ASTM B964-25, "Standard Test Methods for Flow Rate of Metal Powders Using the Carney Funnel," was last updated on 2025-05-08 by ASTM Committee B09 and is the consensus method for timing metal powder that refuses to discharge through a Hall flowmeter funnel [S1].
Scope is deliberately narrow: B964 covers powders and powder mixtures that do not readily flow, while free-flowing grades are routed to ASTM B213 (Hall funnel). The two methods sit inside the same B09.02 base-metal powder workstream, and the Carney geometry is also used at 5 mm orifice for the parallel ASTM B417 apparent-density test [S3][S4]. For a primer on how metal powder lots are sampled, sieved and conditioned before any flow test, the wider characterisation workflow is worth mapping first.
Where B964 sits in the B09 funnel family
ASTM B213 (Hall, 2.54 mm orifice) is the first-pass flow test for nearly every lot of pressed-and-sintered metal powder. B964 is invoked only when the Hall funnel refuses to discharge, a condition typical of sub-45 µm grades, high-aspect-ratio morphologies, or binder-treated mixes that have interparticle friction too high to overcome the standard Hall head pressure [S2][S4]. B417 then uses the same Carney funnel body at 5 mm orifice to report apparent density (ADC) of the same non-free-flowing lot, so a single Carney funnel physically supports two published methods: B964 for flow rate (FRC) and B417 for apparent density [S3][S8]. WMT&R's commercial characterisation line lists B212 (Hall apparent density), B213 (Hall flow), B417 (Carney apparent density) and B964 (Carney flow) as a connected quartet, with Carney variants only deployed when Hall data is unattainable [S4].
Funnel geometry, sample mass and the timing tolerance
The Carney funnel's defining feature is a larger discharge orifice than the Hall funnel, sized to let cohesive lots empty under gravity rather than choking in the throat. The Carney funnel specified for B417 uses a 5 mm orifice, and the same body geometry is referenced for B964 flow-rate timing [S8]. A weighed mass of powder is charged into the funnel, started through the orifice, and the elapsed time for the bulk to discharge is recorded; the result is reported as FRC in seconds per 50 g (or per the nominal sample mass defined in the method), with the timing instrument resolution set so the reading is the dominant error source [S4]. Sample preparation is identical in spirit to the Hall method: condition the powder to remove moisture and stearate variability, because the test explicitly notes that moisture, oils, stearic acid, stearates, waxes and the powder's own temperature shift flow behaviour and skew the timing [S3].
Hall vs Carney vs Gustavsson: a side-by-side selection table
The right funnel is a function of the powder, not the analyst's preference. The following comparison lines up the practical decision points a process engineer faces when writing a powder-acceptance procedure. [S2]
Hall (B213) is the default for free-flowing pressed-and-sintered grades, uses a 2.54 mm orifice, and reports flow rate as FRH in seconds per 50 g. Carney (B964) is the fallback for non-free-flowing lots that stall in the Hall throat, uses a larger orifice, and reports FRC. The Carney body also drives ASTM B417 apparent density (ADC) at a 5 mm orifice, so the same hardware covers two test outputs [S4][S8]. Gustavsson funnels, common in additive manufacturing labs, have a different geometry again and are less standardised, sitting outside the B213/B964 pair; they are useful for AM-specific PSD cuts but do not replace B964 for press-shop QC [S10]. A separate Carney-related test, ASTM B417, also covers apparent density with a 5 mm orifice on the same hardware [S8]. For an adjacent view of how powder characterisation feeds into process windows in metal materials selection, the B822 light-scattering PSD update is a natural reference point.
Who should use B964, and who should not
B964 is for incoming-lot QC at a press-and-sinter plant that handles a mix of grades, including the irregular, dendritic, oxide-rich or binder-lubricated powders that stall a Hall funnel. It is also for additive manufacturing labs that need a consensus reference number when reporting FRC for a non-free-flowing AM powder, and for tool-steel and stainless producers running cohesive water-atomised grades [S7]. It is not for free-flowing gas-atomised grades that already pass B213, and it is not a substitute for dynamic flow testing: Carney is a gravity-flow timing test, and high FRC values correlate only loosely with behaviour in a real die cavity or LPBF recoater [S2][S10]. NIST's 2012 review of metal powder testing for AM still treats Carney/Hall data as a screening metric rather than a process predictor, and the field has continued to layer dynamic and shear-cell methods on top [S2]. For applications where powder properties translate into the finished metal material part, the dynamic methods and the B964 result should be reviewed together.
Interlab precision, common failure modes and traceability
Two operational issues drive most out-of-spec FRC numbers. First, powder conditioning: the same lot measured with and without the standard moisture/stearate equilibration can swing flow time enough to fail incoming QC, because surface contamination directly alters interparticle friction [S3]. Second, funnel wear and cleaning: the Carney orifice is larger than Hall's, but a nicked or partially blocked orifice changes effective diameter and ruins the timing. WMT&R lists B964 as part of a 45–850 µm characterisation package alongside ASTM B214 sieve analysis, signalling that most commercial labs run B964 inside a wider battery rather than as a standalone release test [S4]. Hoeganaes' accredited test-method scope likewise pairs Carney flow and Carney apparent density under one accreditation, which is the structure most plants should mirror on their QC SOPs [S6]. For plants already running ASTM B213 in parallel, the simplest change-control is to add B964 as a conditional fallback triggered by a B213 no-flow result, with B417 picked up automatically for apparent density on the same sample.
Standards landscape and 2026 sourcing signals
The 2025-05-08 update to B964 is the current active revision as of 2026-09-21, and ASTM's Committee B09 on Metal Powders and Metal Powder Products owns both B964 and B417 [S1][S3]. B964 is referenced in academic work on cohesive steel and tool-steel powders, where the Carney result is treated as the cohesive-powder counterpart to a Hall reading and feeds into flowability-comparison studies that pair FRC with dynamic and shear-cell data [S7]. Copley Scientific's PTW powder-testing workstation lists Carney flowmeter methods inside a metal-powder-flow module, confirming that commercial instrument vendors continue to support B964 alongside Hall methods rather than replacing it [S9]. For powder-acceptance SOPs being written or revised in late 2026, the actionable signals are: confirm B964-25 is the cited revision, ensure the Carney hardware is calibrated against the 5 mm orifice dimension used for B417 to keep FRC and ADC directly comparable on the same lot, and gate B964 execution behind a documented B213 no-flow result so the more labour-intensive Carney test is only run when justified [S1][S4].
Trackable next nodes: ASTM Committee B09 ballot activity on any future Carney geometry revision, and any interlaboratory study data published in 2026–2027 on FRC reproducibility for binder-treated AM powders. The parallel evolution of ASTM F3049-14(2021) for AM powder characterisation will also shape how B964 FRC values are reported alongside PSD and morphology data on the same lot [S3]. For plants working through the wider metal-powder characterisation stack, the ASTM B822 light-scattering PSD update is the most relevant adjacent read, and the ASTM A532 high-chromium white iron classes, hardness ranges and where each fits piece shows how downstream metal materials specs consume the powder data upstream.
Detailed specification references: metal curtain wall panel.