Roller shell hard coating
AssigneeIngersoll-Rand Company
InventorBani Ranjan Banerjee
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Abstract
Invention covers a method of hard surfacing machine parts, specifically the invention discloses a method of impregnating the surface of cylindrical pellet mill roller shells with tungsten carbide particles applied with a tungsten inert gas welding process. In the method of this invention, the surface layer of the roller shell is first carbon enriched by surface gas carburizing prior to welding. The resulting surface exhibits good distribution of tungsten carbide particles and resistance to surface cracking.
Claims12
A method of hard surfacing a steel roller which comprises:
- carburizing the steel surface of the roller to a depth equal to at least half the depth of the hard surfacing required;
- applying hard surfacing particles by immersing them in a weld puddle formed on the steel surface from the steel itself by a non consumable gas metal arc welding puddle process so that a uniform dispersion of particles is present in the weld whereby a high effective hardness within the entire thickness of the weld is obtained;
- and
- heat treating the weld to achieve the required properties of base and surface structures.
The method of applying a hard surface layer to a carburizing grade of low alloy steel comprising:
- precarburizing the surface by means of an endothermic gas atmosphere to accomplish a 0.8 percent surface carbon enrichment;
- producing a weld puddle from the steel itself on the steel surface approximately twice the depth of precarburization by means of a non consumable tungsten inert gas welding process;
- introducing into the weld puddle hard surface particles with controlled size and particle composition so as to form a uniform dispersion of said particles within said weld puddle so that a high effective hardness within the entire weld is obtained;
- and
- post weld heat treating the resulting surface to achieve the required hardness.
Dependencies are inferred from the claim text.