Different welding methods are different welding processes. Welding electrode welding process is based mainly on pieces of the material, grade, chemical composition, structure type welds, welding performance requirements to determine. First, to determine the welding method, such as hand arc welding, submerged arc welding, TIG welding, MIG welding, etc., many types of welding methods can only be selected according to specific circumstances. Determine the welding method, and then the development of welding parameters, welding parameters of different types, such as hand arc include: electrode type (or brand), diameter, current, voltage, welding power source type, polarity connection, welding layers, number, test methods and so on. Atlas Welding Welding of carbon steel points ⑴ beneficial to reduce the warm-up warm-carbon steel heat-affected zone in the maximum hardness and prevent cold cracking, which is the main carbon steel welding process measures, but also to improve the joint warm-up plastic, reducing the residual stress after welding. Typically, 35 and 45 steel preheating temperature 150 ~ 250 ℃ or higher in carbon content of the thickness and stiffness due to large cracks tend to large, pre-heating temperature can be increased to 250 ~ 400 ℃. If the weldment is too large when the overall difficulties preheating, preheating can be local, local preheating of the heating for the welding of both sides of the range of 150 ~ 200mm. ⑵ electrode preferred alkaline conditions permit electrode. ⑶ groove welds as the U-shaped opening into the welding groove type. If the casting defect, shovel dug the groove shape should be smooth, and its aim is to reduce the base metal into the weld metal in the melting ratio to reduce the carbon content of the weld to prevent cracks. ⑷ welding parameters due to the first layer of base metal melted in the proportion of weld metal up to 30%, so the first layer of weld, should maximize the use of small current, the slow welding speed, to reduce the base metal melting deep. ⑸ PWHT best butt welding fittings immediately after the stress relief heat treatment, especially for the large thickness of the weldment, high rigid structure and the harsh conditions (dynamic load or impact load) weldment work and even more so. Stress relief tempering temperature 600 ~ 650 ℃. If post-weld stress relief heat treatment can not be carried out immediately after the heat treatment. Basic knowledge of welding technology welding by heat, pressure, or both, so that the two combining atoms workpiece processing technology and connectivity options. Welding is widely used, both for the metal, also used for non-metallic. Metal welding method has more than 40, divided into welding, pressure welding and brazing three categories. Welding is the welding process will be heated to melt the workpiece interface, the state, without pressure to complete the welding method. When welding, heat welding the two parts will be rapid heating and melting interfaces, the formation of molten pool. Move forward with the heat bath, which cooled to form a continuous weld connecting the two parts into one. In the welding process, if the atmosphere in direct contact with the hot bath, oxygen will be oxidized in the atmosphere and various alloys of metal elements. Atmospheric nitrogen, water vapor, etc. into the pool, but also the subsequent cooling process in the formation of pores in the weld, slag, cracks and other defects, deterioration of weld quality and performance. In order to improve the welding quality, it developed a variety of protection methods. For example, gas shielded arc welding is to use argon, carbon dioxide and other gases isolated from the atmosphere to protect the welding arc and weld pool rate; Another example is the steel welding, electrode coating in the addition of the oxygen affinity of titanium powder deoxy large, can protect the electrode in the beneficial elements manganese, silicon and into the pool from oxidation, after cooling to obtain high-quality welds. Bonding in the pressure conditions, so that the two parts between atoms in the solid state combination to achieve, also known as solid-state welding. Pressure welding process is commonly used in resistance welding, when the current through the two parts of the connector, the Department is very large temperature increase due to resistance, when heated to a plastic state, under pressure in the axial connection to become one. A variety of bonding methods are common characteristics of pressure in the welding process without additional filler material. Most diffusion bonding methods such as welding, high frequency welding, cold welding that there was no melting process, and thus not as useful as alloying elements fusion burning, invasive and harmful elements in the weld problems, which simplifies the welding process, but also welding safety and health conditions improved. At the same time lower the heating temperature than welding, heating time is short, so a small heat affected zone. Many difficult to melt welding materials, welding and can often be pressed into the base metal with the same intensity and quality of joints. Brazing is the use of low melting point than the piece of metal materials for the solder, and solder the workpiece is heated to above the solder melting point, melting point lower than the temperature of the workpiece, the workpiece using liquid solder, filling the gap with the workpiece to achieve the interface Interdiffusion of atoms in order to achieve welding methods. Welded connections are formed when the two are connected body known as the weld seam. Both sides of the welding seam welding heat will be the role of organizational and performance changes occur, this area is called the heat affected zone. Welding due to the workpiece material welding material, welding current and so different, after