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Stick Welding Cast Iron with 6013 ElectrodesIron welding procedures -
Here is their advice:. The three primary grades of cast iron include gray iron, ductile iron, and malleable iron. Gray iron is the most common form of cast iron, presenting a challenge for welders when the graphite flakes enter the weld pool and cause weld metal embrittlement.
Ductile and malleable iron are less brittle because of their microstructural differences. Both have spheroidal carbon microstructures from their manufacturing processes.
Castings need to be properly prepared before welding. Remove any paint, grease, oil, and other foreign materials from the weld area. Then apply heat carefully and slowly to the weld zone for a short time to remove trapped gas in the base metal.
An oft-used technique to test the cleanliness of the surface is to deposit a weld pass on it. If impurities remain on the iron, the weld will be porous.
You can repeat the process until porosity is no longer present. The main reason for controlling the heat is thermal expansion. When metal is heated, it expands. If the entire object warms and expands at the same rate, there is little stress. However, it creates stress and cracking when the heat is localized in a relatively small heat-affected zone HZ.
Preheating minimizes the thermal gradient between the casting body and the HZ, lowering the tensile stress caused by welding. Choose the welding technique that is most suitable for the iron alloy.
The three most common processes are stick, oxy-acetylene, and braze welding, with stick being the most popular. With stick welding, three primary filler electrodes work for cast iron: copper alloy, cast iron covered, and nickel alloy. The nickel alloy electrodes are quite popular for cast iron because the nickel-iron weld is stronger and has a lower coefficient of thermal expansion, reducing stresses and increasing resistance to cracking.
Direct the electric arc at the weld pool instead of at the base metal. Doing this minimizes dilution. Use the lowest current setting approved by the manufacturer to help reduce heat stress. Preheat the pieces to at least °F before welding with copper or cast iron or electrodes.
No preheating is needed with nickel electrodes. Learning how to weld cast steel is less of a challenge compared to cast iron.
However, even though cast steel has similar properties to rolled steel, some differences make it harder to weld. Although you can weld cast steel using the MIG or TIG processes, many welding experts recommend stick welding with E rods for low-carbon alloys and stainless-steel rods for hard-to-weld castings.
One of the issues with welding cast steel is avoiding distortion. Here are some suggestions to help with that:. Thick castings often become hard after welding, and cold cracking may occur long after completion.
Or, any added impurities can concentrate in the center of the weld, causing a crack before the weld even cools. Remember, the longer a weld takes to cool, the stronger the joint will probably be.
Iron is brittle, and heat causes stress on the material and weakens structural integrity. The American Welding Society AWS has several standards devoted to the welding of iron castings.
The standard was originally written and approved by ANSI in July and documents the metallurgy and weldability of the various cast iron alloys, filler metals and welding processes. The cast microstructure must be considered when choosing an appropriate welding process.
An example of a weld repair that has been performed for many years is in automotive stamping dies. The stamping dies used to fabricate the entire body side panels, hood, trunk, fenders, and doors are typically made of gray, or most often ductile cast iron. Low volume, specialty shaped hoods might be made from gray iron.
However, all high-volume stamping dies are made of ductile iron. These stamping dies are often welded to change the shape of the component without having to purchase new dies.
A new set of stamping dies could potentially cost hundreds of thousands of dollars and take eight to 12 weeks or more to produce. The welding practices and procedures have been thoroughly studied and documented and welders are certified to perform the welding task.
Therefore, it is much more economical to make small modifications this way. Stamping plants have used weld repairs when a part or tool gets accidentally left behind in the dies i.
The out-of-specification wrench-shaped die is detrimental to the quality of the stamped fender. Dies are then removed, welded in the depressed area from the wrench and then machined back to specification. A similar welding method is utilized in cosmetic repairs to cast surfaces.
An example of structural welding of cast iron is in the miles of welded ductile iron pipe under ground transporting liquids with water-tight welds all across the country. There are well defined procedures for welding pipe and a qualification process for the welder.
The welding standards include the importance of generating WPS Weld Procedure Specifications , PQR Process Qualification Records and WQT Welder Qualification Tests. The purpose of the PQR is to document settings, materials, and methods to develop the WPS for a known material and application.
A welder qualification test utilizes the Weld Procedure Specification for a welder to perform a weld to the specification.
The welded product is then evaluated mechanically and microstructurally. If the welder passes the test to the WPS, they would then be certified to weld product that requires that specific WPS. The welder would have to recertify on an established time basis.
This is covered in another AWS Standard, AWS B2. These welding standards are available on the AWS website at: www. Welds have several classifications. A Class 1 weld is a structural weld. The weld will see high stress. The failure of the weld will result in potential damage to equipment or personnel.
