Influence Of Preheating Research Articles

Influence of Preheating and Postweld Heat Treatment on the Structure and Strength of the Wire Frame Welded Joint Made of Spring Steel C62D

This article investigates the automatic welding of Ø4.5 mm high carbon steel wire frame. Using spring steel wire frame in car seat fabrication reduces its weight and helps to maintain rigidity. The thermal effect during the welding process can unacceptably deteriorate the mechanical properties of the material. It is proposed to use preheating and heat treatment to obtain a joint with required mechanical properties. To reduce of effect on entire product rigidity the thermal treatment was carried out locally in the zone of joining. Heating was carried out using a gas flame. Metallographic and microhardness measurements were used for the structural study. Mechanical properties were evaluated by static tension and free bending test. The recording of thermal cycles during the welding and heat treatment was carried out using chromel-alumel and tungsten-rhenium thermocouples.

Combustion of Ti–Al Mixtures: Influence of Preheating, Mechanical Activation, and Burning Mode

Combustion of Ti–Al Mixtures: Influence of Preheating, Mechanical Activation, and Burning Mode

Influence of pre-heating and ceramic thickness on physical properties of luting agents

The objective of this in vitro study was to evaluate the influence of ceramic thickness and pre-heating of luting agents on their physical properties. The materials RelyX Arc, RelyX Ultimate, RelyX Veneer, and Filtek Z350 Flow were handled at different temperatures (23°C or 54°C), inserted into matrix, and photoactivated through ceramic disks (0.75 mm or 1.5 mm). The following tests were performed ( n=8): degree of conversion, Knoop Hardness, cross-link density, water sorption, solubility, and ultimate tensile strength. Data were analyzed using three-way analysis of variance and Tukey's test (α=0.05). Regarding ceramic thickness, the thinnest ceramic resulted in higher values of Knoop Hardness ( p=0.027). The lowest temperature (23°C) resulted in a higher solubility ( p=0.0257), and water sorption ( p=0.0229) values. There was also statistical difference among the materials: RelyX Arc showed a higher degree of conversion and ultimate tensile strength, followed by RelyX Veneer, RelyX Ultimate, and Filtek Z350 Flow. For Knoop Hardness and cross-link density tests, RelyX Ultimate showed the highest values, followed by RelyX Arc, RelyX Veneer, and Filtek Z350 Flow. For water sorption and solubility, RelyX Veneer showed the highest values, followed by RelyX Arc, RelyX Ultimate, and Filtek Z350 Flow. Pre-heating interfered with water sorption and solubility, whereas ceramic thickness only affected Knoop Hardness; the physical properties of the materials are dependent on their composition.

The Influence of Preheat on Distortion and Fatigue Crack Propagation Rate of FCAW Weld in A 36 Steel Structure

Welding is one of the joining processes and it has been widely used, especially for steel welded structure in off-shore, pipeline or ship construction. Advantages of the welding joint are inexpensive, process joining can be done quickly and can produce light structure compared to other joining processes. One of welding techniques mostly used for joining steel construction is flux cored arc welding (FCAW). The commonly problems arise in this welding technique are distortion and low resistance of crack propagation. The aim of this study is to minimize distortion and to increase fatigue crack growth resistance of weld joint.In this research, FCAW welding was conducted without preheat and the other was preheated around welding area with temperature of 200 °C. Each of temperature welding process was measured using data acquisition. After completing the welding process, a sequence of experiment was conducted including chemical compositions, distortion and fatigue test. Result of this research shows that preheat temperature of 200 °C can decrease distortion and improve fatigue performance.

