Effect of compaction pressure and powder grade on steam-oxidised sintered iron

Copper

Fatigue crack growth in rotary forged sintered PM low-alloy steels

Dispersion-strengthened copperalumina made by high-energy milling V.M.Rajkmc, M.V.Mitkiu. (‘Vinca Materials Science Laboratory, Belgrade, Yugoslauia.) Inr. J. Powder Metall., Vol36, No 8, 2000, 45-49. Cu-( 1, 2.5 and 3S)wt%Al

Prealloyed

powders were high-energy hardening

alloy

milled to evaluate

due to in situ internal

oxidation

of

Al to Al,O,.

Surface oxides were removed by

H reduction.

Powders were hot pressed in Ar at

800°C for three hours at 35MPa. ness was measured 3.5%Al(

203)and

Micro-hard-

and was greatest

in Cu-

was a factor of three to four

times greater than electrolytic

et al. (Uniuersiy of Benin, Benin,

Nigetia.) Powder Metall., Vol44, No 1, 2001, 62-66.

Powder and process parameters, in production of Cu-graphite

oxides

S.Peamck, J.R.Moon. (University of Nottingham, Nottingham, UK.) Powder Metall., Vol43, No 4, 2000, 345-349. Fatigue crack propagation, was investigated

in plane strain,

for three low-alloy

PM steels,

processed to high density by rotary consolidation, sintering

and heat treatment.

were between

those for pressed and sintered

steels

and powder

stress intensity

forged

Properties

alloys.

Threshold

was similar but resistance

to

fatigue crack growth was lower in comparison with wrought steels. Reasons for this were discussed in terms of microstructures.

tion and properties

of the compacts.

shown that spherical

It was

powders give materials

Increased use of austenitic stainless steel, due to improvements

in corrosion

poor tribological

properties,

resistance,

but

are noted.

It is

with lower friction and higher electrical resistiv-

reported that 3 16L stainless steel-sic

ity than powders with flake-like or acicular mor-

made in an effort to improve performance.

It is

shown that there is reaction

and

phologies.

Results

were presented

for binary

materials and alloys with up to 2.5wt% Pb or Zn.

between Sic

phase at 400°C.

there was complete

Iron and steel

had been

matrix during processing forming a low melting point Fe-Sic

Above

400°C

melting of the composite.

C.S.Wright et al. (University of Bradford, Bradford, UK.) Powder Met&, Vol43, No 3, 2000, 270-274.

A.S.Wronski et al. (University of Bradford, Bradford, UK.) Powder Metail., Vol43, No 4, 2000, 353-358.

pressed and sintered ties determined

and mechanical

as functions

proper-

of process condi-

tions. Density decreased with increase and sintering

temperature.

Tensile

and transverse rupture increased and increased sintering

were

in %C strength

up to O.B%C

temperature

and cool-

ing rates. Elongation

decreased with increased

%C but was higher

at higher

perature.

Mechanical

improved by heat treatment. to O.B)%C is considered

sintering

properties

temwere

Effects of 0.5%Mo and properties

on processing,

structure steel,

materials

were investigated

by with

regard to heating and gas flow rates and moisture, dew point, in the sintering atmosphere, or N-25vol%H.

Densities

rate.

Mechanical

Impact forging of sintered preforms

steel

A.A.He&ckson et al. (Good Harbor Assoc., Inc., L&id, USA.) PowderMetall., Vol 43, No 4, 2000, 327-344. Studies of forging hammers to impact forging

properties

are

J.D.B.de Mello et al. (Federal University of Uberi&&, Uberf&dia, Brazil.) Powder Metall., Vol 44, No 1, 2001, 53-61. Steam

oxidation

of steel is discussed with

regard to the effects of the oxide films produced on

mechanical

and

tribological

properties.

pressure and powder size

on structures, oxide content,

hard-

is shown that impact forged powder materials

ness and surface topography

can attain levels of mechanical

properties com-

sintered

wrought

pressed from four size ranges at 300MPa

www.metal-powder.net

of the

thrust

Flank wear is

to thrust force. The

force/material

rion of machinability

removed

than mean thrust force.

the MnS

is beneficial.

Drilling

of

sinter hardening

steels was examined.

Drilling

in a pre-sintered

state was preferable

to green

Titanium Densification of titanium alloy powder compacts at high temperature S.T.Hong et al. (Pohang University of Science and Technology, POhmg, Korea.) Powder Metall., Vol 44, No 1, 2001) 34.40. Hot pressing

of Ti-6%Al-4%V

powder was

investigated. Yield function and a strain-hardening factor were incorporated

in a finite element

and calculated data are

Densification of titanium alloy powder during hot isostatic pressing K.T.Kim, H.C.Yang. (Pohang University of Science and Techno&, POhmg, Korea.) Powder Metall., Vol 44, No 1, 2001, 41-47. HIP

densification

investigated pressures. finite

The

element

parison

of Ti-6%Al-4%V

was

under a range of temperatures Abouaf

and

model was used in a

analysis programme

is made

between

and com-

calculated

observed data for densification,

Tungsten

Effects of compaction

equipment

steels in drilling

curve is suggested to be a more accurate crite-

Effect of compaction pressure and powder grade on steam-oxidised sintered iron

distribution

material and process parameters. It

high-strength

slope

and density distribution.

equipment,

with

shown to be proportional

described.

of steel preforms are reviewed with reference to

“State-of-the-art”

of sintered

and

shape change

Fe-1.5%Mo-(0.5

to be a useful range of

composition.

parable

H

up to 7.1gm.cmd3

were attained. Sintered structures depended on cooling

Machinability

and tool wear was investigated.

deformed geometry and density distribution.

of PM 3S%Mn-0.7%C

made from a range of starting pressing and sintering

of

compared for values of density/applied pressure,

Sintering structure mechanical properties of PM manganese molybdenum steels

and 0.5 to 1.2)%C

and

C.Blais et al. (Don&r Metal Powders Ltd., Quebec, Canada.) Powder Metall., Vol44, No 1, 2001, 67-76.

program. Experimental

Effects of composition process condition density on properties of iron-molybdenum

Fe-1.5wt%Mo-(0

Fez03

machining.

S.N.Patankar, M.J.Tan. (Nanyang TechnoloGcal Unwersity, Singapore.) Powder Metall., Vol 43, No 4, 2000, 350-352.

with reference to fric-

to comprise

Characterisation of machinability sintered steels during drilling

prealloying

Role of reinforcement in sintering of stainless steel-silicon carbide composite

compacts for industrial applica-

tions, were investigated

are shown

Fe,O,.

Effect of MnS was studied. It is considered that

Cu.

Sintered copper-graphite powder compacts for industrial applications F.F.O.Owmwense

and steam treated at 540°C for two hours. The

is discussed.

steels.

600MPa,

Fe were investigated. sintered

at 112O’C

of steam treated Samples

were to

for 30 minutes

Effects of nickel on properties of tungsten-silver electrical contact materials B.&kal et al. (Istmnbul Technical University, Istambul, Turkey.) Powder Metall., Vol44, No 1, 2001, 77-81. W-35wt%Ag

and W-35%Ag-Ni

were mechanically

furnace cooled and re-sintered. tron microscopy butions

powders

alloyed, pressed, sintered, Scanning

revealed homogeneous

elecdistri-

of W and Ag in milled powders and

compacts. Ni is shown to increase hardness and reduce erosion of contacts.

Addition

of l%Ni

increased service life by 10 times.

MPR

July/August

2002

85