Boronized laying pipe

Abstract

A laying pipe for use in the laying head of a rolling mill is configured for rotation about an axis, with an entry end aligned on that axis to receive a hot rolled product, and with a curved section leading to a delivery end spaced radially from that axis. The curved section defines a guide path configured to form the hot rolled product into a helical formation of rings. The laying pipe comprises a tubular ferrous wall having an interior surface comprising a wear resistant boronized layer against which the hot rolled product is confined for movement along the guide path. A method of enhancing the wear resistance of the laying pipe comprises forming a wear resistant boronized layer on at least one of the interior and exterior surfaces of said pipe.

We claim: 
     
         1 . A method of enhancing the wear resistance of a tubular metal laying pipe to a hot rolled product passing therethrough, comprising forming a wear resistant boronized layer on at least one of the interior and exterior surfaces of said pipe. 
     
     
         2 . The method of  claim 1 , wherein a wear resistant boronized layer is formed on both the interior and exterior surfaces of said pipe. 
     
     
         3 . The method of  claim 1 , wherein the metal of said pipe is selected from the group consisting of ferrous metals, nickel based alloys, titanium based alloys and cobalt based alloys. 
     
     
         4 . The method of  claim 1 , wherein said said boronized layer is the result of a thermochemical treatment in which boron atoms are diffused into the at least one of said surfaces. 
     
     
         5 . The method of  claim 4 , wherein the hardness of said pipe is between about 330 to 430 knoop (HK 100 ), and wherein said boronized layer has an increased hardness of between about 1600 to 2300 knoop (HK 100 ). 
     
     
         6 . The method of  claim 1 , wherein said laying pipe is shaped by a bending process comprising heating a straight tube to an elevated temperature of about 840° C. to 1050° C., bending the thus heated tube into a configuration having an entry end lying on an axis, with a curved section leading from said entry end to a delivery end spaced from said axis, and cooling the thus heated and bent tube to an ambient temperature, at least one of the surfaces of said laying pipe being defined by a boronized layer. 
     
     
         7 . The method of  claim 6 , wherein said boronized layer is formed on at least one of said surfaces of said pipe prior to said bending process. 
     
     
         8 . The method of  claim 6 , wherein said boronized layer is formed on at least one of said surfaces of said pipe following said bending process. 
     
     
         9 . The method of  claim 1 , wherein said laying pipe is fabricated as an assembly of an interior tubular metal wall enclosed within an exterior tubular metal wall, and wherein at least one of the interior and exterior surfaces of said interior and exterior tubular metal walls comprise wear resistant boronized layers.