Production of high temperature articles and alloys therefor

Claim 1

A METHOD OF IMPROVING THE RESISTANCE TO CREEP OF AN ALLOY CONSISTING ESSENTIALLY OF FROM 10 TO 25% CHROMIUM, 1.8 TO 4.0% TITANIUM, 0.5 TO 4% ALUMINIUM, UP TO 25% COBALT, UP TO 10% IRON, CARBON IN AN AMOUNT WITHIN THE RANGE DEFINED BY THE INTERSECTION OF THE ORDINATE CORRESPONDING TO THE COBALT CONTENT WITH THE LINES A AND B SHOWN IN FIGURE 1 OF THE ACCOMPANYING DRAWINGS, AND THE BALANCE NICKEL, EXCEPT FOR IMPURITIES AND RESIDUAL DEOXIDANTS, WHICH COMPRISES FIRST HEATING THE ALLOY AT A TEMPERATURE OF FROM 1150 TO 1250* C. WITH THE DURATION OF THIS HEATING STEP BEING FROM 2 TO 12 HOURS AT 1150* C. AND FROM 1/2 TO 4 HOURS AT 1250* C. AND WITH INTERMEDIATE PERIODS AT INTERMEDIATE TEMPERATURES SUBSEQUENTELY HEATING THE ALLOY FOR AT LEAST TWO HOURS AT A TEMPERATURE WHICH DOES NOT EXCEED ABOUT 1100* C. AND IS NOT LESS THAN ABOUT 800* C. AND WHICH IS CORRELATED TO THE CARBON AND COBALT CONTENTS IN ACCORDANCE WITH FIGS. 4, 5 AND 6 OF THE ACCOMPANYING DRAWING, AND THEREAFTER HOLDING THE ALLOY FOR FROM 1 TO 24 HOURS AT A TEMPERATURE WHICH IS WITHIN THE RANGE 650 TO 850* C. BUT IS IN ANY CASE LOWER THAN THE TEMPERATURES OF THE PRECEDING HEATING STEPS, WHEREBY A HEATTREATED ALLOY IS OBTAINED CHARACTERISED BY HAVING IMPROVED FRACTURE LIFE AT ELEVATED TEMPERATURES.

Claim 2

A METHOD OF IMPROVING THE RESISTANCE TO CREEP OF AN ALLOY CONSISTING ESSENTIALLY OF FROM 10 TO 25% CHROMIUM, 1.8 TO 4.0% TITANIUM, 0.5 TO 4% ALUMINIUM, UP TO 25% COBALT, UP TO 10% IRON, CARBON IN AN AMOUNT WITHIN THE RANGE DEFINED BY THE INTERSECTION OF THE ORDINATE CORRESPONDING TO THE COBALT CONTENT WITH THE LINES A AND B SHOWN IN FIGURE 1 OF THE ACCOMPANYING DRAWINGS, AND THE BALANCE NICKEL, EXCEPT FOR IMPURITIES AND RESIDUAL DEOXIDANTS, WHICH COMPRISES FIRST HEATING THE ALLOY AT A TEMPERATURE OF FROM 1150 TO 1250* C. WITH THE DURATION OF THIS HEATING STEP BEING FROM 2 TO 12 HOURS AT 1150* C. AND FROM 1/2 TO 4 HOURS AT 1250* C. AND WITH INTERMEDIATE PERIODS AT INTERMEDIATE TEMPERATURES SUBSEQUENTELY HEATING THE ALLOY FOR AT LEAST TWO HOURS AT A TEMPERATURE WHICH DOES NOT EXCEED ABOUT 1100* C. AND IS NOT LESS THAN ABOUT 800* C. AND WHICH IS CORRELATED TO THE CARBON AND COBALT CONTENTS IN ACCORDANCE WITH FIGS. 4, 5 AND 6 OF THE ACCOMPANYING DRAWING, AND THEREAFTER HOLDING THE ALLOY FOR FROM 1 TO 24 HOURS AT A TEMPERATURE WHICH IS WITHIN THE RANGE 650 TO 850* C. BUT IS IN ANY CASE LOWER THAN THE TEMPERATURES OF THE PRECEDING HEATING STEPS, WHEREBY A HEATTREATED ALLOY IS OBTAINED CHARACTERISED BY HAVING IMPROVED FRACTURE LIFE AT ELEVATED TEMPERATURES.