Lightweight, crash-sensitive automotive component
View Patent ↗The present invention provides a casting having increased crashworthiness including an an aluminum alloy of about 6.0 wt % to about 8.0 wt % Si; about 0.12 wt % to about 0.25 wt % Mg; less than or equal to about 0.35 wt % Cu; less than or equal to about 4.0 wt % Zn; less than or equal to about 0.6 wt % Mn; and less than or equal to about 0.15 wt % Fe, wherein the cast body is treated to a T5 or T6 temper and has a tensile strength ranging from 100 MPa to 180 MPa and has a critical fracture strain greater than 10%. The present invention further provides a method of forming a casting having increased crashworthiness.
1. A method of casting an aluminum alloy into a crash-sensitive automotive component having a desired critical fracture strain for collision impact, the method comprising:
selecting a crash-sensitive automotive component to cast;
providing a melt having an alloy comprising:
about 6.0 wt % to about 7.8 wt % Si;
about 0.10 wt % to about 0.18 wt % Mg;
less than or equal to about 0.35 wt % Cu;
less than or equal to about 0.6 wt % Mn;
less than or equal to about 0.15 wt % Fe;
and, a balance of aluminum and impurities;
casting the melt into a cast body of the crash-sensitive automotive component; and,
heat treating the cast body, the treating including a solution heating at 450° C. to 550° C. for about ½ hour to about 6 hours; quenching, and aging at a temperature of about 150° C. to about 250° C. for about ½ hour to about 10 hours;
wherein, the crash-sensitive automotive component has a critical fracture strain of at least about 10%.
2. The method of claim 1 , wherein the heat treating comprises processing to a T6 temper.
3. The method of claim 1 , wherein the processing comprises a solution heat treatment of the crash-sensitive automotive component at 450° C. to 550° C. for a time period ranging from approximately a ½ hour to approximately 6 hours, quenching, and aging; the processing creating a tensile yield strength in the cast body ranging from 190 MPa to 240 MPa.
4. The method of claim 1 , wherein the Mn content is less than 0.15 wt %, and the casting of the cast body includes using a vacuum riserless casting/pressure riserless process.
5. The method of claim 1 , wherein the casting of the cast body includes using a sand core in combination with a vacuum riserless casting/pressure riserless process to provide a wall thickness as thin as 2.0 mm.
6. The method of claim 1 , wherein the cast body is in T6 temper and has a tensile yield strength ranging from 100 MPa to 180 MPa.
7. The method of claim 1 , wherein the Mn content of the cast body is less than about 0.05 wt % Mn.
8. The method of claim 1 , wherein the heat treating comprises T6 or T7 to further provide an elongation that exceeds 14%.
9. The method of claim 1 , the melt having about 7.0 wt % Si and from about 0.10 wt % to about 0.18 wt % Mg.
10. The method of claim 1 , the melt having about 0.12 wt % Mg and from about 6.0 wt % to about 7.8 wt % Si.
11. A method of making a vehicle with a crash-sensitive automotive component having a desired performance during collision, the performance measured using critical fracture strain, the method comprising:
obtaining a crash-sensitive automotive component that was produced using a process including;
providing a melt having an alloy comprising:
about 6.0 wt % to about 7.8 wt % Si;
about 0.10 wt % to about 0.18 wt % Mg;
less than or equal to about 0.35 wt % Cu;
less than or equal to about 0.6 wt % Mn;
less than or equal to about 0.15 wt % Fe;
and, a balance of aluminum and impurities;
casting the melt into a cast body of the crash-sensitive automotive component; and,
heat treating the cast body, the heat treating including a solution heating at 450° C. to 550° C. for about ½ hour to about 6 hours; quenching, and aging at a temperature of about 150° C. to about 250° C. for about ½ hour to about 10 hours;
and,
employing the crash-sensitive component in the vehicle to provide a critical fracture strain of at least about 10% in the crash-sensitive component.
12. The method of claim 11 , wherein the crash-sensitive automotive component is a part of a vehicle frame construction.
13. The method of claim 11 , wherein the crash-sensitive automotive component is a part of a body structure.
14. The method of claim 11 , wherein the crash-sensitive automotive component is selected from a group consisting of a bracket, a node, a crashbox, a crossmember, a subframe, and an engine cradle.
15. The method of claim 11 , wherein the heat treating comprises processing the cast body to a T6 temper.
16. The method of claim 11 , wherein the heat treating comprises a solution heat treatment of the cast body at 450° C. to 550° C. for a time period ranging from approximately a ½ hour to approximately 6 hours, quenching, and aging; the processing creating a tensile yield strength in the cast body ranging from 190 MPa to 240 MPa.