◽  
Temperature Effects ◽  
Preheating Temperature

scholarly journals Effect of Process Parameters and High-Temperature Preheating on Residual Stress and Relative Density of Ti6Al4V Processed by Selective Laser Melting

Materials ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 930 ◽  
Author(s):  
Martin Malý ◽  
Christian Höller ◽  
Mateusz Skalon ◽  
Benjamin Meier ◽  
Daniel Koutný ◽  
...  
Keyword(s):  
Residual Stress ◽  
High Temperature ◽  
Residual Stresses ◽  
Relative Density ◽  
Selective Laser Melting ◽  
Process Parameters ◽  
Stress Reduction ◽  
Laser Melting ◽  
Preheating Temperature ◽  
Laser Velocity

The aim of this study is to observe the effect of process parameters on residual stresses and relative density of Ti6Al4V samples produced by Selective Laser Melting. The investigated parameters were hatch laser power, hatch laser velocity, border laser velocity, high-temperature preheating and time delay. Residual stresses were evaluated by the bridge curvature method and relative density by the optical method. The effect of the observed process parameters was estimated by the design of experiment and surface response methods. It was found that for an effective residual stress reduction, the high preheating temperature was the most significant parameter. High preheating temperature also increased the relative density but caused changes in the chemical composition of Ti6Al4V unmelted powder. Chemical analysis proved that after one build job with high preheating temperature, oxygen and hydrogen content exceeded the ASTM B348 limits for Grade 5 titanium.

Residual stresses during surface cleaning with elastic abrasive wheels

2020 ◽  
pp. 54-61
Author(s):  
YU.V. Dimov ◽  
D.B. Podashev
Keyword(s):  
Experimental Data ◽  
Residual Stresses ◽  
Cutting Force ◽  
Temperature Effects ◽  
Cutting Speed ◽  
Surface Cleaning ◽  
Abrasive Wheel ◽  
Decisive Influence ◽  
Definition Of

An analytical definition of residual stresses during processing with elastic abrasive wheels (EAW) is proposed. It is established, that the rigidity of the EAW determines the decisive influence of force or temperature effects on residual stresses. The adequacy of the analytical definition is confirmed by experimental data. Keywords elastic abrasive wheel, residual stresses, cutting speed, deformation, cutting force, temperature. [email protected]

Residual Stresses During Coating Generation: Plasma Sprayed Alumina Coating on XC38 Measurements and Calculations

1998 ◽  
Author(s):  
A.C. Leger ◽  
A. Haddadi ◽  
B. Pateyron ◽  
G. Delluc ◽  
A. Grimaud ◽  
...  
Keyword(s):  
Residual Stresses ◽  
Time History ◽  
Alumina Coating ◽  
Thin Coatings ◽  
Preheating Temperature ◽  
History Of ◽  
Substrate Preheating ◽  
Plasma Sprayed ◽  
Thick Coatings ◽  
Temperature Time

Abstract A simplified ID model has been developed to calculate the temperature time history of alumina layering splats. The splats were obtained by plasma spraying alumina fused and crushed particles (- 45 + 22 µm). The model has shown that for more than 160-200 µm layered splats the solidification time is over 7-10 µs, When spraying thin passes (ep < 15 µm) each splat cools down to substrate preheating temperature before next splat impacts. On the contrary for thick passes (ep = 60 or 180 µm), after depositing a certain thickness (between 160 and 200 µm) depending on spraying conditions, the temperature of the splats never drops below 800-900 K (mean splat temperature). In this case nucleation occurs after flattening is completed. Such conditions allow a columnar growth through the layered splats of each pass and successive passes. The study of the corresponding stresses (quenching σq and expansion mismatch) generated when spraying alumina on XC38 sheet was measured by following continuously the bending of a beam. The comparison of the measurements with the results of a ID model developed by Tsui and Clyne has allowed to calculate the coating Young's modulus Ed and the residual stresses difference at the interface. For thin coatings σq and Ed increase with preheating temperature. For thick coatings the values of Ed and σq are lower than the highest ones of thin coatings. This is probably due to stress relaxation by cracks propagation, the quenching and expansion mismatch stresses increasing with the increasing mean splat temperature.

The Influence of Material Models on Finite Element Simulation of Machining

2004 ◽  
Vol 126 (4) ◽  
pp. 849-857 ◽  
Author(s):  
Jing Shi ◽  
C. Richard Liu
Keyword(s):  
Finite Element ◽  
Residual Stresses ◽  
Power Law ◽  
Cutting Forces ◽  
Temperature Effects ◽  
Test Results ◽  
Material Models ◽  
Orthogonal Machining ◽  
Element Simulation ◽  
Selection Of

In literature, four models incorporating strain rate and temperature effects are able to generalize material test results of HY-100 steel. This study compares the four models, namely, Litonski-Batra, power law, Johnson-Cook, and Bodner-Partom, in finite element modeling of orthogonal machining of this material. Consistency is found in cutting forces, as well as in stress and temperature patterns in all but the Litonski-Batra model. However, the predicted chip curls are inconsistent among the four models. Furthermore, the predicted residual stresses are substantially sensitive to the selection of material models. The magnitudes, and even the sign of the residual stresses in machined surfaces, vary with different models.