Formation And Distribution of Brittle Structures in Friction Stir Welding of AA 6061 To Copper. Influence of Preheat

Formation And Distribution of Brittle Structures in Friction Stir Welding of AA 6061 To Copper. Influence of Preheat

Influence of Preheating and Heat Treatment after Welding According to the EN 13445 and ASME Code on the Hardness Level of Welded Joints for the Pressure Vessel Plates

The paper deals with an analysis of preheating and heat treatment after welding and their influence on the final hardness level in case of welded jonits for common materials applied for manufacture of pressure vessel plates. During the welding process, the higher values of hardness and simultaneously decreasing of plasticity was observed and measured in the heat affected zone. Therefore, there was necessary to preheat the base material, or to apply the heat treatment after welding, or to suggest any combination of both mentioned ways. First of all, the groups of tested plates with required parameters were chosen for the application of the submerged arc welding method (according to ČSN EN ISO 4063), and preparation of samples for hardness measurement (ČSN EN ISO 6507) as the next step. The main goal of this experiment was to determine the hardness level for two fine grained steel grades after welding with the given parameters, as well as to adjust or to eliminiate the heat treatment process (preheating, post-heating), if they are not necessary.

The Influence of Pre-Heating on the Weldability of Pure Copper by FSW

This paper deals with an experimental investigation on the friction stir welding of pure copper. 4 mm thick copper plates have been welded in the butt joint configuration using a conical unthreaded tool, with and without preheating. An electrically heated backing plate has been employed to increase the initial temperature of the plates and to investigate the influence of pre-heating on the weld ability of the considered material. The welded joints have been analyzed by means of macroscopic and microscopic observations, microhardness measurements and tensile tests. Obtained outcomes suggest that more complex pin shape is needed to promote an adequate material flow without preheating.

The Influence on the Physical and Mechanical Properties of the Tread by Preheating of Raw Rubber

This paper using synchronous rotor mixer, had researched the influence of preheating of raw rubber on the physical and mechanical properties of the tread under the same fill factor, rotor speed, cooling water temperature, and the pressure on top of bolt. According to processing and analysis of the experimental data, we can conclude that: As the temperature of raw rubber increased, the physical and mechanical properties of the tread had changed.

Development of a new theory of thermal cutting processes 3. Influence of cutter’s front angle on the cutting temperature and influence of preheating of the blank on the cutting force

Within the framework already established, attention turns to the influence of the cutter’s front angle on the cutting temperature and to the influence of preheating of the blank on the cutting force.

On microstructure, hardness and wear behaviour of flame sprayed Co base alloy coating deposited on mild steel

In the present paper, the influence of preheat and post-spray heat treatment temperature on microstructure and adhesive wear behaviour of flame sprayed Co base hard facing alloy (EWAC 1006 EE) coatings on mild steel has been reported. Coatings were deposited by oxyacetylene thermal spraying torch. Thermal spraying of substrate was carried out at two preheat temperatures, i.e. 300 and 350°C. The post-spray heat treatment of the coatings was carried out at three different temperatures: 650, 750 and 850°C, for 2 h. Wear resistance of coatings was evaluated using ring on block wear system at 40 N normal load and 1 m s−1 sliding speed of ring. Hardness of coating, base metal and interface was tested using Vickers hardness testing machine. Optical studies of the microstructure of the substrate, interface and coating were carried out to investigate the influence of preheat and post-spray heat treatment temperatures. It has been found that an increase in post-spray heat treatment temperature enhances the hardness and wear resistance of the coating.

DTA Traces of Ammonium Perchlorate. Influence of Preheating and Aging

AbstractWhile 4 distinct endothermal processes are known to accompany the thermal decomposition of Ammonium Perchlorate (AP), the DTA thermograms show one endotherm corresponding to the structure transition at 240°C, and two exotherms. The different characteristic points of the DTA thermograms change with the thermal history of the sample and even with aging at ambient temperature. Periods of preheating at 150° lower the initial temperature of self‐heating at a later heating from about 300° for freshly recrystallised AP to about 210° after preheating for 4 days at 150°C. Heating‐cooling cycles above 200° (lower limit) up to 320° (upper limit) show for the first 2‐3 cycles the influence of the known “limited decomposition” of AP. On cooling there is a temperature delay in the structure transition cubic → orthorhombic, up to a constant limit of about 15°, and an apparent comminution of grains.