Welding-cast-iron deals with classes known as Gray, Malleable and Nodular or Ductile according to typical appearance of their microstructure, which affects their properties. Properties of Cast Iron The properties sought for when selecting cast iron are usually economy, good castability even in complex forms, damping of vibrations, resistance to heat checking or heat shock, although strength may not be the primary consideration.
In the 18th century, as cast iron became more widely available, it was quickly adopted for structural and decorative purposes.
The beauty of the material was that it could be produced in an enormous variety of shapes and designs and mass-produced, allowing load-bearing columns and elaborate facades to be created at a fraction of the cost of traditional stone carved ones.
This development coincided with a period of rapid growth in trade and commerce, reflected in magnificent buildings such as the Doncaster Corn Exchange, Dewsbury Market Hall and the grand designs of railway stations throughout the country.
Now over a century old, these buildings are often of considerable beauty, as well as being of great architectural and historic importance, and many are listed, necessitating a meticulous approach to repair and restoration if structural failure occurs. Grey cast iron, the form most frequently encountered in Victorian buildings, was generally produced in green sand moulds.
This process allowed for the reproduction of fine detail, but also presented an inherent problem of brittleness in the material. Today, subsidence is one of the most common reasons for structural failure in cast iron structures. Due to the method of construction it may not be noticed until the failure has reached quite an advanced stage.
The reason for this is that in structures consisting of cast iron columns and beams, it was usually necessary to disguise the bolted joints with some kind of decorative covering.
These covers can hide underlying problems and, in this sense, the magnificence of decorative cast ironwork can also be its downfall. Another common cause of structural failure is water ingress between sections of cast iron, particularly if previous remedial work has been carried out using stainless steel bolts which have not been isolated using nylon washers.
In the presence of moisture, this rapidly leads to bimetallic corrosion and subsequent corrosion and cracking in the area surrounding the bolts. In one case, during the redecoration of an Edwardian market hall, a large section of decorative casting fell out as paint was being scraped off it.
To determine the extent of the problem, engineers working from cherrypickers removed small squares of material from some of the decorative castings to reveal the bolted connections between the columns and the steelwork. They found that virtually all the bolts they inspected had failed: Although cast iron was originally introduced as a fire-proof material in textile mills and warehouses, under intense heat it does not perform well as a building material.
Where fires have ravaged Victorian cast iron buildings, the Doncaster Corn Exchange being one example, there has often been serious structural failure. Problems are compounded when the blaze is extinguished using fire hoses as the sudden change in temperature causes further embrittlement and cracking occurs in columns and beams.
This is often accompanied by the complete disintegration of decorative cast iron features. Again due to the brittle nature of grey cast iron, impact damage can have devastating consequences.
Examples of this are provided by a series of elaborately decorated cast iron fountains situated on roundabouts in the Avenues area of Kingston upon Hull. Over a period of time all were shattered as the result of road traffic accidents and had to be repaired.
Cast iron can be repaired using a variety of processes according to the exact nature of the cast iron and the circumstances in which the repair must be performed.ASME STANDARD SPECIFICATION SA Standard Specification for Carbon Steel Tee Rails SA Standard Specification for Carbon Steel Girder Rails of Plain, Grooved, and Guard Types.
Cast irons can be conveniently grouped according to their structure which influences their mechanical properties and weldability; the main groups of general engineering cast irons are shown in Fig.
1. The weldability, also known as joinability, of a material refers to its ability to be welded. Many metals and thermoplastics can be welded, but some are easier to weld than others (see Rheological weldability).
Heroes and Villains - A little light reading. Here you will find a brief history of technology.
Initially inspired by the development of batteries, it covers technology in general and includes some interesting little known, or long forgotten, facts as well as a few myths about the development of technology, the science behind it, the context in which it occurred and the deeds of the many.
Shock Absorption and Weldability Ductile iron has superior shock absorption to steel. The average damping capacity for ductile iron is times greater than SAE steel (reference - P. ASM Cast Iron . Welding-cast-iron is the subject of this page..
What is in here for me? What benefits can be found here? Essentially a short overview of problems concerning Welding-cast-iron.. However as types and conditions of various cast irons can be very different, so could be the problems and the answers..
For any questions on these subjects, write us by e-mail.