- Email: [email protected]
Physical chemistry of sintering of stainless steels
Stainless
steels
and high alloy
CORROSION OF HIGH DENSITY SINTERED STAINLESS STEEL WITH PHOSPHIDE SINTERING AID
J.Bolton, H.Preusse. (University of Bradford, Bradford, Yorkshire, UK.) Addition of Cu,P to 316L stainless steel was reported to enhance sintering above 1050°C by promotion of a liquid phase. Optimum processing gave densities in excess of 98% with less than 2% interconnected porosity with addition of 8 to 10% Cusp when sintered at 1200 to 1250°C. Without Cusp only 80% density was attained with 17% interconnected porosity. The increased density resulted in improved corrosion resistance. CORROSION CREEP AND STRENGTH OF STAINLESS STEEL FOR AUTOMOTIVE EXHAUSTS A.E.Segall et al. (Pennsylvania State University, USA.) The need for a database of properties of PM stainless steels was noted and it was reported that work had been carried out to establish one for austenitic and ferritic materials. Parameters required
for design include strength, creep, fatigue and corrosion properties. Results from the database development were compared with values currently used for cast/wrought materials. PM stainless was considered to be of value in automotive applications. INFLUENCE OF SINTERING ATMOSPHERE ON STRUCTURE PROPERTIES OF SINTERED STAINLESS STEEL
The effects of additions of Cu, compacting pressure and powder granulation, on corrosion properties of a stainless steel containing B, were investigated in aqueous solutions, by a range of electrochemical techniques and by weight loss. The presence of Cu was reported to be beneficial in comparison with steel without Cu.
AND PHYSICAL CHEMISTRY OF SINTERING OF STAINLESS STEELS
J.M.Ruiz Roman et al. (Polytechnic University of Madrid, Madrid, Spain.) A problem arising in the sintering of stainless steels, the formation of different microstructural constituents, was identified. A study of the effects of sintering atmosphere on the structures of a range of single phase and duplex stainless steels was described. Dissociated NH,, N-H mixtures and vacuum were used. Structures obtained were related to the mechanical properties. CORROSION RESISTANCE OF A SINTERED AUSTENITIC STAINLESS STEEL VCandea et al. (Technical University of Cluj-Napoca, Cluj-Napoca, Romania.)
P.Bracconi et al. (University of Burgundy, Dijon, France.) Surface reactions and their role in steel were stainless sintering reviewed with respect to thermodynamics and surface conditions of atomized powders and solid/gas interactions. Emphasis was on 304L and 316L steels. It was shown that the stable oxide films formed during atomization can be reduced during sintering. The importance of mass transfer inside pores to ensure complete reduction throughout the compact was emphasized. The effect of residual oxide was considered for nonreducible oxides, such as Al,O,, partially reducible oxides and those totally reduced by added C.
NEW OSTERWALDER PRESS TECHNOLOGY MechanicalHydraulic Powder Compacting Press KPP from 630-3800kN 0 Upper ram mechanically driven for low energy consumption l Iron Powder l Die and additional
axes hydraulically driven
l 12 Stroke 1 min l Press KPP 2500
0 Requiered tolerance of weight 258,50 g - 26150
g
a Tolerance within 0,Ol mm a Highest productivity for complex structural parts
I I
42 MPR September 1999
OSTERWALDER AG tndustriering 4 Postfach 176 CH-3250 Lyss/Switzeriand Phone +41 32 384 26 56 Fax +41 32 384 45 72
OSTERWALDER, INC 10835 Millington Court PO. Box 42536 Cincinnati, Ohio 45242 Phone513 / 936 9006 Fax 513/9369008 Internet: http://www.osk zrwalder.com
OSTERWALDER
E-Mail: [email protected]
l
steels
and high alloy
CORROSION OF HIGH DENSITY SINTERED STAINLESS STEEL WITH PHOSPHIDE SINTERING AID
J.Bolton, H.Preusse. (University of Bradford, Bradford, Yorkshire, UK.) Addition of Cu,P to 316L stainless steel was reported to enhance sintering above 1050°C by promotion of a liquid phase. Optimum processing gave densities in excess of 98% with less than 2% interconnected porosity with addition of 8 to 10% Cusp when sintered at 1200 to 1250°C. Without Cusp only 80% density was attained with 17% interconnected porosity. The increased density resulted in improved corrosion resistance. CORROSION CREEP AND STRENGTH OF STAINLESS STEEL FOR AUTOMOTIVE EXHAUSTS A.E.Segall et al. (Pennsylvania State University, USA.) The need for a database of properties of PM stainless steels was noted and it was reported that work had been carried out to establish one for austenitic and ferritic materials. Parameters required
for design include strength, creep, fatigue and corrosion properties. Results from the database development were compared with values currently used for cast/wrought materials. PM stainless was considered to be of value in automotive applications. INFLUENCE OF SINTERING ATMOSPHERE ON STRUCTURE PROPERTIES OF SINTERED STAINLESS STEEL
The effects of additions of Cu, compacting pressure and powder granulation, on corrosion properties of a stainless steel containing B, were investigated in aqueous solutions, by a range of electrochemical techniques and by weight loss. The presence of Cu was reported to be beneficial in comparison with steel without Cu.
AND PHYSICAL CHEMISTRY OF SINTERING OF STAINLESS STEELS
J.M.Ruiz Roman et al. (Polytechnic University of Madrid, Madrid, Spain.) A problem arising in the sintering of stainless steels, the formation of different microstructural constituents, was identified. A study of the effects of sintering atmosphere on the structures of a range of single phase and duplex stainless steels was described. Dissociated NH,, N-H mixtures and vacuum were used. Structures obtained were related to the mechanical properties. CORROSION RESISTANCE OF A SINTERED AUSTENITIC STAINLESS STEEL VCandea et al. (Technical University of Cluj-Napoca, Cluj-Napoca, Romania.)
P.Bracconi et al. (University of Burgundy, Dijon, France.) Surface reactions and their role in steel were stainless sintering reviewed with respect to thermodynamics and surface conditions of atomized powders and solid/gas interactions. Emphasis was on 304L and 316L steels. It was shown that the stable oxide films formed during atomization can be reduced during sintering. The importance of mass transfer inside pores to ensure complete reduction throughout the compact was emphasized. The effect of residual oxide was considered for nonreducible oxides, such as Al,O,, partially reducible oxides and those totally reduced by added C.
NEW OSTERWALDER PRESS TECHNOLOGY MechanicalHydraulic Powder Compacting Press KPP from 630-3800kN 0 Upper ram mechanically driven for low energy consumption l Iron Powder l Die and additional
axes hydraulically driven
l 12 Stroke 1 min l Press KPP 2500
0 Requiered tolerance of weight 258,50 g - 26150
g
a Tolerance within 0,Ol mm a Highest productivity for complex structural parts
I I
42 MPR September 1999
OSTERWALDER AG tndustriering 4 Postfach 176 CH-3250 Lyss/Switzeriand Phone +41 32 384 26 56 Fax +41 32 384 45 72
OSTERWALDER, INC 10835 Millington Court PO. Box 42536 Cincinnati, Ohio 45242 Phone513 / 936 9006 Fax 513/9369008 Internet: http://www.osk zrwalder.com
OSTERWALDER
E-Mail: [email protected]
l