1. business and industrial
2. chemicals industry
3. plastics and polymers

Lectured by: Prof. VIRGIL GEAMAN
Transilvania University of Brasov, Romania
IISS’15 KARABUK – TURKEY (01-03 April 2015).
Departments:
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Materials and Welding Engineering
Materials Science
Bachelor’s
degree programmes – full-time education
Industrial Engineering field: Welding Engineering ; Industrial Safety Engineering
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Materials Engineering field: Materials Science; Computer Science in Materials
Engineering
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Engineering and Management field: Economic Engineering in Mechanics
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Master’s
degree programmes – full time education
Industrial Engineering field: Welding Engineering of Advanced Materials
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Materials Engineering field: Engineering and Management of Advanced Metallic,
Ceramic and Composite Materials
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Ph.D.
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programmes
Industrial Engineering field:
Materials Engineering field:
supervisors
supervisors
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Technology;
Equipment used;
Applications:
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Powder consolidation
Healing of casting defects
Diffusion bonding
Food processing
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Hot Isostatic Processing (HIP)
◦ Application of high temperature and high pressure
to remove internal porosity, consolidate powder for
alloys, and diffuse bond.
◦ Materials that can be HIPped:
 Titanium, beryllium, steel, aluminum, superalloys;
 Castings, ceramics, etc.
 Food processing.
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Alloys are sometimes created using
Powder Metallurgy
Alloys have trouble becoming
chemically homogeneous
When they are allowed to form on their
own they form large grains that do not
mix as shown at right
Using HIP it is possible to construct an
alloy that has good chemical
homogeneity and refined
microstructures
Small grain size, compared to previous
slide, can be seen at right
Leads to improved mechanical
properties
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Turbine blades
Need for a blade that has cooling channels
to encounter high temperatures
Using HIP it is possible to form a
component from multiple components that
are diffusion bonded
Can maintain low weight while being able to
withstand high temperatures and stresses
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Components can be joined through
Hot Isostatic Processing using
Diffusion Bonding
Two materials undergo no more than
a few percent macroscopic
deformation
Important because welding and
fastening produce larger
deformation which leads to stress
points and weakening of material
Surfaces of materials to be joined
bond’s collapse and join with each
other.
The material is then bonded with a
100% perfect bond
Barely detectible interface of
diffusion bonded material seen at
right
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Pressure vessel contains entire
process
Furnace enclosed in vessel
Pressure vessel insulated from
furnace
Allows combination of high
temperature and high pressure
Pressures reach 200 MPa
Temperatures reach 2000
degrees Celsius
Size of pressure vessel ranges
from smaller than 4”X12” up to
46”X80”
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HIP EQUIPMENT
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The aluminum alloys are offering the highest degree of
hardness by heat treating. The development of the
range of these alloys is determined by the fact that
alloying is enlarging the possibilities of precipitation
hardening.
The particularities of the final heat treatment made to
pieces from duralumin alloys – obtained through plastic
deformation – especially through forging or extrusion,
are determined by the characteristics of the plastic
deformation structure.
The paper presents the influence of the heat treatment
applied to pieces made from duralumin alloys, before
and after isostatic compaction. There are presented
experimental results, conclusions of these experiments
and are given some proposals for new technologies with
positive effects over the specific industry.
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Casting defects such as internal pores
causes weakness in materials
Dark spaces at right are internal pores
Voids act as stress risers
Leads to inaccuracy when predicting
yield and ultimate strengths, scatter
With HIPping it is possible to change
the material to a plastic state, collapse
the voids, and bond the voided
surfaces together (right)
The result is a stronger material that
has less scatter with ultimate and yield
strengths.
Accomplished though creep
mechanisms and/or compressive
plastic deformation
Lot
No.
Tensile strength
[N/mm2]
Compression strength
[N/mm2]
Elongation
[%]
Classic test
CIP test
Classic test
CIP test
Classic test
CIP test
1
131.2
148.0
297.8
336.2
8.92
16.65
2
129.2
142.2
292.6
331.7
7.74
16.90
3
120.4
139.2
287.1
328.2
8.16
16.07
4
118.4
135.0
287.6
335.3
7.16
15.90
5
119.8
137.3
288.7
334.6
7.86
15.82
Lot
No.
Compacting
time
[min]
1
0
2
5
3
10
Lot
No.
