Decrease of sintering temperature of high speed steel powders

hardness. shown

Fracture strength

to depend

size and toughness treatment, caused

in bending was

on the ceramic

particle

SUPERDUCTILITY HIGH SPEED

IN PM PROCESSED

a decline

and

in

fracture toughness hardness.

bend

tempering strength

without

heat I. Shytka, K. Gogayev (Inst. for Problems

and

any increase

in

Materials

Science,

CONSOLIDATION

AND

Kiev, Ilkraine).

NANOCOMPOSITES

rate sensitivity

BY HIP

strain rate. Elongation at

P. Matteazzi

ct

al

(Ilniversity

of

increases

lidine,

11OO’C

ductility

and

Strain

with decrease

in

of 630X was found sec.

The

fabrication

milled

compacts

powder

from

by

Fe,&

Fe

and

hardness

of

Fe-(66

from

high

C;YP and

formed of

HIP

by increased

porosity.

powder.

651)

to

AND SINTERING COMPOSITE

was

SINTERED MADE

Vicker’s

1000

and

of

4 to

PRODUCED

The

Research,

pressing

of steel

OF METAL

H.

sintering

and

behaviour

25volXCr,,C,1 compared

was with

between

density and

condit.ions

were

reported.

of the

materials

were

tested

service

conditions.

(Mitsubishi

Some under

speed

Materials

from

powder

forged

and

water

rupture

compared

conventional

atomized

to eliminate

a transverse

PHASE

2

GPa

of

for

IN OXIDE ALLOYS

Energy Commision,

OP.

Problems

N.M. Mordovets

in Materials

Kiev, [Jk-

The

phase

and

composition of two

high

from Ar atomized

speed

and water cooled

were investigated

as functions

and powder to increase

had

TITANIUM

resistance

was brittle. The brittleness to the formation processing.

of

but

SPEED

particle

of

during

size.

and

to

increase

OF T42 HIGH

REINFORCED

AND NIOBIUM

K. P&hang, U. Birth (University nology, Dresden, Germany).

was

of the

sintering

of Tech-

of T42

high

steel with up to lOvol’%TiC or NbC described.

incorporated

The

into

the

carbides steel

powders

by

during

rcbported

be attained

that

for

Technical

high

density

in T42 high speed

steel

with addition of up to 6% VC or NbC by sintcring in N-H-CH, at 1160 C. N was absorbed t)y the steel forming a carbonitridr which inhibited austenite grain growth. Potential cost savings, Iow(br sintering

t.emperature.

were identified and improvements structure and properties described.

in

addition

sintering

and was counteracted

by

of P or B.

Dispersion materials

OF HEAT TREATMENT

Bhadeshia

et

Cambridge,

oxide

ON IN

al

(University

of

IJK),

dispersion

MA6000

alloys

carbides

dissolve.

Al-Zr

phases

were

unrelated

strengthened

described.

Mz:jC6i

The Ti rich, Y-AI, and Y-

are

heating.

more

stable

but

grow

This was considered

to be

to rectystallization.

STRUCTURE AND PROPERTIES OF SINTERED DISPERSION HARDENED COPPER-TITANIUM

ALLOYS

G. Petzow et al ( Max-Planck

Inst., Stut,tgart,

It was reported that a (:u-Ti been prepared, from elemental TIN and

alloy had powders

<‘. by mechanical

alloying.

behavinur was influenced

was reported

to be 350.

Stainless steels LOW CYCLE FATIGUE BEHAVIOUR OF A PM AUSTENITIC STAINLESS STEEL B. Karlsson

OF IRON OXIDE ALLOYS

D.M. Jaeger, A.K. .Jones (AEA Technology, Risley. Cheshire, UK). It was noted oxide dispersion

that mechanically alloyed strengthened alloys have

(Chalmers

Uni-

versity of Terhnology. Giiteborg, Sweden) The low cycle fatigue properties of a fully dense PM austenitic

STRENGTHENED

by a

size of

100 nm. Tensile strength at rnom temperature was above 1000 MPa with 15’% elongation and the Vickers hardness

II. Lindstedt,

strengthened

MICROSTRUCTURE DISPERSION

of

from

were

J.J. IJrcola

San Sebastien,

dislocations

PRECIPITATES AND DISPERSOIDS NICKEL SUPERALLOY

Precipitation

TEMPERATURE OF HIGH SPEED STEEL POWDERS (Centre

EFFECT

with

BY

CARBIDES

mechanical alloying and it was shown that the steel powder particles had a layer of dispersoid particles. This impeded diffusion

c>t al

light

grain size of 500 nm and a dispersoid

speed

OF SINTERING

and Investigations,

of

Creep

in the

Germany).

STEEL

A study

nigh speed steels

analysed

the proportion

was attributed Cr,O:$

of oxide

steels

Lyngby, Denmark)

wear

was

presence

pin dislocations.

dispersoids.

during

BEHAVIOUR

Uni-

for

raine)

SINTERING

(Technical

(Inst.

Science,

the

which

behaviour

alloyed

Rachek,

to

of two MA ODS Fe High creep resistance

Changes in precipitates and dispersnids during heat treatment of mechanically

STEEL

It was reported that, a Co base alloy with a fine dispersion of Al,O,l particles

the

was

to depend

STRENGHTENED

attributed

H.K.D.H.

AND

austenitc

due to

stages

a

OF HIGH SPEED

of retained hardness.

0. Kraemer

anhanced

12 pm porosity

high speed steel.

COMPOSITION

MICROHARDNESS

B was reported

versity of Denmark,

size low

strength

with

sintered

alloy composition

OF A COMPOSITE

N. Caspersen.

Corp,

that a fine grain sintcred at a

steel

temperature

powders

DURING

SUPERALLOY

could

A

all

product

ALLOYED

detachment

It was reported

microhardness

OF OXIDE

PROCESSING

Spain ) It was

DISPERSION

was

Saitama, Japan).

made FORMATION

Studies

MECHANISMS

MECHANICALLY

Cambridge,

unreinforced steel. Pressing was at up to 1000 MPa and sintering at 1120 to 1350’ C

DECREASE

finished

Creep properties alloys were described.

BY WATER ATOMIZATION

Kohno

had

Inst of Production

with

in N/H. Relationships

STEELS

FINE POWDERS

Lulea, Sweden).

and

powders

investigated

process

CREEP

dispersoids

high

WEAR PARTS

(Swedish

HIGH SPEED

FROM

4.5 GPa -J-O. Lundqvist Engineering

to

at

given. The structure was shown on oxide distribution.

C. Zakine et al (Atomic

milling

indentation fracture toughness 9 MPa.m’ ” were reported.

MATRIX

to energy

during

graphite

levels

PRESSING

evaluation

powder

for

Saclay, France),

94)vol’bFe:,C described.

microstructural

suitable

applications.

high

[Jdine, Italy). The

and oxidation

makes them

Superductility

10m4 per

is reduced

strength

which

exchanger

from

was found in fine grained materials.

OF IRON-IRON

in

The ductility of sintered high speed steel at 900 to 1150 C and strain rates of lo-4 to 10 ’ per set was investigated.

MECHANOSYNTHESIS

temperature

resistance

of the steel matrix. Heat

hardening

CARBIDE

high

STEEL

stainless steel, made by

HIP, and a cast. wrought steel, wcrc compared. The cast ‘wrought steel was shown to have superior resistance to fatigue failure. Nucleation and growth of surface cracks were investigated. Crack initiation was found at oxide particles in the sintered specimens. (&vised abstract from MPR. April

1995. page 42).

MPR

June 1995

39