Welding steel with copper and its alloys.
In the equilibrium state at room temperature copper dissolves in the alfa - Fe in an amount up to 0,3%, a copper iron in an amount up to 0.2%. Fragile - intermetallics are not formed. Due to the high cooling rates during welding in the transition layer is formed supersaturated solid solution of copper and iron, but the content up to 2-2,5% Fe structurally free iron is not detected. The boundary of fusion between the steel and copper - is sharp, with inclusions of phase enriched in iron of various sizes. On the part of steel adjacent to the seam, the grain size increases within a zone of width 1.5-2.5 mm. Microhardness fusion zone reaches 580-620 kgf/mm2.
Worsens mutual solubility of iron and copper in the presence of carbon steel, and improves the manganese and silicon. Manganese reduces the critical point A3 and extends the a-solid solution in which copper is dissolved in much larger quantities, and silicon deoxidized molten pool and strengthens the grain of the solid solution. difficulties in welding and cladding copper to steel related to its physico-chemical properties, high affinity of copper to oxygen, a low melting point of copper, a significant absorption of liquid copper, gas, different values of thermal conductivity, linear expansion, etc. (One of the major potential defects during welding should be considered in the formation of steel under a layer of copper cracks filled with copper or its alloys. This phenomenon explains wedging action of molten copper that penetrates the mikronadryvy in the steel along the grain boundaries under the simultaneous action of thermal stresses of tension. in carbon and low alloy steels (FCZ 10HSND, etc.), small cracks and their sizes are small, and in steels with an austenitic structure, in particular, 18-8, the number and size of fractures increase dramatically. For steels 18-8 effective barrier to crack mentioned is the introduction of the ferrite phase. When the content of more than 30% ferrite in steel 18-8 penetration of copper in Steel is not observed, and this is because the ferrite is not wetted by the penetration of copper and copper mikronadryvy happens. To reduce the risk of formation of these cracks is recommended to weld on the minimum heat input as a filler metal to use Nickel MNZH 1.5 or bronze BrAMts 9 - two. presence of nickel and aluminum reduces the activity of the impact of liquid metal in mikronadryvah on steel, which reduces the danger of deep cracks in the steel. Copper, brass and bronze have successfully welded with steel fusion welding of all ways to the same modes as the steel parts of the sections but the arc of several joint shift in the direction of copper or its alloys. for the welding of copper, bronze BrAMts 9-2, BrKMts 3-1 L90 brass with steel type StZsp; St4sp, 10, 09G2 apply: a) for manual welding - Electrodes with cover of "Komsomolets", and b) for submerged arc welding - fluxes OSC-45, AN-26, etc., and wire marks Ml, M2 and BrKMts 3-1 and others, c) for welding in inert gas-shielded - wire marks BrKMts 3-1 BrAMts 9-2, MNZH 5-1. In some cases, requires pre-heating of the product. MNZH 5.1 alloy welded to carbon and low alloy steels with a rod electrode alloy coated MNZH 5.1 ST, and submerged arc welding with OSC-45, or shielding gases - electrode wire marks MNZH 5 -1. When welding provided the welded joint strength balance (for metals) under the action of static loads. Welded joints have satisfactory ductility. Thus, for the copper compounds MSp or alloy steel with 5.1 MNZH St4sp in manual welding bending angle is 40 - 85 deg., Argon and at 110-180 deg. Higher quality welds with TIG welding alloys MNZH 5.1 due to the fact that in this case, the weld metal iron content does not exceed 8-10%, while in manual welding reaches 50-55%. Optimum deposition of copper on steel demand to avoid melting the steel, so that it wets (for this the temperature greater than 1100 deg. C) and duration of contact of copper with steel at this temperature would not be less than 0.01-0.015 s. to connect copper and its alloys to steel recommended for TIG welding of tungsten electrode, and for surfacing steel, nonferrous metals - cladding current-carrying plasma jet with a filler wire. Welded joints have a high fatigue strength. Welding of steel and titanium. One of the main problems in welding titanium with steel is the choice of welding materials, methods, and welding conditions under which prevented or would be dramatically suppressed the formation of brittle intermetallic phases FeTi and Fe2Ti. Direct welding of titanium and steel does not give positive results. Practical application is welding in argon tungsten arc welding, and through the intervening insert. Good results were obtained using a combined insert, consisting of technical tantalum (sigmaV kgf/mm2 = 70) and heat treatment BrB2 bronze. bronze welded to carbon steel or austenitic steel, TIG welding, non-consumable electrode and the tantalum and titanium - in chambers with controlled atmosphere. Tensile bond strength of 49 kgf/mm2 bronze, bronze with 60.5 kgf/mm2 quenching (hardening prior to welding). Combined BrB2 insertion of bronze and niobium using TIG tungsten electrode in a chamber with controlled atmosphere OT4-1 titanium thickness of 0, 8 and 2 mm. The strength of the connection at a thickness of 0.8 mm sigmav = 53 - 66 kgf/mm2, bending angle 72-180 degrees., At a thickness of 2 mm sigmav = 40 - 45 kgf/mm2, bending angle 41-61 degrees.
See also:
Welding of Copper
Welding of Steel and Aluminum
Welding Steel with Copper
Dissimilar Metals, Nonferrous
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