NICKEL BASE SUPER HEAT RESISTANT ALLOY AND HEAT TREATMENT BEFORE WELDING, AND WELDING FOR THIS NICKEL BASE SUPERALLOY

摘要

PROBLEM TO BE SOLVED: To adapt this invention not only to use in IN939 precipitation hardening nickel base super heat resistant alloys but also to use in the other precipitation hardening nickel base super heat resistant alloys in which welding is difficult or extremely low in welding suitability and to give advantages to these super heat resistant alloys from the viewpoint of imparting improved welding suitability to the super heat resistant alloys. SOLUTION: For this purpose, this invention contains a stage which is heat treatment before welding for a precipitation hardening nickel base super heat resistant alloy having a gamma matrix and a gamma 1st strengthening phase dispersed into the matrix, in which the nickel base super heat resistant alloy is heated at about 2120 deg.F for a time till the gamma 1st phase is melted, is thereafter slowly cooled to a temp. approximately lower than 1450 deg.F at a rate of =1 deg.F/min and is then cooled to a room temp. By the heat treatment before welding, at the time of obtaining the mechanical properties of the alloy after the subsequent heat treatment, the generation of strain aging cracks in the heat affected zone of base metal can be evaded.