1
2
3
4
5
6
7
8
9
10
Initial
porosity
[%]
Compacting
time
1.723
[min]
1.723
0
5
1.723
10
15
20
1.723
25
30
1.723
35
40
1.723
45
Porosity after
applying classical heat
treatment
[%]
Initial
porosity
[%]
1.723
1.723
1.723
1.723
1.723
1.723
1.723
1.723
1.723
1.723
Porosity after
applying classical heat
treatment
1.723
[%]
1.688
1.723
1.688
1.612
1.612
1.544
1.502
1.544
1.454
1.376
1.502
1.123
0.876
1.454
0.542
Porosity after classical heat
treatment with
CIP applied in the incubation
period [%]
Porosity after classical heat
treatment with
CIP applied in the incubation
1.723
period [%]
1.723
1.671
1.531
1.452
1.324
1.131
1.022
0.007
0.000
0.000
1.671
1.531
4
15
1.452
5
20
6
25
7
30
1.723
1.376
1.022
8
35
1.723
1.123
0.007
9
40
1.723
0.876
0.000
10
45
1.723
0.542
0.000
1.324
1.131
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From this analysis it clearly results that the porosity is quickly eliminated,
respectively at the same time of compaction the number of pores is
decreasing with approx. 20-25%.
All mechanical properties are increasing with a medium value of 16.54
N/mm2 for Tensile strength, with 42.44 N/mm2 for Compression strength
and with 8.30% for Elongation.
The hardened alloy is becoming mild and formable (as after solid-solution
quenching), if it is reheated a short period 0.5-2 minutes, at the temperature
of 250oC, process called reversion. It is also useful from technological point
of view, as high formability from the incubation period after quenching.
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According to these aspects, the authors are proposing a new technological way of compaction
by using cold isostatic pressing process, for the given duralumin alloy, with the following
parameters:
◦ P = 120 MPa; T = 20 oC; t = 40 min.
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The old technology used by applying CIP at the final treatment supposed:
◦ P = 150 MPa; T = 20 oC; t = 60 min.
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The new variant proposed gives us the following advantages:
the working pressure can be reduced substantially;
the time of exposure can be also reduced in comparison with the classical technology.
Although this decreasing in time is major in the case of an industrial production, it has an
essential role concerning the productivity and with the decreasing of working pressure, all the
components of the high pressure equipment are protected, which leads to the growing of
working life and security in exploitation.
By analyzing the experimental results, it can be concluded:
- after fast cooling, the hardness decreases in all cases - comparing to the hardness after plastic
deformation;
- after ageing, the hardness of the samples is increasing, but not so high as after applying CIP
treatment in the incubation period.
The fact gives us the right to say that after plastic deformation, it must be applied the final heat
treatment for the pieces that need higher hardness under working conditions - and we
especially recommend this type of treatment - with applying CIP treatment after solid solution
quenching - in the incubation period.
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HPP is the application of hydrostatic compression in the range
of (100-1000) MPa that is capable of inactivating
microorganisms. In the early 1990s, Japan and other nations
introduced the use of HPP of food to inactivate barosensitive
microorganisms. An advantage of HPP is the minimal effect it
has on covalent bonds; thus, minimal damage occurs to
flavors, aromas, provitamins, and vitamins. A brief review of
high-pressure biotechnology in medicine and pharmaceutical
sciences discusses some effects of HPP action on biological
substances. HPP has been successfully applied to RTE meats,
seafood, marinated raw meats, and some processed fruit and
vegetable products.
However, HPP caused product damage to watermelon, raw
apple slices, and bread.
In Figure 1 is presented an HPP unit for food processing,
designated for preparing packaging food with discontinuous
movement.
Microorganism type
Comments
Food
Sausages
Enterobacteriaceae and
Listeria
500 MPa for 5 min = 80°C for 40 min.
Milk
L. monocytogenes,
Salmonella, and E. coli
O157:H7
Required multiple passes for pressures <300 MPa. at
46-60°C, prior to Dynamic High Pressure (DHP) enhanced killing.
DHP less effective than HPP.
Best if total bacterial load <105.
Juices and organic
acid
liquids
S. aureus, Bacillus spp.,
L. moncytogenes, E. coli
O157:H7, Salmonella
Enteritidis, S.
Typhimurium, yeast
8-log10 reduction at 345 MPa at 50°C - 5 min. except for S. aureus.
Most vegetative cells are sensitive to 700 MPa, but not spores.
8-log10 reduction in yeast at 304 MPa at 25°C, pH 4.0 for 10 min.
Generally, Gram-negative bacteria are more sensitive to HPP.
Yogurt, jams,
jellies, juices,
tomato sauces, and
other acidic
products,
fish, sliced meats
Multiple pathogens
Use where spores are not an issue as they cannot grow out at low pH.
Variable pressure sensitivities with various
commodities.
Exponential phase is more sensitive than stationary phase.
Strain to strain variability is greater for HPP than other processes.
Net volume decrease, proteins may enature, gelation may occur, lipid phase
changes may occur, increased ionization of dissociation.
Eggs
E. coli
Accumulation of injured cells at pressures less than 400 MPa.