A Class 2 weld is a weld that will not be under high stress. A failure of a Class 2 weld will result in no hazard or harm but affect equipment operation. A Class 3 weld is more of a cosmetic weld. This weld, if it fails, will not create hazard or harm, and it will not affect equipment operation.
A few other cast iron alloys may be encountered, especially in the agricultural industry. White iron is often utilized for components that will experience abrasive conditions i.
Other white iron applications are in the mining industry, digging through miles of earth. Attempting to weld white iron typically results in cracking. Lower quantities of malleable iron and compacted graphite irons are cast for various applications. Due to the similar matrix structures and free graphite in these irons, they should weld similar to gray and ductile iron parts.
As with most welding applications, there are several methods that can be utilized or selected based on the application. Probably the most used are welding rods. The welding standard, AWS A5. The main concentration of this paper with regards to welding methods will be in the chemical and mechanical properties of the weld metal available.
The American Welding Society standard provides a guide for weld metal manufacturing with regard to chemistry. The standard for welding cast irons is: AWS A5. The American Welding Society also has standard AWS D This standard is a great reference guide to welding iron castings.
Table 1 shows the chemical composition requirements for undiluted weld metal for shielded metal arc and flux cored arc welding. An internet search of welding rod suppliers can produce a solid list of weld rod or wire options. Various suppliers may only share limited information, which may require an inquiry to obtain necessary material properties i.
Table 2 lists welding materials by name and some of their properties. Talking with a technical representative from a weld material supplier is also helpful. An example from Table 2 would be the use of Supercast for gray iron weld applications and Ultracast for ductile iron applications.
In speaking with the sales representatives for these two products, this was the recommendation. The recommendation would be to weld a test piece with both materials and evaluate the results.
In tests performed for an organization involved with automotive stamping dies, it was found that one weld material worked very well for ferritic ductile iron but did not perform well on pearlitic ductile iron.
The American Welding Standard AWS lists several approved weld methods. The most common are: Gas Metal Arc Welding GMAW, also called MIG welding. Shielded Metal Arc Welding SMAW, also called stick welding.
Often, Gas Tungsten Arc Welding, GTAW, also known as TIG welding , is assumed to be the method for welding aluminum or stainless steel. This is a very good method for welding whenever feasible. However, most industrial plants have only stick or Metal Inert Gas MIG welding capability.
The good news is that this technology can provide robust weld joints. All these welding methods are covered in the AWS standard for welding cast irons. The most common methods for good structural welds are SMAW, GMAW, and GTAW.
In the case of machined surfaces, TIG welding might be the best option to prevent weld spatter from sticking to the machined surface. Several considerations for welding gray and ductile cast iron should be made.
The first is determining the type and grade of iron to be welded. At a minimum, knowing the chemistry and mechanical properties of the iron will be helpful in choosing the weld filler material. In some cases, iron is welded to other materials, typically steel.
Some casting processes incorporate steel components in the mold to join the two materials. This is likely the easiest form of joining steel to iron.
Examples include brake rotors and heavy truck drums that utilize steel mount flanges with gray iron braking surface materials. However, the steel is essentially annealed by the casting process. If the properties of the steel are not to be annealed, welding the two materials is the correct option.
The next step is to find a weld material with similar mechanical properties. If there are several material options with the desired mechanical properties, weld test pieces with each of the weld materials, perform weld bend tests, and evaluate the weld under a microscope.
Figure 1 is an example of a good weld interface between the ductile cast iron and the weld material. Other than the change from the weld material to the iron, there should be no defects.
A bad weld may have gas porosity or even a well-defined border between the weld material and the cast iron.
Proceudres you are an experienced Iron welding procedures, you probably Iorn know that welding cast iron lrocedures cast procedyres can be challenging. Cast iron has a high Iron welding procedures content Astaxanthin and eye strain around 2 to 4 Iron welding procedures, procedires ten times more than most steel. It might also contain higher levels of sulfur and phosphorus, making it harder to weld without cracking. On the other hand, the chemistry of cast steel is often similar to low-carbon cold rolled steel, so in many cases, it will be easier to weld than cast iron. Still, higher amounts of silicon and manganese in cast steel can make welding it much more difficult.
When you procddures about welding, you likely Natural energy enhancer drinks primarily about steel. Proceures iron is also common, but it Iron welding procedures its own unique challenges. Chemically, not all that much. Both types of metal are iron and carbon alloys. While this small percentage might not seem like it makes a huge difference, it actually does. The higher carbon content of cast iron, however, reduces that ductility. It just breaks.
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