Mohammad Irfan, David Schwam (CWRU) Andy Karve, Randy Ryder (Neemak) Mike Cox, John Kubisch (GM)

1. nadca meetingdie casting mechanical property improvements through process enhancementsmid term progress report Mohammad Irfan, David Schwam (CWRU) Andy Karve, Randy Ryder (Neemak) Mike Cox, John Kubisch (GM) February, 2009

2. Outline • Part I: Review of Project Brief • Part II: Initial Trials • Part III: EDX & SEM • Part IV: Introduction of cooling core • Part V: DOE • Conclusions • Future Work

3. Review of project brief Part - I

4. Review of Project Brief • DOE setup to understand the effect of Process Parameters on Mechanical Properties of thickest section • Process Parameters: • Melt Handling : Melt Temperature, Pour Temperature • Injection: Slow shot velocity. Fast shot velocity, intensification pressure • Solidification: Die Temperature, Temperature of casting at ejection, Cycle time • Water Quench • T5 heat treatment

5. Gantt Chart Sept Oct Nov Dec Jan Feb Mar Apr May Jun Project Kick-off DOE Process Testing Metall. & Mech. Testing Process Testing Metall. & Mech. Testing Final Report

6. Initial trialsford v6 engine blocks Part - II

7. Sampling • Test specimens were taken from the center saddles on the underside of the block as indicated in the figure. Three specimens were taken from each saddle with two specimens coming from the edges of one side of the saddle and one specimen from the center of the opposite side.

8. Percentage Pore Area Vs. Yield Strength

9. Percentage Pore Area Vs. Tensile Strength

10. Percentage Pore Area Vs. Elongation

11. DAS vs. UTS (Strong Dependence) FORD SPEC. 175 MPa

12. DAS vs. YS (Weak Dependence) FORD SPEC. 170 MPa

13. DAS vs. Elongation FORD SPEC. 0.5 %

14. Conclusions from initial trials • It is hard to relate mechanical properties with % area porosity • It does not mean that porosity does not effect mechanical properties. Efforts should be continued to minimize porosity. • DAS seems to be a better indicator of mechanical properties • Future efforts should be directed towards improving DAS

15. Edx and sem Part - III

16. Broad spectrum SEM micrograph

17. EDX – Material composition (Magnification 5000x) Cu rich zones Iron rich β phase Si Needles

18. SEM : Sample ford v6 block Micro porosity Crack Dimpled Fracture Surface Large Pore

19. SEM: porosity Inclusion

20. HYUNDAI I-4-fractograph Cleavage fracture Limited Ductility (Dimples)

21. HYUNDAI I-4- fractograph Transgranular brittle fracture of Fe rich β phase Limited Ductility (Dimples) Cleavage fracture

22. Conclusions from EDX & sem • The EDX and SEM gave us a better picture of the microstructure of the die castings • Plate-like Fe rich β phase is known to act as obstruction to liquid metal flow • Cu rich “sludge” is known to act as porosity initiation sites • Fracture surface was in general “Cleavage” (brittle) with limited indications of ductility • Large pores acted as crack initiation sites during tensile tests

23. INTRODUCTION OF cooling core Part - IV

24. Cooled core 38407 Hyundai theta: 4 cylinder engine blocks • Two engine blocks, one with a cooled core and other with an un-cooled core • 5 journals from each engine block • Journal 3 was sent sliced in the middle for measuring DAS across the face • Journals 1,2,4,5 were cut further to extract 2 tensile samples from each journal Un-cooled core 38406

25. 38406 – journal -3

26. 38407-j3-mid section3-o’clock measurements • Measurements starting from edge of hole (cooling core) every 1.5 mm till 15 mm (11 measurements). Then measurements every 3 mm till the right sectioned edge 12 mm (4 measurements)

27. Das vs. distance from cooling core (3 O’ CLOCK) y = mx +c DAS = 0.5 x + 18 Initial Value

28. 38407-j3-mid section9-o’clock measurements • Measurements starting from edge of hole (cooling core) every 1.5 mm till 13.5 mm (10 measurements).

29. Das vs. distance from cooling core (9 O’ CLOCK)

30. 38407-j3-mid section6-o’clock measurements • 10 Measurements starting from edge of hole (cooling core) every 1.1 mm till 10 mm. • 2 Measurements every 2.2 mm for 4.4 mm. • 3 measurements every 1.1 mm starting from the bottom journal edge for 3.3 mm

31. Das vs. distance from cooling core 6 O’CLOCK Core side Journal side • Note: Cooling is not a 1 Dimensional Problem • The cooling effect measured in terms of DAS is a 3 D problem, with heat transfer taking place in all 3 directions • Solidification starts both at the core and journal ends, giving the minimum DAS

32. 38407-j3-right section3-o’clock measurements CORE EXTERNAL EDGE

33. Das vs. distance from cooling core (3 O’ CLOCK) TILL AS-CAST EDGE CORE EXTERNAL EDGE

34. COOLED CORE DAS MEASURED IN TENSILE SAMPLES UN COOLED CORE

35. DAS B034: Cooled, No TiBor, Short Dwell, Quench E B040: Un-Cooled, TiBor, Long Dwell, Quench W

36. comparing effects of block size and core presence Hyundai- I-4 38407 cooled core Wt: 22.7 kg

38. H13 Toolox 44 Anvilloy 3C CuBe

42. DOE Part - V

43. Doe matrix : L8 FACTORIAL

44. Process parameters for b034 & b040

45. Tensile Properties – B034 & B040 B040: Un-Cooled, TiBor, Long Dwell, Quench W B034: Cooled, No TiBor, Short Dwell, Quench E

46. Conclusions • The water cooled core reduces DAS and improves mechanical properties, however the cooling effect fades with increasing distance from the core • Higher cooling rates and deeper penetration can be achieved by using cores made of higher thermal conductivity alloys and/or higher flow rates • The grain refined engine block with no-cooling exhibited a fine DAS and improved mechanical properties • From our previous presentations, DAS can effectively be used as a predictor of Mechanical properties (Strong dependence: UTS & Elongation, Weak dependence: YS) • % Pore area is not a reliable predictor of mechanical properties due to the probabilistic and random nature of porosity at the section under observation

47. Future work • Continue with DOE analysis • Report Writing

48. Thank You Questions ?