Biphasic inactivation of E. coli at 5°C vs. linear exponential at 25°C.
Vegetables and
general
Small size and cocci
Mechanisms of pressure resistance.
Small size and cocci shape are generally more resistant to HPP.
Specific porins increase resistance.
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HIP enables to adjust fine, isotropic microstructures in duplex stainless steels,
which is fundamental to attain high strength - high toughness combinations.
Valve bodies and manifolds for oilfield uses can be produced by hot isostatic
pressing of duplex stainless steel powders.
Hot isostatic pressing enables to produce bi-metallic compounds by powderpowder or by powder-solid body bonding. The method is successfully applied for
cladding of more ore less complex shaped parts like valves.
Hot isostatic pressing enables to produce hollow structures by HIPing of a
pipe or tube system with a metal powder. The realization of internal cooling
passages is a typical example.
Hot Isostatic Pressing has long been an essential process in the production of
high-performance cast and PM parts for critical applications. Thanks to the recent
development of higher capacities, shorter cycles, and precise control systems, HIP
today is significantly more cost-effective, and will be even more so in the future. As
a result, this proven technique is becoming economically justifiable to a growing
number of manufacturers, and innovative new applications are continually being
tested and adopted.
There are a lot of phenomena that occur to make a good practice for
industrial application in the field of HIPing consolidation for metallic or ceramic
materials. But these phenomena are very difficult to be controlled. In the last years a
lot of scientist are trying to give more details in this field to help the designers to
have more complete data bases for practice use.
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[1]. Boeckeler, B.C. -“Development of Keziz Process”, Keziz Seminar, Kennametal, Inc., Latrobe, PA, September (1971).
[2]. Hebeison, J.C. - “HIP Technology – The State of the Art After 50 Years”, HIP International Conference, Paris, France, May
22-25, (2005).
[3]. Mashl, S.J. - “The Metallurgy of Hot Isostatic Pressing”, HIP Seminar, Grand Rapids, MI, October 24-25, (2001).
[4]. Hebeison, J.C. - “HIP from Aerospace to Automotive”, HIP Seminar, Grand Rapids, MI, October 24-25, (2001).
[5]. Zimmerman, F.X. Toops, J. - Hot Isostatic Pressing: Today and Tomorrow, Avure Technologies, Inc. www.avure.com
[6]. Semlitsch M. & Dawihl D. - Basic requirements of alumina ceramic in artificial hip joints balls in articulation with
polyethylene cups. Technicals principles, design and safety of joint implants. Hogrefe & Huber Publ, Seattle, pp. 99-101
(1994).
[7]. Lerouge S. & Sedel L. - Alumina ceramic in total joint replacement. HIP Surg, pp. 31-40 (1998).
[8]. Masson B, Willmann G, Von Chamier W. - Fiabilite ´du couple alumine-alumine dans la prothe`se totale de hanche.
Journe´es lyonnaises de la hanche, pp. 397-402 (1999).
[9]. Burger W. & Richter H.G. - High strength and toughness alumina matrix composites by transformation toughening and
in situ Platelet Reinforcement (ZPTA) The New Generation of Bioceramics. Bioceramics, Vol. 13 pp. 454-548 (2000).
[10]. Garino J.P. - The status and early results of modern ceramic-ceramic total HIP replacement in the United States.
Bioceramics in HIP joint replacement. 5th Symposium CeramTec Stuttgart. Ed Thieme pp. 88-91(2000).
[11]. Stewart T.D., Tipper J.L., Insley G. et al. - Wear of alumina matrix composite ceramics for HIP prostheses, ISTA-San
Francisco, California, USA pp. 24-27 (2003).
[12]. Willmann G. - Survival rate and reliability of ceramic femoral heads for THA. Material Science and Engineering, Ed. 29,
Issue 10, pp. 595-604 (1998).
[13].
Atkinson H.V. & Rickinson B.A. - Hot isostatic processing, Adam Hilger Series, Great Britain, (1991).
[14]. Geamăn V. - Theoretical and experimental researches regarding to isostatic processing of poured blanks made from
non-ferrous alloys, Ph.D. Thesis - "Transilvania" University of Braşov, (1995).
[15].
Geamăn V. - Proc. Int. Conf. Hot Isostatic Pressing, Andover – Massachusetts, U.S.A., pp. 221-223 (1996).
[16]. Ratke L. - Lectures on sintering. Institute for space simulation DLR Cologne Germany, (1993).
[17].
Froes F.H. - Fourth International Conference on Isostatic Pressing, Journal of Materials, U.S.A. MA. (1991).
[18].
James P.J. - Isostatic Pressing Technology, in Metals and Materials, Nr. 10, pp. 541- 546 (1992).
THANK YOU FOR YOUR
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