Classification of the Hardfacing Alloy
All multiprocess welders know well that there is no one standard method for the classification of the hardfacing alloy and for the specification of the different weld rods, welding wire and electrodes. In fact, as TIG welders, Stick welders, MIG welders and Arc welders know well, most of the hard facing electrodes which are available cannot be set under the most used specifications.
Most of the suppliers of filler metal are offering data setting classes and categorize their products into these classes. Some of the suppliers also offer information on how specific products can be applied and used in the different industries. In this way the multiprocess welders will know when and how to use them.
Like many of the Stick welders, TIG welders, Arc welders and MIG welders know, the American Society for Metals Committee on Hardfacing has established the best possible classification of the hardfacing alloys. According to that classification, the multiprocess welders can spot five main groups which are classified according to their alloy content and they have several subdivisions which are based on the main alloying elements.
Most of the alloys are found as solid filler rods, in coins or as covered electrodes. There are also hardfacing alloy materials in the form of powder, used in special applications. Below is present a short description of the five main groups which contain allows and when their usage is recommended.
Group 1 - multiprocess welders say that these are low-alloy steels, the main alloying element in which being chromium. This group has two subgroups – one that has alloy content between 2 and 6 %, including carbon. These alloys are used as buildup materials and the other group with higher content of alloy between 6 – 12 %. Several of the alloys in the group have higher carbon content, which exceeds 2 % and include several alloy cast irons.
As Arc welders, Stick welders, TIG welders, and MIG welders are aware, the Group 1 alloys have the greatest impact resistance of all hardfacing alloys except for the austenitic manganese steels and have better wear resistance when compared to the medium and low carbon steels.
These hardfacing alloys are among the least expensive ones and are thus very popular. These alloys further have high compressive strength and also fair resistance to erosion and abrasion.