WEAR PROPERTIES OF FE-CUC BASED MATERIALS PRODUCED BY POWDER METALURGY
In this study, Fe-Cu-C based compact in various weight ratios of iron, copper and graphite additions to starting powder have been produced by powder metallurgy. The effects of copper and graphite additions and sliding speeds during wear tests on wear behaviours were investigated. In this study, wear tests were carried out by using pin on disc sliding wear machine with the sliding speeds of 1, 1,5 and 2 msn at the constant loads of 20N. 2000 m total sliding distance was selected. Scanning Electron Microscopy (SEM) studies were carried out on the cross section of the compacts. Worn surfaces of the samples after tests were also examined by using scanning electron microscope and energy dispersive spectroscopy (EDS) analyses. The results obtained from experimental work shows that addition of copper and graphite and sliding speed effect on wear behaviours of sintered alloyed steel materials.
Microstructural and hardness chara- cterisation of sintered low alloyed steel
Purpose: The purpose of the present study is to produce low ally PM steel without any addition and with addition of ferro-boron addition by conventional PM manufacturing route at the different sintering temperature. Design/methodology/approach: Fe-Ni-Cu-Mo-C sintered steel containing 0.5 percent ferro-boron addition was used in this study. The compacts were prepared by powder metallurgy method involving powder mixing, cold pressing at 700 MPa pressure and sintering at temperatures of 1180, 1200 and 1250°C in nitrogen+% 4 H2 atmosphere for 30 minutes. The influence of sintering temperature and boron addition on the hardness and microstructure of P/M steels were investigated. Optical and scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) techniques were used for characterization of the sintered steels. Findings: The results show that increasing sintering temperature resulted in increase in hardness values; however, those values were dropped after sintering temperature higher than 1180°C. On the other hand, Boron addition contributed to hardness values at sintering temperature of 1200°C. Those values were decreased with increasing sintering temperature. Research limitations/implications: The composition of the sintered steels effect on the density values. The composition of the grain boundaries were affected from sintering temperature. Boron, carbon, molybdenum were seen in the grain boundaries of the specimen having the highest hardness values. It is thought that those compositions strongly effects on hardness values of the specimens. Originality/value: Fe-Ni-Cu-Mo-C base powder with and without boron addition low alloy sintered steel were produced. The effects composition and sintering temperature were investigated.
Traceability strategy for gear-pitch-measuring instruments: development and calibration of a multiball artifact
There is a strong demand to ensure the traceability of gear-measuring instruments (GMIs). We propose a multiball artifact (MBA) for the evaluation of pitch-measuring accuracy. The aim of the MBA is to transfer the minimum uncertainty from a calibrated value at the National Metrology Institute of Japan (NMIJ) to a measured value of GMIs at a shop floor. The MBA is composed of equally spaced high-accuracy balls around an axis. The pitch-measuring accuracy of GMIs is evaluated by measuring the angular pitch deviation of the balls instead of the angular pitch deviation of a gear. We calibrated the angular pitch deviation using a coordinate measuring instrument (CMM) at the NMIJ and adapting a multiple-orientation technique. We proposed a calibration strategy of the angular pitch deviation. The calibration value of the pitch deviation for the MBA at the NMIJ was obtained with a measurement uncertainty (U95) of 0.2 µm. We evaluated the pitch-measuring accuracy of a GMI using the calibrated MBA. Each value of U95 for the cumulative and single pitch deviations for the left and right flanks was less than or equal to 0.5 µm. The small uncertainty was transferred from the NMIJ to the GMI.