Analysis on Residue Stresses in Coating of Thin-Wall Parts by Plasma Spraying

2011 ◽  
Vol 391-392 ◽  
pp. 654-660
Author(s):  
Li Ping Niu ◽  
Ting An Zhang ◽  
Ji Cheng He ◽  
Zhi He Dou
Keyword(s):  
Mathematical Method ◽  
Thermal Expansion ◽  
Residual Stresses ◽  
Plasma Spraying ◽  
Experimental Testing ◽  
Processing Parameters ◽  
Thin Wall ◽  
Preheating Temperature ◽  
Substrate Preheating ◽  
Mathematical Techniques

Residual stresses are determined by different materials and processing parameters so that it is hard to systematically carry on the experimental testing, and it also spends a plenty of time and running costs. Therefore, it is necessary to estimate the residual stresses by mathematical techniques. In this paper, a mathematical method is proposed, and the calculating results are compared with the testing results of alumina and W coatings on various matrixes (process: plasma spraying) that are highly consistent. The calculating results show that the thermal expansion coefficient, substrate preheating temperature and thickness of coating have significant effects on the residual stresses.

Optimized Conditions for Tensile Residual Stress Reducing Weld Using Water-Shower Cooling

2003 ◽  
Author(s):  
Nobuyoshi Yanagida ◽  
Kunio Enomoto ◽  
Hideya Anzai
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Residual Stresses ◽  
Heat Input ◽  
Fem Analysis ◽  
Tensile Residual Stress ◽  
Input Quantity ◽  
Preheating Temperature ◽  
Optimized Conditions

To reduce tensile residual stress in a welded region, we developed a new cooling method that applies a water shower behind the welding torch. When this method is applied to the welding of austenitic stainless-steel, the welding and cooling conditions mainly determine how much the residual stress can be reduced. To optimize these conditions, we first used FEM to determine the effects of preheating temperature, heat input quantity, and water-shower area on the residual stress, and found that, to decrease tensile residual stress, preheating temperature should be high, heat input low, and the water-shower large. To confirm the effectiveness of these optimized conditions, residual stresses under optimized or non-optimized conditions were experimentally measured. It was found that the residual stresses were tensile under the non-optimized conditions, but compressive under the optimized ones. These measurements agree well with the FEM analysis. It can therefore be concluded that the optimized conditions are valid and appropriate for reducing residual stress in an austenitic stainless-steel weld.

Salt, Cryoprotectants and Preheating Temperature Effects on Surimi-like Material from Beef or Pork

1996 ◽  
Vol 61 (4) ◽  
pp. 790-795 ◽  
Author(s):  
S. PARK ◽  
M.S. BREWER ◽  
F.K. McKEITH ◽  
P.J. BECHTEL ◽  
J. NOVAKOFSKI
Keyword(s):  
Temperature Effects ◽  
Preheating Temperature

scholarly journals Investigation of Performance and Residual Stress Generation of AlSi10Mg Processed by Selective Laser Melting

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Lianfeng Wang ◽  
Xiaohui Jiang ◽  
Yihong Zhu ◽  
Zishan Ding ◽  
Xiaogang Zhu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Residual Stresses ◽  
Selective Laser Melting ◽  
Tilt Angle ◽  
Side Surface ◽  
Stress Generation ◽  
Laser Melting ◽  
Scanning Strategy ◽  
Preheating Temperature

During the selective laser melting (SLM) process, the scanned layers are subjected to rapid thermal cycles. By working on the mechanical properties, residual stress, and microstructure, the high-temperature gradients can have significant effect on the proper functioning and the structural integrity of built parts. This work presents a comprehensive study on the scanning path type and preheating temperature for AlSi10Mg alloy during SLM. According to the results, SLM AlSi10Mg parts fabricated in chessboard scanning strategy have higher mechanical properties or at least comparable to the parts fabricated in uniformity scanning strategy. In the SLM processing, the residual stress in different parts of the specimen varies with temperature gradient, and the residual stress at the edge of the specimen is obviously larger than that at the center. Under the chessboard scanning and preheating temperature 160°C, the residual stress in each direction of the specimens reaches the minimum. Under different forming processes, the morphology of the microstructure is obviously different. With the increase of preheating temperature, the molten pool in the side surface is obviously elongated and highly unevenly distributed. From the coupling relationship between the residual stress and microstructure, it can be found that the microstructure of top surface is affected by residual stresses σx and σy. But the side surface is mainly governed by residual stress σy; moreover, the greater the residual stress, the more obvious the grain tilt. In the XY and XZ surfaces, the scanning strategy has little influence on the tilt angle of the grain. But, the tilt angle and morphology of the microstructure are obviously affected by the preheating temperature. The results show that the residual stresses can effectively change the properties of the materials under the combined influence of scanning strategy and preheating temperature.

scholarly journals Considerations for Measuring Residual Stresses in Driven Piles with Vibrating Wire Strain Gauges

2021 ◽  
Author(s):  
James Ryan Bartz ◽  
James A. Blatz
Keyword(s):  
Residual Stresses ◽  
Temperature Effects ◽  
Strain Gauges ◽  
Pile Driving ◽  
Driven Piles ◽  
Vibrating Wire ◽  
Data Logger ◽  
Temperature Changes ◽  
Wire Strain ◽  
Below Ground

Vibrating wire strain gauges are often the preferred technology for measuring strain in driven piles. However, measuring the residual strain after pile driving is challenging to accomplish using vibrating wire gauges. The driving process can cause a shift in the no-load reading from a relaxation of locked-in manufacturing strains in the pile or relaxation of the gauge wire tension. Also, there are temperature effects from installing piles below ground. A test pile program was developed using driven steel H-piles instrumented with vibrating wire strain gauges. The piles were subjected to dynamic forces by striking against a steel plate in attempt to relax the locked-in manufacturing strain prior to installation. The strain gauges and thermistors were connected to a data logger during pile driving to record strain and temperature changes following installation. It was observed that applying a dynamic impact to the piles prior to installation resulted in a shift of 0 to 5 microstrain. Temperature effects from installing the piles in cooler ground resulted in a shifts of strain in excess of 60 microstrain in some strain gauges. It is concluded that temperature induced shifts to strain must be measured following pile driving to interpret residual stresses.

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