Surfacing is a kind of welding process that has a metal alloy layer (with wear-resistant, corrosion resistance, heat resistance future) welded on work-piece surface or edge. The purpose of surfacing, not for connecting parts, but called as parts strengthening and repair in surface engineering.

Repair refers to restore the original size of a part or increase the size of it.
Strengthening refers to change the property of the parts surface, the was given a special performance.

Deposited metal layer is different from thermal spraying coatings layer, there will be a fusion layer between surfacing layer and the substrate during welding process, which belongs to the metallurgy combination and has a high bonding strength, the surfacing layer thickness ranges from a few millimeters to tens of millimeters (3mm to 12mm), structure property and structure will be changed due to the heat influence on the matrix.

The mechanical property of metal materials is determined by the chemical composition and characteristics of micro-structure , therefore, the deposited weld metal composition and micro-structure has an important influence on wear resistance future of chromium carbide overlay plate.

Hardfacing alloy system and the organization can be classified as: iron-based alloys (including pearlitic steel, austenitic steel, martensitic steel and alloy Jin Tie), nickel base alloy,cobalt based alloy,copper base alloy and hard alloy (tungsten carbide) etc.