BS in Materials Engineering
Materials Engineering Department
The ageing response for aluminum 2219-T6 was investigated to determine the effects a quench delay (QD) could have on tensile properties. Before testing commenced, furnace surveys were conducted to ensure they could meet the required temperature stability of + 10˚F (+6˚C). MIL-H-6088 specified a maximum quench delay of 15 seconds for parts thicker than 2.29 mm (0.090 in). An investigation was conducted on how different quench delay times changed the ageing response of T6 heat treated for Al 2219. Heat treatments were performed according to the ASM Handbook. Preliminary tests were performed on 1-1.5 in. cube blocks of Al 2219 and the ageing response was tracked using hardness. Later tests were conducted using flat tensile coupons. To relate the quench delay to the material temperature, cooling curves were made for the cubes and tensile samples. For the preliminary tests, quench delays of 15, 25, and 35 seconds were used which all yielded average hardness values ranging from 72-76 HRB and standard deviations ranging from 2-6 HRB. Using results from preliminary tests, the tensile samples had quench delays of 5, 10, 15, 20, and 25 seconds. There was a difference in yield and tensile strength for the samples with a 5 second QD when compared to samples with a 20 second and 25 second QD. To pass quality insurance the parts needed to have a yield strength above 276 MPa, tensile strength above 400 MPa, and elongation of 6% at 4 times the width of the samples. The yield strengths ranged from 271-315 MPa along with tensile strengths of 390-430 MPa. The ductility of the samples ranged from 15 to 18% elongation.