What is the objective of the lab?
The objective of this lab is to investigate the effects of cold rolling on the strength of aluminum. Specifically, the lab aims to examine how various factors, such as annealing, cold work, and rolling pressure, influence the material’s mechanical properties. This will be done by rolling aluminum strips to different thicknesses and testing their tensile strength. The lab also focuses on understanding how the cold rolling process impacts the material’s reduction in thickness and the resulting strength, and how annealing may alter these effects.
What is the procedure of this lab? Part 1
- Prepare Aluminum Strips:
Cut 6.5” from each aluminum strip (A, B, C, D). Mark each strip accordingly.
Measure and record the length and width of the remaining strip.
Measure width at both ends for consistency. - Annealing:
Anneal strips B and D by placing them in the oven for 30 minutes at 650°F before use. Set aside and mark the 6.5” coupons as A0, B0, C0, and D0. - Zero the Rollers:
Zero the rollers against a fresh strip and ensure the strip stays centered. - Rolling (First Step):
Adjust the rollers to reduce the thickness to about 0.054”. Roll strip A and record the length, width, thickness, and the rolling force (strain gauge voltage).
Grease the strip lightly to reduce friction.
Note the rolling force and maintain the strip’s flatness as it exits the rollers. Pull with pliers to prevent warping. - Repeat Rolling for Strips A and B:
Repeat the rolling process for strip B (using the same settings).
What is the procedure of this lab? Part 2
- Adjust Roller for Second Step:
Set rollers to reduce thickness to 0.048” and roll all strips. Record data for each strip. - Subsequent Rolling (Continue Reducing Thickness):
Continue reducing thickness in stages as follows, recording length, width, and rolling force for each step:
Reduce thickness to 0.042” (step 3).
Reduce to 0.036” (step 4).
Reduce to 0.030” (step 5).
Reduce to 0.024” (step 6). - Tensile Specimen Preparation:
Use the Tensile Specimen Cutter to shape each strip into a 0.5” wide coupon.
Carefully align and cut the strips, ensuring smooth edges without stress concentrations. - Tensile Testing:
Test each coupon using the Tinius Olsen Tensile Testing Machine. Record the maximum tensile force for each coupon. - Finish the Experiment:
Clean up and ensure all data is recorded properly
What is the conclusion of this lab?
Conclusions
The experiment demonstrated that cold rolling increased the tensile strength and hardness of aluminum, even when the rollers were operated in reverse. Despite this adjustment, the material still showed typical cold rolling effects, such as thickness reduction and grain elongation, confirming that the process effectively enhances aluminum’s mechanical properties for industrial use.
