Hot Isostatic Pressing Technology for Indian Test Blanket Module Fabrication

Defence Metallurgical Research Laboratory Kanchanbagh PO, Hyderabad-500058, India.

Email: gouduapparao@rediffmail.com

Dr. G. Appa Rao

22 July 2008.

Introduction

Selection of appropriate materials and fabrication technologies for various components for fusion reactors relies on trade-off between multiple requirements which are mainly driven by:

Economic Safety and Environmental effects

Materials:

Martensitic steels Non-Ferrous alloys Ceramics Vanadium alloys SiC/SiC Composites Ti and Cr alloys

Fabrication Technologies:

Cutting and machining Special welding techniques Investment casting Hot isostatic pressing (HIP)

Significance of HIP Technology

Implementation and joining of F/M steels are an important goal due to the complex geometry of the blanket modules.

Necessity for reducing the leak level and maintenance.

Advanced techniques based on solid or powder HIP are to be established

Principles of Isostatic Pressing

Pascal’s Law

Warm Isostatic Pressing(WIP) 1960

Hot Isostatic Pressing(HIP) 1955

Cold Isostatic Pressing(CIP) 1913

Isostatic Pressing

Temp. RT. ~300 ºC 2000 ºC

Pressuremedium

Water +oil Water +oilInert gas

Pressure 400 MPa 200 MPa 200 MPa

Powdercontainer

Rubber RubberSteel, Ceramic & Glass

Extent ofdensification

Green compaction Full density Full density

Hot Isostatic Pressing

HIP is a an innovative thermal treatment process subjects the material / component to a combination of high pressure and elevated temperature

HIP results in near theoretical density, uniform microstructure and consistent mechanical properties

HIPing Parameters:

Temperature : 0.7 - 0.9 Tm

Pressure : 100-200 MPaTime : 2- 4 h.

Details of HIP Equipment

Densification Mechanisms of HIPing

Particle rearrangement Plasticity Power-law creep and Volume and grain boundary diffusion

Stages of HIP Densification

HIP Diagrams

Applications of HIP Technology

Cladding

Diffusion Bonding

Consolidation of Encapsulated Powder

Densification of Metal castings

Specialized Applications:

Medical Implants

HIP of ultra fine Tungsten Carbide Cobalt Hard

Metals

Rejuvenation of Deteriorated Components

Formation and Control of Pores

Joining of Fusion Reactor Components

Cost Reduction Potential for a Selected Group of Superalloy

Parts

0

25

50

75

100

AS-HIPHIP+

H .W

Conventional Processing

Cost

Red

ucti

on

Pote

nti

al,

%

CIP and HIP Facilities at DMRL

(200 Dia. X 600 HT.) mm400 MPa

(100 Dia. X 200 HT.) mm, 200 MPa1450, 2000 ºC

(270 Dia. X 990 HT.) mm, 200 MPa1450ºC

(650 Dia. X 1200 HT.) mm, 200 MPa1450ºC

HIPing of Stainless Steel Powder

40 mm

1 2

100

200

300

400

500

600

700

40 %

490

200

85 %

660

280

Str

eng

th (

MP

a), D

uct

ility

YS UTS EL.

As-HIPed Spec.

G. Appa Rao and M.Kumar, Mater.Sci. and Technol. 1997

Superalloy 718 Integral Turbine Rotor

Stainless Steel Integral Turbine Rotor

Potential of HIP for Complex Shapes

HIP Diffusion Bonding of Materials

Material forms for HIP bonding:

Powder-powder

Powder-solid

Solid -solid

Advantages:

Similar and dissimilar material can be joined

Complex shape can be joined easily

Original microstructure remains intact

ODS and FRM can be joined

Joint integrity is better than that of conventional one

Microstructure of HIP Diffusion Bonded Materials

Shaft alloyDisk alloy

Cu-Solid

Cu-Powder

SS -Solid

SS-Powder

G. Appa Rao et. al, DMRL TR2000265 (2000)

Failure did not occur at the joint

1 21

10

100

1000

RT.

25%

1128735

25%

1320776

Pro

per

ty

YS (MPa) UTS (MPa) EL (%)

DMRL Spec.

1 21

10

100

1000

650°C

20%

1030618

25%

1117750

Pro

per

ty

DMRL Spec.

Mechanical Properties of HIP Diffusion Bonded Alloys

P/M(HIP) Diffusion Bonded Hardware (DMRL)

Ni-base superalloy components

Prototype thrust chamber clouseout

Overview of Blanket Module Fabrication(Literature)

Reduced Activation Ferritic Martensitic (RAFMA) steel is the structural material for TBMs

Fabrication concepts rely on plates with internal cooling channels

Main technologies for fabrication of TBMs:

Cutting and machining of semi finished products

Joining of parts to produce the plates with internal channels

Bending of cooling plates

Heat treatment to improve the structure and properties

Configuration Details of Blanket Module

(a) Two-Step HIPing Method:

First Wall Fabrication Procedures

Involves machined grooved plates

Use of Mo- alloy massive stiffening / supporting plates between the encapsulation and the FW/CP plates

HIPing at low pressure to achieve bonding at the Interface

Removal of encapsulation and Mo plates and drilling of channels

The FW is further HIPed at high pressure to achieve full bonding

Heat treatment, testing and evaluation

(b) Single High Pressure HIPing Method / HIP forming Process:

Involves insertion of round tubes in the rectangular grooves

Ends of the tubes are welded to the plates but the tubes are not closed

During HIPing, the tubes expand and conform to the grooves

Mo- alloy supporting plates are not required

Heat treatment, testing and evaluation.

(c) Rectangular Tube (RT) Process:

Involves diffusion welding of RTs. and cover plates

HIPing to improve the joint integrity

No need for stiffening plates

There is a scope for bending the RTs. and cover plates before HIPing.

Heat treatment, testing and evaluation

FW mock up manufactured by HIP forming ( top: parts before HIP;bottom: mock up after HIP, bending and marching.

Conclusions

Fabrication of test blanket modules (TBMs) is a technologically challenging task

Hot isostatic pressing (HIP) is a promising technology for fabrication of TBMs

Considerable expertise on several aspects of HIP technology is available at DMRL to address various issues in this field

Study on development of prototype TBM components can be taken up with the existing infrastructure.

Thank you