Selecting Hardfacing Wear Plate
What are the differences between Hardfacing, Chromium Carbide Overlay (CCO), Hardfaced Wear Plate?
Even though they have similar names, chromium carbide hardfaced wear plates come in varying levels of quality depending on the method of production and the quality of raw materials!
Hardfaced wear plate products can be called different names including Chromium Carbide Wear Plate, Chromium Carbide Overlay (CCO) plate, Chrome Carbide Hardfaced, and Hardfaced Wear Plate.
Hardness is not the best metric for determining the quality or wear life of hardfaced wear plates!
The most important factors to consider when selecting hardfaced wear plates are:
(1) the production method
(2) the distribution of metal carbide (MC)
(3) the chemical composition and quality of the raw material
(1) Production Method
Hardfaced wear plates that are manufactured by bulk welding process exhibit a much more superior quality in comparison to those that are manufactured by flux cored wire. Bulk welding process enables the manufacturer to control the underlying
chemical composition of the wear plates by varying degrees as well as allow for the optimal dilution between the hardfaced weld layer and the base metal layer.
Figure 1 shows an example of a hardfaced wear plate manufactured by flux cored wire exhibit uneven and rough surface as well as large gaps between the weld beads. The roughness of the surface will ultimately affect the life time of the wear plate.
Figure 2 shows a prime example of a premium quality hardfaced wear plate manufactured by bulk welding process; the surface is relatively smooth, with even welding along the length/width of the plate.
Figure 1. Bulk Welding Procress
Figure 2. Typical wear plate manufactured with flux cored wire
Figure 3. MC-3 wear plate manufactured by bulk welding process
(2) Chromium Carbide Distribution (microstructure analysis)
Unlike the conventional quenched and tempered wear resistant plates, the abrasion resistant value of hardfaced wear plates cannot be measured from hardness testing alone. For example, a typical martensitic steel plate can have the equivalent hardness compare to hardfaced wear plates, but the abrasion resistant qualities are incomparable.
The abrasion resistant level for hardfaced wear plates can be determined by the percentage of chromium (%) in the overall chemical composition. The relationship between chromium and carbon percentage to the weight loss from abrasion testing (ASTM G65) can be seen in Table 1. (http://www.superiorconsumables.com/chrome-carbide-overlay-plate/)
Figure 4. Prime example of good chromium carbide dispersion microstructure of MC-3 Du-All grade (https://mc3wearplate.com/product-grades/duall/)
Table 1. As the percentage of Chromium increases the amount of weight loss decreases indicating a better abrasion resistant.
(3) Chemical Composition and Raw Material Quality
Selecting the optimal chemical composition for hardfacing layer is crucial in obtaining good mechanical properties, which includes not only abrasion resistance, but also formability and impact resistance. Furthermore, the quality of the raw chemical compounds is crucial in obtaining the best quality product e.g. ferrochrome, an important chemical compound in hardfacing plate manufacturing, that comes from China may contain large amount of impurities as compare to reliable sources from mines in South America or Europe.
For more information >> www.mc3wearplate.com