Method for Joining Dispersion-Strengthened Alloy

Abstract

The present invention relates to a method for joining two or more components and/or construction parts, at least one of which consists of a dispersion-strengthened alloy having the following composition (in % by weight): C up to 0.08 Si up to 0.7 Cr 10-25 Al 1-10 Mo 1.5-5 Mn up to 0.4 balance Fe as well as normally occurring impurities by the fact that the cross section in the joint is enlarged by forging before joining and where the product manufactured according to the method can be used in high-temperature applications at temperatures above 900° C.

1 . Method for joining one or more construction parts, at least one of the parts consisting of a dispersion-strengthened alloy, comprising enlarging by forging a cross section in the joint before joining. 
     
     
         2 . Method for joining one more construction parts according to  claim 1 , wherein the dispersion-strengthened alloy has a composition comprising (in % by weight):
 C up to 0.08   Ci up to 0.7   Cr 10-25   Al 1-10   Mo 1.5-5   Mn up to 0.4   balance Fe as well as normally occurring impurities.   
     
     
         3 . Construction part manufactured according to method according to  claim 1  for use in high-temperature applications at temperatures above 900° C. 
     
     
         4 . Construction part manufactured according to the method according to  claim 1  for use in cracking furnaces. 
     
     
         5 . Construction part manufactured according to the method according to  claim 1 , where a creep rupture criterion σ==F 1 /A 1  in the joint is increased by cross-section enlargement. 
     
     
         6 . A method for joining a first tube to a second tube, the method comprising:
 enlarging a first end of the first tube by forging to increase a cross-sectional area of a tube wall at the first end; and   welding the enlarged first end to the second tube,   wherein the first tube is formed from a dispersion strengthened alloy.   
     
     
         7 . The method of  claim 6 , wherein the dispersion strengthened alloy has a composition comprising (in % by weight):
 C up to 0.08   Ci up to 0.7   Cr 10-25   Al 1-10   Mo 1.5-5   Mn up to 0.4   balance Fe as well as normally occurring impurities.   
     
     
         8 . The method of  claim 6 , wherein welding the enlarged first end to the second tube forms a joint and wherein a creep rupture criterion σ=F 1 /A 1  in the joint is increased by cross-section enlargement. 
     
     
         9 . The method of  claim 6 , wherein enlarging the first end of the first tube is by forging. 
     
     
         10 . The method of  claim 6 , wherein enlarging the first end of the first tube is by turning or by HIP-ing. 
     
     
         11 . The method of  claim 6 , wherein the cross-sectional area is increased by an amount that at least corresponds to a load decrease. 
     
     
         12 . The method of  claim 6 , wherein the first tube is a radiant tube in a cracking furnace.