welding, weld and heat affected zone in the possible overheating, embrittlement, hardening or softening, also weldment performance degradation, deterioration of weldability. This need to adjust the welding conditions, welding parts before welding interface preheating, welding, heat and post weld heat treatment can improve the welding quality of welds. In addition, welding is a rapid local heating and cooling process, welding zone due to the binding around the body parts can not be free expansion and contraction, after cooling in the welding parts welding stress and deformation arises. Important products are required after welding to eliminate residual stresses, welding distortion correction. Modern welding technology has been able to weld the inside and outside the defect-free, mechanical properties equal to or higher than the body of the weld to be connected. Welded body position in space, called the welded joints with each other, except the strength of joints affected by the weld quality, but also its geometric shape, size, force and conditions of work and so on. The basic form of butt joints, lap, T-connection (positive transfer) and fillet and so on. Cross-section of butt joint weld shape, determined to be welded before welding, the thickness of the body and the two sides of the groove then. Welding thick steel plates, in order to access penetration in the edges of various shapes out of the groove in order to more easily into the electrode or wire. Groove in the form of single-sided welding of the welding groove and the sides of the groove. Choice of groove, in addition to ensuring penetration welding should be considered outside the convenience, less filler metal, welding deformation is small and low processing costs groove factor. Docking of two steel plates of different thickness, in order to avoid drastic changes in cross-section caused by severe stress concentration, often to the gradual thinning thick edge to reach the two connected edges of equal thickness. Butt joint static strength and fatigue strength higher than other joints. In alternating, shock loads or work in low-temperature high-pressure vessel join, often preferred by butt joint welding. Before welding the lap joint preparation is simple, convenient assembly, welding deformation and residual stress is smaller, and therefore unimportant in the site installation of the structure of joints and is often used. In general, the lap joint is not suitable in alternating load, corrosion medium, high or low temperature conditions. Use of T-joints and corner joints is usually due to structural needs. T-connector on the lack of penetration of the fillet weld characteristics and the work of the fillet weld lap joint similar. When the weld perpendicular to the external force becomes positive when the fillet weld, then weld surface shape can cause varying degrees of stress concentration; penetration of the fillet weld and butt joint force similar to the situation. Angle connector carrying capacity is low, generally not used alone, only in the penetration, or when the fillet weld both inside and outside improvements, multi-shaped structure for the closed corner. Riveting welding products(Welding Flux), castings and forgings, light weight, it can reduce the transport weight and save energy. Welding sealing, suitable for manufacturing various types of containers. Joint development process, so that welding and forging, casting the combination can be made large, the economy and reasonable welding structure and forge welding structure, economic efficiency is very high. Effective use of welding process used materials, welded structure can be different in different parts of the performance of the material, give full play to the strengths of various materials, to achieve economic, high quality. Welding has become an indispensable in modern industry, but also an increasingly important processing method. In the modern metal processing, welding to casting, forging technology development later, but the development fast. The weight of welded structure steel production accounts for about 45% of the structure of aluminum and aluminum alloy welding proportion is increasing. The future of welding technology, on the one hand the development of new welding method, welding equipment and welding materials, to further improve the welding quality and safety and reliability, such as the improvement of existing electric arc, plasma arc, electron beam, laser welding energy; the use of electronic technology and control technology to improve process performance arc, the arc developed lightweight and reliable tracking method. On the other hand to raise the level of mechanization and automation weld, such as welders to achieve process control, digital control; developed from the preparatory process, welding process automation to quality control all the special welder(Welding Rods); in the automatic welding production line, marketing, expansion of the welding NC robot and welding robot, welding can increase the level of production, improve health and safety conditions of welding.
Low carbon steel is lower than 0.25% carbon content. The resistivity is moderate, welding power is not needed but welding wire ; plastic temperature zone wide, easy access to the required plastic deformation of the pressure of having to use large electrodes; carbon and trace element content is low, no high melting point oxides, generally do not produce Quenching or inclusions; crystallization temperature range of narrow, high temperature strength, low thermal expansion coefficient, and therefore tend to a small crack. Such steel has good weldability, the welding current, welding rods
force and power and time parameters have greater adjustment range.
Steel has good weldability, the welding current, electrode force and power and time parameters have greater adjustment range.