Recovery heat treatment of highly strained components

Abstract

A method of recovery heat treatment of a workpiece includes contacting at least a portion of the workpiece with a fluid heated to a temperature sufficient to heat the at least a portion of the workpiece to a predetermined temperature range in a predetermined time period. The method may be implemented as a first step of a two-stage recovery heat treatment or annealing process, followed by a second step of heating the at least a portion of the workpiece to a final target temperature by another annealing process.

What is claimed: 
     
         1 . A method of recovery heat treatment, comprising contacting at least a portion of a workpiece with a fluid heated to a temperature sufficient to heat the at least a portion of the workpiece to a predetermined annealing temperature range in a predetermined time period. 
     
     
         2 . The method of  claim 1 , wherein the workpiece comprises an aluminum alloy. 
     
     
         3 . The method of  claim 2 , wherein the aluminum alloy is selected from the group consisting of an AA6082 aluminum alloy, an AA6061 aluminum alloy, an AA6063 aluminum alloy, an AA6111 aluminum alloy, an AA6022 aluminum alloy, an AA6016 aluminum alloy, an AA5754 aluminum alloy, or an AA5182 aluminum alloy. 
     
     
         4 . The method of  claim 1 , wherein the workpiece is a bent and/or pre-formed vehicle frame rail or a formed sheet metal workpiece. 
     
     
         5 . The method of  claim 1 , including contacting only a formed portion of the workpiece with the fluid. 
     
     
         6 . The method of  claim 1 , wherein the fluid is a liquid. 
     
     
         7 . The method of  claim 1 , wherein the fluid comprises a finely divided particulate solid. 
     
     
         8 . The method of  claim 6 , wherein the liquid is selected from the group consisting of an oil, a lubrication oil, a quenching oil, a heating oil, a synthetic oil, a semi-synthetic oil, a mineral oil, water, a water-oil emulsion, a polymer water, oil based solutions and emulsions, a molten salt, an alkali salt, and combinations thereof. 
     
     
         9 . A method of recovery heat treatment of a workpiece, comprising:
 heating at least a portion of the workpiece to a first, intermediate temperature range in a predetermined time period; and   heating the at least a portion of the workpiece to a second, annealing temperature range in a predetermined time period.   
     
     
         10 . The method of  claim 9 , wherein the workpiece comprises an aluminum alloy. 
     
     
         11 . The method of  claim 10 , wherein the aluminum alloy is selected from the group consisting of an AA6082 aluminum alloy, an AA6061 aluminum alloy, an AA6063 aluminum alloy, an AA6111 aluminum alloy, an AA6022 aluminum alloy, an AA6016 aluminum alloy, an AA5754 aluminum alloy, or an AA5182 aluminum alloy 
     
     
         12 . The method of  claim 9 , wherein the workpiece is a bent and/or pre-formed vehicle frame rail or a formed sheet metal workpiece. 
     
     
         13 . The method of  claim 9 , including contacting the at least a portion of the workpiece with a fluid heated to a temperature sufficient to heat the at least a portion of the workpiece to the first, intermediate temperature range. 
     
     
         14 . The method of  claim 13 , including contacting only a formed portion of the workpiece with the fluid. 
     
     
         15 . The method of  claim 13 , wherein the fluid is a liquid. 
     
     
         16 . The method of  claim 13 , wherein the fluid comprises a finely divided particulate solid. 
     
     
         17 . The method of  claim 15 , wherein the liquid is selected from the group consisting of an oil, a lubrication oil, a quenching oil, a heating oil, a synthetic oil, a semi-synthetic oil, a mineral oil, water, a water-oil emulsion, a polymer water, oil based solutions and emulsions, a molten salt, an alkali salt, and combinations thereof. 
     
     
         18 . The method of  claim 9 , including heating the at least a portion of the workpiece to the first, intermediate temperature range by one or more heating elements. 
     
     
         19 . The method of  claim 18 , wherein the one or more heating elements are infrared heating elements. 
     
     
         20 . The method of  claim 19 , including heating the at least a portion of the workpiece to the second, annealing temperature range by an induction annealing process.