Steel grit blasting media

Identity and related media

Ervin’s AMASTEEL G40 passes the 1.00 mm sieve, with cumulative minima of 70% at 0.425 mm and 80% at 0.300 mm. G80 passes 0.425 mm, with minima of 65% at 0.180 mm and 75% at 0.125 mm. AMASTEEL technical sheet These are cumulative retained mass percentages. W Abrasives makes its angular grit by crushing heat-treated cast-steel shot. W Abrasives, standard series, July 26, 2022

The word grit alone does not identify the alloy, manufacturing route, hardness, or size distribution. These distinctions matter:

Exact-product properties

The following comparison describes manufacturer literature, not measurements on a supplied lot. Percentages are the chemical-analysis values printed by each manufacturer. The sheets do not provide a complete elemental balance or a lot certificate.

Angular describes the product form, not perfect particle uniformity. Ervin's grit sheet allows at most 5% round or half-round particles for hard grits and 10% for soft grits. It does not define that hardness split. AMASTEEL grit technical data sheet.

GRITTAL's sheet is a general description subject to change. It cites a manufacturer standard based on ISO 11124, ISO 11125, and ISO 6507 without editions. GRITTAL GH data sheet.

As explanatory synthesis, neither an alloy name nor a microstructure description establishes a complete heat-treatment schedule or phase fraction.

The AMASTEEL SDS has a broader product scope than the grit sheet. Section 3 lists Mn 0.35-1.20%, Si 0.40-1.50%, and nickel below 0.2%. Section 9 gives density 7.8 g/cm³ at 20 °C. Those statements do not replace the grit-specific manganese range or establish a bulk density. The documents provide no common density test basis that resolves the different printed values. AMASTEEL US SDS, printed January 15, 2023, reviewed May 11, 2022, sections 3 and 9.

Hardness grades and measurement

Hardness codes belong to the stated product system. AMASTEEL S, M, L, and H hardness ranges are 40-51, 47-56, 54-61, and at least 60 HRC respectively. Ervin's S hardness is separate from an S-prefixed shot size, and its H hardness is separate from a G-prefixed grit size. W Abrasives uses GP, GL, and GH for its standard grit descriptions. These labels do not establish a universal alloy, finish, or microstructure across suppliers. Ervin AMASTEEL specifications, W Abrasives standard series.

HRC denotes the Rockwell C scale and HV denotes Vickers hardness. A paired supplier value is not permission to convert every particle result between scales. Ervin's European brochure pairs its S, M, and L ranges with 390-530 HV, 470-610 HV, and 570-720 HV respectively. Its H entry prints ≥60 HRC with 700 HV in parentheses. The brochure supplies no indentation load, dwell time, sample preparation, or distribution of individual results. European AMASTEEL brochure.

Method details can differ even within historical supplier literature. An undated W Abrasives brochure specifies a 1,000 g microhardness load and ten measurements halfway across the particle radius. Its GP, GB, GL, and GH HRC entries are 40-51, 47-56, 54-61, and 60 minimum. Those are that document's values, not a current cross-supplier translation table. W Abrasives brochure, specification table.

ISO 11125-3:2018 specifies a Vickers method for metallic blast-cleaning abrasives. Its public scope says the method is not recommended below 0.3 mm because accurate testing becomes extremely difficult. A hardness claim without its method, load, and applicable particle size leaves a measurement gap. ISO 11125-3:2018, edition 2, confirmed 2024.

Size numbers describe distributions

SAE J444_202306 defines cast-shot and grit size numbers. Its public scope explains that a grit number uses the nominal test-sieve designation with a G prefix. It is not a particle diameter in millimetres. The manufacturer distribution remains necessary to describe the supplied size. SAE J444_202306, revised June 27, 2023.

Two complete grade examples from Ervin's US AMASTEEL grit table are shown below. They are excerpts, not a reproduction of the entire size specification. Ervin's historical screening chart explicitly identifies its percentages as cumulative. AMASTEEL grit technical data sheet, Ervin screening chart, undated manufacturer document hosted by Interlink Supply.

