FAQ 1: Galvanic/Dissimilar Metal Corrosion
What is it and how to avoid it
Contact between dissimilar metals occurs frequently but is often not a problem. The aluminium head on a cast iron block, the solder on a copper pipe, galvanising on a steel purlin and the steel fastener in an aluminium sheet are common examples.
FAQ 2: Cleaning Your Indoor Stainless Steel
Quick and easy tips for keeping that shine
Retaining a sparkling finish on stainless steel surfaces is just a matter of a few simple steps. And you don't need expensive products or special equipment - ordinary household cleaners are usually all that's required. You just need to bear in mind a few easy DOs and DON'Ts...
FAQ 3: Magnetic Effects of Stainless Steels
The magnetic properties of materials are affected by their composition, metallic structure, processing methods and physical condition. Ferromagnetic materials are strongly attached to a permanent magnet and may also be magnetised to act as a permanent magnet.
FAQ 4: Testing for Grade Confirmation
Raw material price fluctuations and increasing demand for stainless steel have driven demand for lower cost alloys as alternative to the traditional "300" series steels. This has been met through a range of existing and new, innovative steels with difference properties, performance and availability. But as with the traditional stainless steels, you can't tell what they are by looking at them. This article describes a range of test methods available for grade confirmation.
FAQ 5: Galling and its Control
Austenitic stainless steels are widely used for corrosion resistant bolting. One of the major problems in use is that disassembly is difficult because nuts and bolt seize. This phenomenon is known as galling and it is the most prevalent with intermittently operated, slowly sliding surfaces. It is caused by cold welding of the high points of clean, oxide free metal left when the oxide film is dislodged by surfaces rubbing against each other.
FAQ 6: Preventing Coastal Corrosion (Tea Staining)
When used properly, stainless steel enjoys a strong and enduring reputation for visual appeal and structural integrity in a wide range of applications and environments. But, like all materials, stainless steel may become discoloured over time, impairing the overall look. This brown discolouration - tea staining - has been identified in coastal applications in Australia and overseas.
FAQ 7: Guidelines for Use of Stainless Steel Underground
Stainless steel can provide excellent service underground. It is stronger that polymers and copper, and its resistance to chlorides and acidic soils is significantly better than carbon or galvanised steels.
FAQ 8: General Corrosion Resistance
The normal state for stainless
Stainless steels resist corrosion because they have self-repairing "passive" oxide film on the surface. As long as there is sufficient oxygen to maintain this film and provided that the level of corrosives is below the steel's capacity of the particular material to repair itself, no corrosion occurs. If there is too high a level of (say) chlorides, pitting occurs. As an example, 316 works well in tap water (<250ppm) all over Australia, but will rapidly corrode in seawater because seawater has very high chloride levels (20,000ppm).
FAQ 9: Welding Dissimilar Metals
Welding the common austenitic stainless steels such as 304 and 316 to each other or themselves is routine and the easiest of fusion welding. Nevertheless, there are many situations where it is necessary to weld stainless steel to carbon steel. Two common examples are balustrade posts connecting supports to stainless steel vessels. There are differences in physical properties such as thermal conductivity and expansionl, magnetic properties, metallurgical structure and corrosion resistance, which all require attention. This article outlines the necessary procedures for satisfactory welding, including reference to standards, and explains necessary precautions.
FAQ 10: Thermal Expansion and Design of Stainless Steel Fabrications
Either while being welded or glistening in the summer sun, the three major families of stainless steel behave differently to each other, carbon steels, aluminium and copper alloys because, as shown in the bar chart (opposite page), the coefficient of thermal expansion and conductivity - and their ratio - varies.