1. Laboratory for Multiphysics & Multiscale Systems
[2014 Fall Creative Capstone Design]
Predict Heat-Hardened area by ultrasonic method (unsettled)
Kwon, Jaehwan
Kim, Junhyung
Hyun, Seunghyeop
Kwon, Soonhyun 재료
Laboratory for Multiphysics & Multiscale Systems

2. Index Introduction 1.1 Importance of Hardness 1.2 To measure hardness
1.3 Limitation of Destructive Test
2. Theoretical Background
2.1 Phase
2.2 Hardening
3. Experiment Design
3.1 Objective of experiment
3.2 Define experiment data
4. Results and discussion
4.1 Results
4.2 Discussion
5. Conclusion
6. Reference
7. Appendix
7.1 Specification of ultrasonic tester

3. 1. Introduction 1.1 Importance of Hardness
Hardness guarantees to prevent
(1) Crack (2) Chip which is related to life of product
Crack causes
stress concentration
reduce the life
경도의 정의
Chip causes
debris
disturb the motion
Proper hardness should be guaranteed in manufacturing

4. we should destruct the sample to conduct the test
1. Introduction
1.2 To measure hardness
Hardness is quantified by the shape of indentation
Indent is to press the surface of material with tip
경도의 정의
Hardness tester
In this way, however,
we should destruct the sample to conduct the test

5. 1. Introduction 1.3 Limitation of Destructive test
Destructive test has many limitations
such as (1)money (2)time (3)sampling inspection
DWTT(Drop weight teat test)
To overcome the limitation of hardness test,
we selected ultrasonic test as a solution

6. Phase transition makes hardness different in same sample
2. Theoretical background
2.1 Phase
Phase is a homogeneous portion of a system that has uniform physical and chemical characteristics
[phase 1]
[phase 2]
Phase transition makes hardness different in same sample

7. 2. Theoretical background
2.2 Transformation Hardening
Transformation hardening is causing phase transition to make material harder
e.g) heat treatment
In steel, After heat treatment
much harder in heat treated area
(dark gray area)
less hard in matrix (light gray area)

8. We want to figure out the relation b/w the depth from ultrasonic test
3. Experiment Design
3.1 Objective of experiment
We want to figure out the relation b/w
the depth from ultrasonic test
and hardness information in hardened area

9. We measure three depths from three different source
3. Experiment Design
3.2 Define experiment data
We selected three source to measure depth
Ultrasonic depth
Depth from Ultrasonic tester
[Hardness results]
(2) Visual depth
Depth from color difference
(3) Hardened depth
Point where ΔHv>70Hv from hardness tester
We measure three depths from three different source

10. 4. Results and Discussion
Hardened depth, visual depth, Ultrasonic depth
Depth(mm)
At last comparing real, ultrasonic measured, and hardened depth.
Specimen #
Three depths are almost same !

11. 4. Results and Discussion
[unit: mm]
Specimen # 1 2 3 4 5 6 7 8
( a )
1.65
1.85
1.8
1.75
2.3
0.6
0.8
Visual depth ( b )
1.7
2.5
2.4
0.9
Ultrasonic depth ( c )
1.6
1.9
0.7 1 2 3 4 5 6 7 8
deviation
a-b
-0.05
0.05
0.1
-0.2
-0.1
0.0
0.09
a-c
0.15
b-c
0.2
0.11
At last comparing real, ultrasonic measured, and hardened depth.
deviation of (a-b) and (a-c) have similar value
(c-0.1) is almost same with (a)

12. Ultrasonic depth ≈ Hardened depth ≈ Visual depth
5. Conclusion
From experiment,
Ultrasonic depth ≈ Hardened depth ≈ Visual depth
(1) We can know hardened depth from ultrasonic test
without cutting the sample.
(2) Also, we confirmed that martensitic hardness is guaranteed from surface to ultrasonic depth

13. 6. Reference
Roux, A., et al. Tensile response of the muscle-tendon complex using discrete element model. Computer Methods in Biomechanics and Biomedical Engineering, 2014, Vol.17, No. S1,
Maria A., et al. Model for Vickers microhardness prediction applied to SnO2 and TiO2 in the normal and high pressure phases. Journal of the European Ceramic Society, 2014, Vol.34, Issue 15,
Aude P., et al, Towards a real time release approach for manufacturing tablets using NIR spectroscopy, Journal of Pharmaceutical and Biomedical Analysis, 2014, Vol. 98, 60-67
Xiangjun Chen, et al, The finite element analysis of austenite decomposition during continuous cooling in 22MnB5 steel, Modeling and Simulation in Materials Science and Engineering, 2014, Vol.22, Number 6
GRUM, Janez. A review of the influence of grinding conditions on resulting residual stresses after induction surface hardening and grinding. Journal of Materials Processing Technology, 2001, 114.3:

14. 7. Appendix 7.1 Specification of Ultrasonic tester
At last comparing real, ultrasonic measured, and hardened depth.

15. 2. Plan
Q & A