Cumulative retained percentage includes the material on the named sieve and all coarser sieves. The denominator is the test-portion mass, not the number of particles. The two minima overlap and cannot be added. ISO 11125-2 uses sieving and cumulative retained mass relative to the original test portion. ISO 11125-2:2018 public scope, ISO member SIST's public preview, corrected April 2019, clauses 6-7.

As a conditional arithmetic example, a valid 100 g G40 test portion satisfying those limits has at least 80 g cumulatively retained through the 0.300 mm sieve. At most 20 g passes that sieve. The thresholds do not specify an exact 10 g fraction between 0.300 and 0.425 mm. This is a deduction from the cited limits, not a measured lot distribution.

GRITTAL GH40, by contrast, has a listed grain-size interval of 0.400-0.800 mm under its manufacturer's system. The sheet does not state retained-mass thresholds or oversize and undersize tolerances. GH40 is therefore not an SAE G40 equivalence. GRITTAL GH data sheet.

Density and the working abrasive mix

Density has a volume basis. Particle or material density concerns the abrasive itself. Bulk density includes spaces between particles in a container. Numerically, 1 g/cm³ equals 1 kg/dm³ or 1,000 kg/m³, but matching units does not make these properties interchangeable. This is dimensional explanation, not a packing model or a machine-charge calculation.

New grit and a circulating working mix also differ. W Abrasives says its GP rounds rapidly and GL loses sharp edges in use. It describes GH as retaining angularity in its operating mix. These are product descriptions without matched conditions or a quantified reuse-life limit. They do not establish that every steel grit retains its initial shape. W Abrasives standard series.

ISO 11124-3:2018 explicitly covers abrasives supplied new, excluding media during and after use. Thus, a new-media size or hardness specification alone does not establish the condition of recovered abrasive. This is a scope deduction, not a prescribed recovery setting. ISO 11124-3:2018.

Surface condition and process limits

A grit designation does not certify a cleaned workpiece. Surface profile, remaining contamination, and coating performance are different outcomes. Ervin lists air blasting and centrifugal wheel blasting among AMASTEEL applications, but its product page supplies no universal operating condition or acceptance result. The literature here does not establish a pressure, wheel speed, angle, distance, reuse count, profile depth, cleanliness class, or coating-adhesion guarantee. AMASTEEL grit applications.

Carbon-steel contamination is consequential on stainless workpieces. VULKAN INOX describes foreign iron deposited or embedded during blasting, including from contaminated media circuits, as a source of subsequent rust staining. Stainless grit does not by its name certify an uncontaminated machine or a surface free of embedded particles. VULKAN INOX, iron contamination.

Safety and environmental claims have the same evidence boundary. AMASTEEL's SDS distinguishes the supplied product from fine waste dust and contamination generated during blasting, which it identifies as a possible fire or explosion risk. Its ecological section contains substantial missing data. The SDS does not establish that spent media, removed coatings, dust, or wastewater are harmless or suitable for unrestricted disposal. AMASTEEL SDS, sections 5, 12, 13, and 16.

Standard versions and coverage

ISO lists ISO 11124-3:2018, edition 2, as current and confirmed in 2024. It covers new high-carbon cast-steel shot and grit properties. SAE's public catalog lists J1993_202610, reaffirmed October 2, 2026, for high-carbon cast-steel grit chemistry and physical characteristics. J444_202306 addresses cast-shot and grit sizing. A supplier sheet naming only "J1993" or "J444" does not identify which edition underlies that sheet. ISO 11124-3 catalog, SAE J1993_202610 catalog, SAE J444_202306 catalog.

Coverage comprises the cited manufacturer sheets, the full AMASTEEL SDS, and public standard scopes and the cited public sieve-method preview. The Ervin sheets and historical screening chart have no visible revision date. GRITTAL's sheet is dated October 2022. No lot certificate, controlled blasting trial, recovered-media analysis, or customer process qualification supports this reference. General product properties remain separate from measured lot properties and accepted workpiece requirements.