Abrasion is the process in which a material begins to scratch, scuff or rub away. This is usually an undesirable effect caused by regular use or exposure to the elements; although it can also be intentionally imposed in a controlled environment using an abrasive substance. A materials resistance to abrasion can be measured by a range of different test methods; these tests usually use a specified abrasive or an alternative method of abrasion.
These standardised measurements offer two quantities:
- Abrasion rate – the amount of mass lost per 1000 cycle;
- Normalised abrasion rate – the ratio of abrasion rate with that of a specific reference material.
Abrasive resistant steel is a material that is completely unaffected by abrasion, so the steel will not scratch or rub away over a long period of time.
- Mining – used to manufacture armoured face conveyors in order to increase their service life.
- Quarrying – abrasive resistant steel is used to make anything from small constructional pieces to profiled parts and hefty area plates.
- Construction and earthmoving – abrasive resistant steel provides resistance against wear and tear in dump truck bodies and buckets. This increases the service life of the equipment significantly.
- Conveying – by delivering stronger, tougher and more resistant steel plate solutions we can extend the lifetime of conveying equipment.
Welding Properties of Abrasive Steel
ABRAZO 400 is a type of abrasion resistant steel plate which can be readily welded under standard conditions using MIG, MMA and SAW without the need for preheating. A combined thickness of 60mm can be welded if hydrogen controlled electrodes are employed. Consumables must be dried under accordance of scale D of BS 5135.
The welding of ABRAZO 400 can be carried out successfully using heat inputs in the scale of 1.5-3.0kJ/mm and the interpass temperature cannot exceed 250°C. The consumables for both of these materials are chosen on the foundation of whether or not the weld material is exposed to an abrasive medium. If joints are not exposed to wear climates then low-strength hydrogen controlled mild steel electrodes are used. When the weld material is exposed to abrasive agents then you should use hydrogen controlled electrodes for capping passes that produce a weld metal deposit with a similar hardness to the parent plate.
Machinability of Abrasive Steels
Drilling – armour piercing HSS-Co drills (point angle of 125°-130°) are usually used in the drilling process. It is vital that you establish a rigid holding set up as well as an appropriate cutting speed, tool geometry, feed rate and cutting fluid. Make sure to place supporting bars or a mild steel backing plate beneath the plate you are drilling.
Punching – abrasive resistant steel can be cold punched, but this operation is a bit more difficult than punching mild steel as the punch wear will increase. This action is not recommended for ABRAZO 450 or 500 grades.
Milling – this process can be influenced by the inflexibility of the machine tool and the workpiece clamping. In addition to this, little variations in feed rates and cutting speeds can significantly affect the tool life cycle.