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ISO 898-1
Mechanical Properties of Bolts, Screws and Studs

Universal Grip ISO 898-1 full-size bolt and screw tensile fixture

Downloads: ISO 898-1 Full-Size Bolt and Screw Tensile Fixture – Universal Grip Data Sheet (PDF)

Written by Chris Thomas, Universal Grip Company · Reviewed by Frank Bertini · Updated October 24, 2026

ISO 898-1 is the international standard that defines the mechanical and physical properties of carbon steel and alloy steel bolts, screws and studs, and the tests that prove them. It is the standard behind the 8.8, 10.9 and 12.9 markings on a bolt head: the property class system, the minimum tensile strength, yield and proof stress for each class, the minimum ultimate tensile loads and proof loads for every thread size from M1.6 to M39, and the full-size tests, wedge tests, proof-load tests, machined-specimen tests, hardness tests and head-soundness tests that a fastener maker or an incoming-inspection lab runs to certify a lot. Its companion ISO 898-2 covers nuts, ISO 3506-1 covers stainless fasteners and the ASTM equivalent is F606/F606M.

This guide covers the current edition, ISO 898-1:2013 with its corrigendum, the scope; the property-class designation and the key values of Table 3 for every class; the minimum ultimate tensile loads and proof loads for M6 to M36 in classes 8.8, 10.9 and 12.9, which decide what machine and fixture you need; each test method with its numbers (free thread length, speeds, hold times, wedge angles, permanent-set limits); worked examples; the fixture anatomy and capacity selection; a numeric comparison with ASTM F606 practice and SAE J429; and the full-size bolt tensile fixture, bolt grips and machines Universal Grip supplies. The metals testing page covers the companion ISO 6892-1 tensile test on machined specimens, and the ISO standards hub lists every ISO method we equip.

In this guide: What ISO 898-1 Covers · Editions and Related Standards · Property Classes and Table 3 · Minimum Ultimate Tensile Loads and Proof Loads · The Tests: Clause 9 Methods and Their Numbers · Worked Examples · Fixture Anatomy and Capacity Selection · Common Errors and How Big They Are · ISO 898-1 vs ASTM F606/F606M and SAE J429 · Equipment for ISO 898-1: Fixture, Grips and Machines · FAQ

What ISO 898-1 Covers

ISO 898-1 specifies the mechanical and physical properties of bolts, screws and studs made of carbon steel and alloy steel, with ISO metric triangular thread in coarse pitches M1.6 to M39 and fine pitches M8×1 to M39×3, tested at ambient temperature of 10 °C to 35 °C. The fasteners are intended for service from −50 °C to +150 °C (to +300 °C with a metallurgist's agreement; Annex B is informative on elevated temperature). Several things are outside its scope: set screws and similar threaded fasteners not under tensile stress (ISO 898-5), weldability, corrosion resistance, shear strength, torque and clamp-force relationships (ISO 16047) and fatigue. Fasteners with low or countersunk heads may not meet the tensile or torsional requirements because the head is the weak link, and the standard says so. Stainless steel fasteners go to ISO 3506-1 and nuts to ISO 898-2:2022; torsional testing of M1 to M10 screws is in ISO 898-7.

Most tests are run on the finished fastener, full size, loaded through its own head and thread, so the result includes the thread form, the head fillet, the heat treatment and any plating. Machined test pieces turned from the shank are used only where a full-size test is not possible or when the material properties themselves are wanted, which is what separates this from a conventional ISO 6892-1 tensile test and why a dedicated fixture is needed.

Editions and Related Standards

  • ISO 898-1:2013 (fifth edition, January 2013) plus Technical Corrigendum 1:2013 is the current edition. It is a minor revision of the 2009 fourth edition, which was the major rewrite: it removed the obsolete class 3.6, re-ordered the test clauses, introduced the underlined 12.9 variant with its note on stress-corrosion sensitivity and added the reduced-loadability designation (a leading zero, for example 08.8).

  • ISO 898-2:2022 gives the proof-load values and hardness for nuts of the matching classes (8, 10, 12 and the others) and is tested on the same fixture with a hardened mandrel in place of the bolt.

  • ISO 3506-1 covers corrosion-resistant stainless steel bolts and screws (A2-70, A4-80 and the rest) with its own property classes.

  • ASTM F606/F606M is the ASTM test-method standard for fasteners (the test procedures only; strength values come from the product specifications such as ASTM A307, F1554 and SAE J429).

