TY - GEN
T1 - Sintering and heat-treatment of injection moulded 440K-type martensitic stainless steel compacts
AU - Yousaf Anwar, M.
AU - Bhero, Shepherd
AU - Messer, P. F.
AU - Davies, H. A.
PY - 2008
Y1 - 2008
N2 - Sintering and heat treatment of injection moulded hardenable stainless steel powder (440Ktype) compacts has been studied. The binder system, known as the Sheffield Binder System, was used, which is comprised of two polymers, a major component of water soluble polyethylene glycols (PEGs) and a minor component of very finely dispersed polymethyl methacrylate (PMMA) derived from an emulsion. Mixing of a number of different feedstocks was carried out manually. Following the identification of the optimum binder composition (20 wt. % PMMA, 80 wt. % PEGs) and solid loading (68 Vol. %), several test specimens were injection moulded for further processing. The PEGs were removed by leaching with water. The PMMA was removed by pyrolysis, prior to the sintering stage. Samples were sintered to ~ 99% of theoretical density. With careful control of the various processing parameters, including sintering temperature and time, cooling rate and heat treatment conditions, good mechanical properties including high hardness of HRC 60 were attained. In an attempt to reduce the process cycle time, the sintering ramp was modified to include solutionising and oil-quenching in a single sintering cycle. The hardened samples were tempered at temperatures from 150 to 350 °C for 2 hours. Scanning electron microscopy was used to reveal the micro-structural changes during various sintering and heat-treatment stages.
AB - Sintering and heat treatment of injection moulded hardenable stainless steel powder (440Ktype) compacts has been studied. The binder system, known as the Sheffield Binder System, was used, which is comprised of two polymers, a major component of water soluble polyethylene glycols (PEGs) and a minor component of very finely dispersed polymethyl methacrylate (PMMA) derived from an emulsion. Mixing of a number of different feedstocks was carried out manually. Following the identification of the optimum binder composition (20 wt. % PMMA, 80 wt. % PEGs) and solid loading (68 Vol. %), several test specimens were injection moulded for further processing. The PEGs were removed by leaching with water. The PMMA was removed by pyrolysis, prior to the sintering stage. Samples were sintered to ~ 99% of theoretical density. With careful control of the various processing parameters, including sintering temperature and time, cooling rate and heat treatment conditions, good mechanical properties including high hardness of HRC 60 were attained. In an attempt to reduce the process cycle time, the sintering ramp was modified to include solutionising and oil-quenching in a single sintering cycle. The hardened samples were tempered at temperatures from 150 to 350 °C for 2 hours. Scanning electron microscopy was used to reveal the micro-structural changes during various sintering and heat-treatment stages.
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M3 - Conference contribution
AN - SCOPUS:84902215007
SN - 9781899072033
T3 - Proceedings of the Euro International Powder Metallurgy Congress and Exhibition, Euro PM 2008
SP - 215
EP - 220
BT - Proceedings of the Euro International Powder Metallurgy Congress and Exhibition, Euro PM 2008
PB - European Powder Metallurgy Association (EPMA)
T2 - European International Powder Metallurgy Congress and Exhibition, Euro PM 2008
Y2 - 29 September 2008 through 1 October 2008
ER -