Method for forming components of track-type machines having a metallurgically bonded coating

Abstract

Undercarriage assembly components of track-type machines having a metallurgically bonded wear-resistant coating and methods for forming such coated undercarriage assembly components is disclosed herein. The bodies of the undercarriage assembly components, formed of an iron-based alloy, have a hard metal alloy slurry disposed on a surface or into an undercut or channel and then fused to form a metallurgical bond with the iron-based alloy. The wear-resistant coating comprises a fused, metal alloy comprising at least 60% iron, cobalt, nickel, or alloys thereof. The portion of the outer surface of the undercarriage assembly components having the wear-resistant coating corresponds to a wear surface of the component during operation of the endless track of the track-type vehicle.

What is claimed is: 
     
         1 . A method of making a pin bushing joint, the method comprising:
 forming a bushing including an outer surface having an outer diameter and including an inner surface having an inner diameter;   forming a track pin including an outer surface substantially conforming to a portion of the inner surface of the bushing, wherein the inner surface of the bushing and the outer surface of the track pin form a wear surface;   removing portions of the wear surface from the inner surface of the bushing to expose an area of the bushing to be coated and removing portions of the wear surface from the outer surface of the track pin to expose an area of the track pin to be coated;   coating the exposed area of both the bushing and the track pin with a slurry comprising a fusible, hard metal alloy with at least 60% by weight of iron, cobalt, nickel or alloys thereof in the form of a finely divided powder, polyvinyl alcohol, a suspension agent and a deflocculant; and   forming a metallurgical bond between the exposed area and the coating slurry to form a wear-resistant coating.   
     
     
         2 . The method of  claim 1 , further comprising adjusting the thickness of the slurry so that the final wear-resistant coating is flush with adjacent unremoved areas of the bushing and the track pin. 
     
     
         3 . The method of  claim 1 , wherein the step of forming a metallurgical bond comprises drying the coated slurry, heating the coated body to a fusion temperature of the fusible, hard metal alloy in a controlled atmosphere of at least one inert gas or reducing atmosphere excluding nitrogen, and cooling the coated body to ambient temperature. 
     
     
         4 . The method of  claim 1 , wherein the bushing and the track pin are formed of a medium carbon steel. 
     
     
         5 . The method of  claim 1 , comprising removing portions of the outer surface of the bushing to expose a second area of the bushing to be coated;
 coating the exposed second area of the bushing with a slurry comprising a fusible, hard metal alloy with at least 60% by weight of iron, cobalt, nickel or alloys thereof in the form of a finely divided powder, polyvinyl alcohol, a suspension agent and a deflocculant; and   forming a second metallurgical bond between the exposed second area and the coating slurry to form a second wear-resistant coating.   
     
     
         6 . A method of making an undercarriage track chain bottom roller, the method comprising:
 forming a roll body having at least one cylindrical portion and at least one flange portion;   removing the outer surface of those portions of the said cylindrical and flange portions subject to wear to expose an area of the roller body to be coated;   coating the exposed area with a slurry comprising a fusible, hard metal alloy with at least 60% by weight of iron, cobalt, nickel or alloys thereof in the form of a finely divided powder, polyvinyl alcohol, a suspension agent and a deflocculant; and   forming a metallurgical bond between the exposed area and the coating slurry to form a wear-resistant coating.   
     
     
         7 . The method of  claim 6 , further comprising adjusting the thickness of the slurry so that the final wear-resistant coating is flush with adjacent unremoved areas of the said cylindrical and flange portions. 
     
     
         8 . The method of  claim 6 , wherein the step of forming a metallurgical bond comprises drying the coated slurry, heating the coated body to a fusion temperature of the fusible, hard metal alloy in a controlled atmosphere of at least one inert gas or reducing atmosphere excluding nitrogen, and cooling the coated body to ambient temperature. 
     
     
         9 . The method of  claim 6 , wherein the said roller body is formed of a medium carbon steel. 
     
     
         10 . A method of making a track chain link, the method comprising:
 forming the track chain link, the track chain link including a body, a mounting surface on a first edge of the body, and a contact surface on a second edge of the body, wherein the mounting surface includes at least one opening for an attachment device, the contact surface includes a substantially planar region extending a distance along the second edge forming a wear surface, and the contact surface is opposite the mounting surface;   removing portions of the wear surface to expose an area of the track chain link to be coated;   coating the exposed area of the track chain link with a slurry comprising a fusible, hard metal alloy with at least 60% by weight of iron, cobalt, nickel or alloys thereof in the form of a finely divided powder, polyvinyl alcohol, a suspension agent and a deflocculant; and   forming a metallurgical bond between the exposed area and the coating slurry to form a wear-resistant coating.   
     
     
         11 . The method of  claim 10 , further comprising adjusting the thickness of the slurry so that the final wear-resistant coating is flush with adjacent unremoved areas of the contact surface. 
     
     
         12 . The method of  claim 10 , wherein the step of forming a metallurgical bond comprises drying the coated slurry, heating the coated body to a fusion temperature of the fusible, hard metal alloy in a controlled atmosphere of at least one inert gas or reducing atmosphere excluding nitrogen, and cooling the coated body to ambient temperature. 
     
     
         13 . The method of  claim 10 , wherein the body is formed of hardened steel 
     
     
         14 . The method of  claim 10 , wherein the body is formed of a medium carbon steel. 
     
     
         15 . The method of  claim 10 , further comprising hardening the coated track chain link by quenching and tempering. 
     
     
         16 . The method of  claim 10 , further comprising hardening a portion of the body below the wear resistant coating by induction hardening, wherein a hardness of the hardened portion is HRC 50 to 55.