HIGH-STRENGTH NODULAR IRON WITH GOOD WELDABILITY AND MACHINABILITY

• US 20200131606A1
• Filed: 10/30/2018
• Published: 04/30/2020
• Est. Priority Date: 10/30/2018
• Status: Active Application

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations LLC (General Motors Company)
• Inventors: Li, Huaxin, Yang, Jianghuai, Wilson, Daniel J., Gerard, Dale A., Zini, David M.
• Application Number:
  US16/174,443
• Publication Number:
  US 20200131606A1
• Time in Patent Office: Days
• CPC Class Codes: C22C 37/04 containing spheroidal graphite
• CPC Class Codes: C22C 37/08 with nickel
• CPC Class Codes: C22C 37/10 containing aluminium or silicon

Abstract

A nodular iron alloy and automotive components, such as differential and drive axle components, are provided. The nodular iron alloy may include iron, about 3.1-3.3 wt % carbon, about 2.7-4.3 wt % silicon, about 0.15-0.40 wt % manganese, about 0-0.10 wt % magnesium, about 0-0.2 wt % nickel, about 0-0.4 wt % copper, about 0-0.30 wt % chromium, about 0-0.03 wt % phosphorus, and about 0-0.02 wt % sulfur. The nodular iron alloy may have an ultimate tensile strength of at least 620 MPa as-cast. This alloy possesses favorable weldability to weld with steel components without substantial preheating or post heat treatment for a strong and tough weldment, and it has good machinability to facility comprehensive machining operations.

Claims

1. A nodular iron alloy comprising:

iron;

about 3.1 to about 3.3 weight percent carbon;

about 2.7 to about 4.3 weight percent silicon; and

about 0.15 to about 0.40 weight percent manganese.

2. The nodular iron alloy of claim 1, wherein the silicon is provided in an amount of about 3.5 to about 4.1 weight percent.

3. The nodular iron alloy of claim 2, wherein the iron is provided in an amount of at least 86.55 weight percent.

4. The nodular iron alloy of claim 3, further comprising magnesium in an amount not exceeding 0.10 weight percent.

5. The nodular iron alloy of claim 4, further comprising nickel in an amount not exceeding 0.2 weight percent.

6. The nodular iron alloy of claim 5, further comprising copper in an amount not exceeding 0.4 weight percent.

7. The nodular iron alloy of claim 6, further comprising chromium in an amount not exceeding 0.30 weight percent.

8. The nodular iron alloy of claim 7, further comprising sulfur in an amount not exceeding 0.02 weight percent.

9. The nodular iron alloy of claim 8, further comprising phosphorus in an amount not exceeding 0.03 weight percent.

10. The nodular iron alloy of claim 3, wherein the nodular iron alloy has an ultimate tensile strength greater than 620 MPa as-cast.

11. The nodular iron alloy of claim 10, having an elongation of greater than 6%.

12. The nodular iron alloy of claim 3, wherein the nodular iron alloy is substantially free of cobalt and molybdenum.

13. The nodular iron alloy of claim 11, wherein the iron is present in an amount of 65-85% of a ferrite microstructure and in an amount of 15-35% of a pearlite microstructure, wherein the iron surrounds a plurality of graphite nodules.

14. An automotive component created from a nodular alloy according to claim 3.

15. The automotive component of claim 14, wherein the automotive component is one of a differential component and a drive axle component.

16. A nodular iron alloy consisting essentially of:

about 3.1 to about 3.3 weight percent carbon;

about 2.7 to about 4.3 weight percent silicon;

about 0.15 to about 0.40 weight percent manganese;

0 to about 0.10 weight percent magnesium;

0 to about 0.2 weight percent nickel;

0 to about 0.4 weight percent copper;

0 to about 0.30 weight percent chromium;

0 to about 0.03 weight percent phosphorus;

0 to about 0.02 weight percent sulfur; and

the balance iron.

17. The nodular iron alloy of claim 16, wherein the silicon is provided in an amount of about 3.5 to about 4.1 weight percent.

18. The nodular iron alloy of claim 17, wherein the nodular iron alloy has an ultimate tensile strength greater than 620 MPa as-cast.

19. The nodular iron alloy of claim 18, the nodular iron alloy being substantially free of cobalt and molybdenum, wherein the iron is present in an amount of 65-85% of a ferrite microstructure and in an amount of 15-35% of a pearlite microstructure, and wherein the iron surrounds a plurality of graphite nodules.

20. An automotive component created from a nodular iron alloy according to claim 16.