Determining and solving the problems of welding wires produced by cold drawing method

For centuries, forge welding is the only welding method that used by mankind until nowadays welding technology invented. It is a crude and cumbersome blacksmith-type operation in which heated metals were pounded or rammed together until they bonded. The invention of forge welding is still an unknown phenomena. A few implements of iron or steel can survive corrosion over hundreds of years, so there remains little direct evidence of early forge welding method. By the time of Renaissance, technology and science has shown tremendous changes and craftsmen were highly skilled in forge welding. This came up with new methods for forge welding. New heating chambers, new technics and devices have been developed for pounding the metals. Thanks to this changes, forge welding has been a more effective technic and gave opportunities for pounding of bigger metal parts. There is evidence that, Professor G. Lichtenberg may invent the electric arc welding technology in 1782. Although, Sir Humphrey Davy is the first scientist who created the arc by using electric. In 1801, Davy discovered that an arc could be created with a high voltage electric circuit by bringing the two opposite poles together. This arc that he created had a bright light, could heat the metal and its length could be set in different limits. In the light of this inventions, Benardos and Olszewski are invented the most close electric arc welding in compare of nowadays technology. They used an apparatus which contains a carbon electrode and two opposite poles that attached to the metals and the electrode. A voltaic arc is formed by the approach of carbon electrode to the metal surface and welding start with this arc. Length and penetration of welding seam could be set. John C. Lincoln is the most important scientists in the using of metal inert gas (MIG) welding and MIG welding wire technology which is the main topic of this thesis. Lincoln used the CO2 gas as a protective atmosphere in welding. So, Lincoln cutted of the connection between welding seam and out atmosphere and this lead to better and safer welding seams. By the World War I and World War II, welding technology has tremendous changes. The need for large transport ships, safe planes, submarines and tanks forced mankind to improve the welding technology. Wire technologies and wire drawing lasts to ancient history. According to findings and evidences, gold is the most important and oldest known metal used as wire. In xxii the early methods of gold wire, in 3000 BC, Egyptians cut strips from hammered foils and then drew folded strips though stone dies as the initial step in wire making. Natural stones are the first known drawing dies. Craftsmen have been pulling the foils through dies and gave the gold a wire shape. There are also interesting references to wire history. According to Homer's Odyssey; Persians were drawing 0,55 mm. bronze wire with iron draw plates, implying that they may have understood the concepts of multiple passes and interpass annealing. A document written in Paris around 1270 implies the importance of wire drawing and notes interesting rules about craftsmen. For example, document notes that; the wire drawer may have as many apprentices and servants as he wishes and may work nights as much as he pleases. The wire drawer need pay no taxes on anything relating to his trade which he buys or sells in Paris. Nuremberg in Germany, was the capital of wire drawing technology in Renaissance Era. Developments in wire drawing technology are attributed to Rudolph von Nuremberg. Previous to him, only source for drawing the wire was man power, but he used the water power as a source and made the drawing easier for craftsmen. He is also first men to use the camshaft-driven draw benches. As the years passed, craftsmen understood the importance of different die materials such as iron and steel plates. So, new materials have used as drawing die. Most important examples are iron, steel and wolfram carbide dies. The wolfram carbide is the last and most used die nowadays technology. It has a good wear resistance, effective, easy to product and medium benefit-cost ratio. In the early technology, tallow and animal oil has been used as lubricants. By the using of iron dies, the importance of lubricants and lubrication has been seen. Scientists and craftsmen investigated different lubricant types. Natural clay and iron compounds can be seen as first materials for lubrication. Nowadays technology, there are 2 types of lubricants. These are dry drawing lubricants and wet drawing lubricants. Most important and widely used dry drawing lubricants are calcium stearate and sodium stearate. Industrial oils, water soluble oils and pure oils are the important wet drawing lubricants. In this thesis; the problems which seen through production of cold drawn MIG welding wires investigated. Within this scope, mechanical tests, chemical analysis, metallographic investigations and scanning electron microscope investigations applied on specimens of 3Si1 and 4Si1 raw materials which have supplied from 4 different suppliers. Two of these suppliers are from Germany and two from Turkey. Suppliers named as Supplier A, Supplier B, Supplier C and Supplier D. Inclusions and microstructure investigated by scanning electron microscope and metallographic microscope. In total; 46 specimens for microstructure and 65 specimens for inclusions has been investigated. Microstructures and inclusions classified by the production methods, by types and by dimensions. Hazardous and nonhazardous inclusions determined and classified. Wire breakages, have been observed in a welding wire and welding electrodes production factory. Specimens took from near areas of breakage field and analyzed. As a result, 4 different breakage types defined. These are point inclusion originated breakage, sectional inclusion originated breakage, delamination breakage and tensile breaks. Point inclusion originated breakage and sectional inclusion originated breakage are the most hazardous ones. In this breakage types; inclusions sizes are xxiii close to 20 μm or bigger than 20 μm. It has been found that, sectional inclusion originated breakage has not seen in the wire rods using by submerged entry nozzle method. Supplier D ensures this production method. In delamination and tensile breaks, the reasons are drawing die, lubricant solution or a problem in drawing machine. So, if breakage types have been defined accurate, these breakage types will not be seen in a while. Models of lubricant on wire defined by 4 types. Advantages and disadvantages of these 4 types investigated. The work and friction coefficient for models of lubricants are shown. Calcium stearate and sodium stearate found as appropriate lubricants for wire drawings. Calcium stearate usage recommended for the first 2 die. The mix of two lubricants can be used for other dies.