[ Welding / Additive Manufacturing ] is more difficult to weld , and is more prone to cracking . Medium carbon steel is welded with stainless steel using a low-hydrogen welding process or controlled hydrogen fillers . High carbon plain steel - High carbon steel containing 0.60-1.0 % carbon and 0.30-0.90 % manganese is extremely hard and strong . It has poor weldability and is difficult to weld without cracking . As the carbon content of steel increases , the steel becomes stronger and harder as well as less ductile . High carbon steel is typically considered “ hard to weld ” due to the hardening effect of heat at the welded joint . It may readily form the hard and brittle martensite phase as it cools from welding . Because of the high carbon content and the heat treatment usually given to this steel , its basic properties are impaired by arc welding . Therefore , this steel requires thorough preheating and post-heating to avoid this . Austenitic stainless steel , such as grade 304 stainless or grade 316 , can be welded to plain carbon steel using MIG and TIG welding . During MIG welding , filler material is preferred [ 4 ] . Galvanised steel - Stainless steel has good weldability to galvanised steel . The zinc coating around the area to be joined is removed before welding as molten zinc , if present in the weld fusion zone , can result in embrittlement or reduced corrosion resistance of the finished weld . [ 5 ]
[ Welding / Additive Manufacturing ] is more difficult to weld , and is more prone to cracking . Medium carbon steel is welded with stainless steel using a low-hydrogen welding process or controlled hydrogen fillers . High carbon plain steel - High carbon steel containing 0.60-1.0 % carbon and 0.30-0.90 % manganese is extremely hard and strong . It has poor weldability and is difficult to weld without cracking . As the carbon content of steel increases , the steel becomes stronger and harder as well as less ductile . High carbon steel is typically considered “ hard to weld ” due to the hardening effect of heat at the welded joint . It may readily form the hard and brittle martensite phase as it cools from welding . Because of the high carbon content and the heat treatment usually given to this steel , its basic properties are impaired by arc welding . Therefore , this steel requires thorough preheating and post-heating to avoid this . Austenitic stainless steel , such as grade 304 stainless or grade 316 , can be welded to plain carbon steel using MIG and TIG welding . During MIG welding , filler material is preferred [ 4 ] . Galvanised steel - Stainless steel has good weldability to galvanised steel . The zinc coating around the area to be joined is removed before welding as molten zinc , if present in the weld fusion zone , can result in embrittlement or reduced corrosion resistance of the finished weld . [ 5 ]
Aluminium - It is possible to weld aluminium with stainless steel . Aluminium-steel-aluminium joints find applications in aerospace , automotive and shipbuilding to reduce the weight of the structure , thereby enhancing efficiency . There is a huge difference in melting point between aluminium alloy and steel , which makes this a great disadvantage for the process . Stainless steel and aluminium are joined via arc welding ; two special techniques have been developed to isolate the metals from each other during the arc welding process . Very brittle intermediate compounds are not formed during welding .
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The first method uses bimetallic transitions , in which aluminum and stainless steel are joined by methods that do not create the compound and allows the joining of the two metals by only welding aluminium to aluminium and stainless steel to stainless steel .
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In the second method , the stainless steel is coated with aluminium .
This is sometimes achieved by dip coating ( hot dip aluminising ) or brazing the aluminium to the surface of the steel . Once coated , the steel member can be arc welded to the aluminium member , if care is taken to prevent the arc from impinging on the steel [ 6 ]
Copper - Copper and stainless steel can be welded together , but it is extremely difficult and offers very little structural strength . [ 7 ] The melting point of stainless steel is much higher than that of copper . Electron beam welding ( EBW ) is the preferred welding process , mainly because EBW is a great process for welding copper in general .
Tungsten - Tungsten is an ideal welding material for stainless steel due to its high melting point and strength and is used to easily weld stainless joints . Thoriated tungsten electrodes , containing 1-2 % thorium oxide ( ThO 2 ), are ideal for high amperage welding of stainless steel . Tungsten is welded in a very pure atmosphere of either inert gas ( gas tungsten-arc process ) or vacuum ( electron beam process ) to avoid contamination of the weld by interstitials [ 8 ]
References available on request
Airbus Helicopters boosts competitveness with AM
Airbus Helicopters has opened a new 3D printing centre at its Donauwörth , Germany , site , significantly expanding its in-house capacity for this innovative process .
Text & images by Airbus Helicopters
Airbus Helicopters now operates three additive manufacturing ( AM ) machines for components made of titanium , four for plastic parts and , as a new element , one that can produce components made of aluminium . AM offers several benefits compared to conventional manufacturing . It can be used for serial production as well as for components for prototypes such as the electrically powered CityAirbus NextGen and the experimental high-speed helicopter , Racer . “ Our extensive capabilities in this process along the manufacturing chain are a real competitive advantage ,” said Stefan Thomé , Managing Director of Airbus Helicopters in Germany . “ Among other advantages , 3D printing can reduce the weight of aircraft components which leads to less fuel consumption . Such potential can bring financial benefits and contribute to reducing CO2 emissions during operations .”
Resource efficiency Other advantages of 3D printing include a significant increase in resource efficiency in the manufacturing process and high flexibility . Components with new configurations can be printed as individual pieces or in small series for testing purposes . This also makes the process appealing for building prototypes . Additive layer printing uses laser beams to melt metal or plastic powders , so the desired shapes are
© Airbus Helicopters 2022 - Christian Keller
created layer by layer , making it easier to produce complex structures than with conventional methods . A conventional manufacturing process requires up to ten times more raw material than the final product , whereas additive manufacturing requires only 1.5 times as much . Since 2017 , Airbus Helicopters has mass-produced more than 9,400 locking shafts for the doors of the Airbus A350 , using the additive process as part of the Donauwörth-based airplane door business . Eleven tonnes of titanium powder have been used in Donauwörth for printing the locking shafts .
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