Heat treatment method of alloy for eco-friendly vehicle parts

Abstract

Provided is a heat treatment method of an alloy for eco-friendly vehicle parts, the heat treatment method including preparing an aluminum (Al) alloy, performing solid solution treatment on the Al alloy, performing primary cooling to a temperature range of 250° C. to 400° C. after the solid solution treatment is performed, and performing secondary cooling to room temperature after the primary cooling is performed, wherein a cooling rate range of the primary cooling is lower than the cooling rate range of the secondary cooling.

What is claimed is: 
     
         1 . A heat treatment method of an alloy for eco-friendly vehicle parts, the heat treatment method comprising:
 preparing an aluminum (Al) alloy;   performing solid solution treatment on the Al alloy;   performing primary cooling to a temperature range of 250° C. to 400° C. after the solid solution treatment is performed; and   performing secondary cooling to room temperature after the primary cooling is performed,   wherein a cooling rate range of the primary cooling is lower than the cooling rate range of the secondary cooling.   
     
     
         2 . The heat treatment method of  claim 1 , wherein the cooling rate range of the primary cooling is 0.5° C./s to 10° C./s. 
     
     
         3 . The heat treatment method of  claim 1 , wherein the cooling rate range of the primary cooling is 0.5° C./s to 5° C./s. 
     
     
         4 . The heat treatment method of  claim 1 , wherein the cooling rate range of the secondary cooling is higher than 15° C./s. 
     
     
         5 . The heat treatment method of  claim 1 , wherein the cooling rate range of the secondary cooling is higher than or equal to 20° C./s. 
     
     
         6 . The heat treatment method of  claim 1 , wherein the cooling rate range of the secondary cooling is 20° C./s to 50° C./s. 
     
     
         7 . The heat treatment method of  claim 1 , wherein the solid solution treatment is performed in a temperature range of 450° C. to 540° C. 
     
     
         8 . The heat treatment method of  claim 7 , wherein the solid solution treatment is performed in the temperature range for a time exceeding 0 hour and not exceeding 12 hours. 
     
     
         9 . The heat treatment method of  claim 1 , wherein, in order not to be affected by thermal deformation, the primary cooling is performed in a cooling rate range in which a cooling curve by the primary cooling does not meet a portion of or intersect a time-temperature-transformation curve. 
     
     
         10 . The heat treatment method of  claim 1 , further comprising performing aging treatment on the Al alloy after the secondary cooling is performed. 
     
     
         11 . The heat treatment method of  claim 10 , wherein, after the aging treatment is performed, the Al alloy has a tensile strength of 290 MPa to 320 MPa, a yield strength of 235 MPa to 270 MPa, and an elongation of 8.5% to 12%.