Scan and single-shot induction hardening were used to harden 1045 and 10V45 steels. Torsional fatigue testing found that while case hardness was higher in 10V45, 1045 exhibited greater ductility during crack propagation, leading to improved fatigue life. Scan hardening produced a finer prior austenite grain size and lower residual stresses than single-shot hardening. However, fatigue performance was similar between the two processes at 550 MPa stress amplitude, with single-shot showing 70% higher life at 650 MPa.
Microstructural and Torsional Fatigue Characteristics of Singleshot and Scan Induction Hardened 1045 and 10V45 Steels
1. 1
Microstructural and Torsional
Fatigue Characteristics of Single-
shot and Scan Induction Hardened
1045 and 10V45 Steels
Lee Rothleutner1, Jody Burke2,
Dr. Chester J. Van Tyne1, and Robert Cryderman1
1Advanced Steel Processing and Products Research Center
Colorado School of Mines, Golden, CO 80401 USA
2Gerdau Special Steel North America, Jackson, MI 49201 USA
Additional support from Rob Goldstein of Fluxtrol Inc.
as well as Rob Madeira and Jeff Elinski of Inductoheat Inc.
2. 2
Study Design
Induction hardened shaft ...
Performance
↑ Strength
↑ Fatigue life
1. High case depth
2. Favorable case
microstructure
3. Favorable residual
stress profile
Processing
• Power
• Frequency
• Quenchant
(conc. & flow rate)
• Coil design
• Scan speed
3. 3
Study Design
Scope...
• Scan vs. Single-shot induction hardened
– Effective case depth of 44% (~70% of area)
– 1045 and 10V45 (F/P starting microstructure)
Outline...
1. Case microstructure
2. Residual stresses (near surface)
3. Torsional fatigue performance
(550, 600, 650 MPa stress amplitude, R=0.1)
4. 4
Materials – Chemistry
wt pct C Mn Si Ni+Cr+Mo V Al N P S Cu DIb (mm)
1045 0.44a 0.74 0.23 0.25 0.002 0.016 0.0068 0.010 0.006 0.26 35.6
10V45 0.47a 0.82 0.28 0.24 0.080 0.007 0.0100 0.007 0.009 0.22 45.5
Minc 0.43 0.60 --- --- --- --- --- --- --- --- ---
Maxc 0.50 0.90 --- --- --- --- --- 0.040 0.050 --- ---
a Standard Deviation of 0.01 wt pct (n = 5)
b ASTM A255-10: Standard Test Methods for Determining Hardenability of Steel
c ASTM A29-12: Standard Specification for General Requirements for Steel Bars, Carbon and Alloy, Hot-Wrought
Hot Rolled to 39.7 mm (1.563 in) Diameter Bar (18.8 to 1)
14. 14
Case Microstructure
Depth from
Surface
Scan Single-shot
1045 10V45 1045 10V45
0.0 mm --- --- --- R
0.5 mm --- R + T R R + T
0.0 mm
0.5 mm
10V45...
Higher tendency for non-martensitic
transformation products both retained (R)
and transformed (T) ferrite.
No ghost pearlite was observed within
0.5 mm of surface in any condition.
10V45-Single
10V45-Single
15. 15
Case Microstructure – PAGS
1045-Scan
10V45-Single
10V45 is not significantly different from
1045 for a given processing routine.
26. 26
Thank you for your attention!
Lee M. Rothleutner
lrothleu@mines.edu
27. 27
Residual Stress
• Incremental Hole Drilling Method
– ASTM E837
– Type A strain gage rosette.
– Inverted cone diamond mill.
– Strain measured every 0.05
mm to 1 mm.
– H-DRILL (v3.11) software
• Prof. Gary Schajer (UBC)
Hoop
Axial
Diamond
Mill
Micrometer
Head
Air Turbine
Assembly
Light
•Vishay M-M
•RS-200
X & Y
Adjustment
28. 28
Net Stress
- 𝜎 𝑦
𝑠
-𝜎𝑥
𝑠
𝜏 𝑥𝑦
𝑠
Residual
Stress State
Applied
Stress State
Net
Stress State
Resultant
Principal
Stresses
𝜎
𝜏
+
−𝜏 𝑥𝑦
𝑟𝑒𝑠
- 𝜎 𝑦
𝑟𝑒𝑠
-𝜎𝑥
𝑟𝑒𝑠 -𝜃
𝜎1
-𝜎2
=
𝜏 𝑥𝑦
𝑎𝑝𝑝
𝜎
𝜏
+ =𝜎
𝜏
𝜎
𝜏
=
=
29. 29
Net Stress
Maximum Reduction in Applied Stress
-𝜃
𝜎1
-𝜎2
Positive throughout test.
Negative throughout test.
Between -30° (at min)
and -45° (at max).
-𝜎2
𝜎1
-𝜃
10V45 is not significantly different from
1045 for a given processing routine.
(MPa) Scan Single-shot
650 -400 -560
550 -400 -560
𝝈1