1. Corrosion Resistance of P/M S.St.
Richard R. Phillips,
Engineered Pressed Materials
Dennis Hammond
Apex Advanced Technologies, LLC

2. Objective Using 316L, 17-4ph, 409LCb & 434L Achieve higher densities
Higher densities at lower sintering temperatures
Obtain good corrosion resistance

3. History Historically difficult to get high density
Compressibility limiting factor
Work hardening during pressing
High surface oxides on powder
Limited oxide reduction in sintering and densification
Lower densities interferes with corrosion resistance

4. Water atomized 316L
3200 ppm O2
5200X

5. Gas atomized 316L
150 ppm O2
5200X

6. Powder Preparation
100 mesh standard powders of 316L, 17-4ph, 409LCb & 434L
A group with 0.75 % Lithium Stearate
A group with an Activation Technology
TRS bars pressed at 690 Mpa (50TSI)

7. Activation Technology
Blend Additive/Lubricant Master Batch
Hydrostatic distribution of additives & lubricant during compaction
Particles are aligned in a best fit arrangement
Density gradients eliminated
Activation is initiated in the delubing stage and finalized in the early stage of sintering

8. Density Gradient – Shape Retention
EPM

9. Lithium stearate Activation Technology

10. Compressibility g/cm3 at 690 Mpa (50TSI)
Material Li Str Activation
316L
17-4ph
409LCb
434L

11. Processing TRS bars delubed at 400OC (750OF) in Air
Sintering in a H2 box furnace with a slow cool > 1 hr.
Sintering in a continuous vacuum furnace with a 2 bar fast N2 quench < 10 min.
Sintered at: 1120 (2050), 1177 (2150), 1232 (2250), 1288 (2350), 1343 (2450) & 1388OC (2530OF)
Time at temperature 45 min.

12. Atmosphere Box Furnace

13. Continuous Vacuum N2 quench

14. Sintering size change and densification

33. ASTM B895 Standard for Test Method 2
For alloy screening and process optimization

34. D X C B A 0%A, <1%B, 1-25%C, >25%D 744 hrs. immersion in 5% NaCl
316L ¢C (¢F)
(2050)
(2150)
1232 (2250)
(2350)
(2450)
(2530)
Li Str ATMO D X C B
Activ. ATMO A
Li Str VAC
Activ. VAC
0%A, <1%B, 1-25%C, >25%D
744 hrs. immersion in 5% NaCl

35. C X B A D 0%A, <1%B, 1-25%C, >25%D 744 hrs. immersion in 5% NaCl
17-4PH ¢C (¢F)
(2050)
(2150)
1232 (2250)
(2350)
(2450)
(2530)
Li Str ATMO C X B
Activ. ATMO A
Li Str VAC D
Activ. VAC
0%A, <1%B, 1-25%C, >25%D
744 hrs. immersion in 5% NaCl

36. D X C A B 0%A, <1%B, 1-25%C, >25%D 744 hrs. immersion in 5% NaCl
409Cb ¢C (¢F)
(2050)
(2150)
1232 (2250)
(2350)
(2450)
(2530)
Li Str ATMO D X C
Activ. ATMO A
Li Str VAC B
Activ. VAC
0%A, <1%B, 1-25%C, >25%D
744 hrs. immersion in 5% NaCl

37. D X C B 0%A, <1%B, 1-25%C, >25%D 744 hrs. immersion in 5% NaCl
434L OC (¢F)
(2050)
(2150)
1232 (2250)
(2350)
(2450)
(2530)
Li Str ATMO D X C
Activ. ATMO B
Li Str VAC
Activ. VAC
0%A, <1%B, 1-25%C, >25%D
744 hrs. immersion in 5% NaCl

38. 0%A, <1%B, 1-25%C, >25%D
744 hrs. immersion in 5% NaCl

39. 0%A, <1%B, 1-25%C, >25%D
744 hrs. immersion in 5% NaCl

40. 0%A, <1%B, 1-25%C, >25%D
744 hrs. immersion in 5% NaCl

41. 0%A, <1%B, 1-25%C, >25%D
744 hrs. immersion in 5% NaCl

42. BETTER CORROSION RESISTENCE
Conclusion
BETTER CORROSION RESISTENCE
Higher density
Faster cooling rate
Activation Technology
Higher density at a lower temperature
` Better response with continuous Vacuum
Best corrosion resistance