Cemented carbide has a series of excellent properties such as high hardness, wear resistance, good strength and toughness, heat resistance, corrosion resistance, etc. Especially its high hardness and wear resistance, even at a temperature of 500℃also remains basically unchanged, at 1000℃still has a very high hardness. Known as "industrial teeth", it is used to manufacture cutting tools, cutting tools, cobalt tools and wear-resistant parts, and along with the development of downstream industries, the market demand for cemented carbide is increasing. The future of high-tech weapons and equipment manufacturing, the progress of cutting-edge science and technology, and the rapid development of nuclear energy will vigorously increase the demand for high technology and high-quality stability of cemented carbide products.
Cemented carbide is poorly weldable and often prone to weld cracks if not handled properly. The reason for this is that it has a high carbon content, and the uncleaned surface layer after sintering often contains more free state carbon (carburization), which can hinder the wetting of the solder. This leads to the appearance of cracks. However, cemented carbide welding is a process that is often required, and Jetvision has the expertise to minimize and avoid the appearance of cracks. The following are the points to note when welding carbide to reduce the appearance of welding cracks.
First, the heating method is controlled to reduce the crack generation. Welding temperature control is about 30 ~ 50℃greater than the melting point of the solder selected when the melting point of the solder should be lower than the melting point of the tool bar 60℃, welding flame should be uniformly heated from the bottom up slowly pre-warmed for welding, so the requirements of the blade groove and blade welding surface to form a consistent, local over-warmed will make the blade itself or the blade and tool bar temperature difference is large, the thermal stress will make the blade edge chipping so require pre-warming first on the tool bar pre-warming, if Blade and tool bar together with heating should be back and forth to move the flame back and forth into the line heating, so that you can avoid the concentration of warming caused by local overheating and cracking.
Second, familiar with the impact of the shape of the knife slot on the formation of cracks. The shape of the knife slot is not consistent with the welding surface of the blade or a large difference, the formation of closed or semi-closed slot shape, so it is easy to cause too much welding surface and welding layer is too large, due to thermal expansion after the shrinkage rate is not consistent, but also easy to cause excessive stress in the blade welding, the formation of chipping. In the satisfactory use of the required weld strength requirements, should be as far as possible to reduce the area of the brazing surface .
Third, clever cooling. Welding or after welding, such as rapid cooling and poor dehydration of the flux, are easy to make the blade burst and crack through, so require good dehydration of the solder, after welding absolutely can not be placed in the water rapid cooling, to be placed in lime, asbestos powder, sand, etc. in the slow cooling, at about 300℃insulation for more than 6 hours with the furnace cooling.
Fourth, pay attention to the impact of defects in the bottom surface of the knife slot on the crack. Blade and knife slot contact surface is not flat, such as black skin pockmark, local inequality reasons, so that the welding can not form a flat combination, which will cause uneven distribution of welding material, not only affect the strength of the weld and cause stress concentration, and easily lead to blade fracture, so the blade to grind the contact surface, the welding surface of the blade knife slot should be cleaned, in the milling cutter blade slot with the blade in the process, the blade is required to extend the tool bar Support part is not more than 0.5mm, if the blade out of the tool bar support part is too large or tool bar support part is weak, it will make the tool in the welding process to withstand the tension and fracture phenomenon.
Fifth, pay attention to the impact of the blade secondary heating on the formation of cracks. Blade in the brazing, purple copper brazing material does not completely fill the gap, sometimes there will be individual false welding, and some tools in the process of furnace, the blade in the tool bar fell, so the need for secondary heating, so that the binder cobalt serious burn loss, WC grain growth, may directly lead to blade cracking.
Cemented carbide is hard and brittle, if there is a slight negligence in the welding process, it will be scrapped because of the cracks, so we need to understand the points to note when welding cemented carbide to avoid welding cracks.
Hunan Jetvision Industrial Co.Ltd offer kinds of tungsten carbide products for mining, such as carbide button, carbide insert for mining, carbide coal button, carbide PDC substrate, etc. With top quality and low factory price.
Hunan Jetvision is one of the leading Tungsten carbide manufacturers and suppliers with over 20years experience of carbide button production and technology, we mainly manufacture, stock and supply dome button, Parabolic inserts, Spherical inserts, Conical inserts, Wedged inserts, Spoon inserts, Flat top inserts, Road milling picks inserts, etc. at the best factory prices.
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