ISO 898-1:2013 splits class 8.8 by diameter (d ≤ 16 mm and d > 16 mm) with different minimum values, which matters for certifying structural bolts from M20 to M36; several equipment pages still show one 8.8 row and the obsolete class 3.6.

Property Classes and Table 3

A property class is two numbers separated by a point. The first is one hundredth of the nominal tensile strength in MPa; the second is ten times the ratio of yield (or 0.2 % proof) stress to tensile strength. So 8.8 means a nominal tensile strength of 800 MPa and a yield of 0.8 × 800 = 640 MPa; 10.9 means 1,000 MPa and 900 MPa; 12.9 means 1,200 MPa and 1,080 MPa. The classes in ISO 898-1:2013 are 4.6, 4.8, 5.6, 5.8, 6.8, 8.8, 9.8, 10.9 and 12.9, the last also available as the underlined 12.9 variant whose footnote warns about stress-corrosion sensitivity. The class may be applied above M39 if the Table 2 and Table 3 values are met. Table 3 gives the minimum (and for tensile strength also the nominal) values for each class; the rows that matter most in a test lab are:

  • 8.8, d ≤ 16 mm: Rm 800 / 800 MPa; Rp0.2 640 MPa; Sp 580 MPa; A 12 %; reduction of area Z 52 %; 250 to 320 HV (22 to 32 HRC).

  • 8.8, d > 16 mm: Rm 800 / 830 MPa; Rp0.2 660 MPa; Sp 600 MPa; A 12 %; Z 52 %; 255 to 335 HV (23 to 34 HRC).

  • 10.9: Rm 1,000 / 1,040 MPa; Rp0.2 940 MPa; Sp 830 MPa; A 9 %; Z 48 %; 320 to 380 HV (32 to 39 HRC).

  • 12.9: Rm 1,200 / 1,220 MPa; Rp0.2 1,100 MPa; Sp 970 MPa; A 8 %; Z 44 %; 385 to 435 HV (39 to 44 HRC).

Lower classes 4.6, 5.6 and 9.8 follow the same pattern (Rm 400 / 500 / 900 MPa). Surface hardness at HV 0.3 may not exceed the core by more than 30 HV, and the wedge and head-soundness tests must meet the same Rm minimum as the plain tensile test.

Minimum Ultimate Tensile Loads and Proof Loads

The lab works in newtons, not megapascals. Table 4 (coarse thread) converts the Table 3 minimum tensile strength into a minimum ultimate tensile load Fm,min for each size, using the nominal stress area As,nom = 0.7854 × [(d2 + d3)/2]², and Table 5 does the same for the proof load Fp. These are the loads the fixture, the load cell and the frame must reach, and the list below (coarse thread, in kN) is the one to size a system from:

  • M6 (As 20.1 mm²): 8.8 → Fm,min 16.1 kN, Fp 11.6 kN; 10.9 → 20.9 / 16.7 kN; 12.9 → 24.5 / 19.5 kN.

  • M8 (36.6 mm²): 8.8 → 29.2 / 21.2 kN; 10.9 → 38.1 / 30.4 kN; 12.9 → 44.6 / 35.5 kN.

  • M10 (58.0 mm²): 8.8 → 46.4 / 33.7 kN; 10.9 → 60.3 / 48.1 kN; 12.9 → 70.8 / 56.3 kN.

  • M12 (84.3 mm²): 8.8 → 67.4 / 48.9 kN; 10.9 → 87.7 / 70.0 kN; 12.9 → 103 / 81.8 kN.

  • M16 (157 mm²): 8.8 → 125 / 91.0 kN; 10.9 → 163 / 130 kN; 12.9 → 192 / 152 kN.

  • M20 (245 mm²): 8.8 → 203 / 147 kN; 10.9 → 255 / 203 kN; 12.9 → 299 / 238 kN.

  • M24 (353 mm²): 8.8 → 293 / 212 kN; 10.9 → 367 / 293 kN; 12.9 → 431 / 342 kN.

  • M30 (561 mm²): 8.8 → 466 / 337 kN; 10.9 → 583 / 466 kN; 12.9 → 684 / 544 kN.

  • M36 (817 mm²): 8.8 → 678 / 490 kN; 10.9 → 850 / 678 kN; 12.9 → 997 / 792 kN.

Fine-pitch threads have a larger stress area: M24×2 in 12.9 needs 469 kN and M36×3 in 12.9 needs 1,055 kN. The arithmetic is simple to check: M10 10.9 is 58.0 mm² × 1,040 MPa = 60.3 kN, and M24 12.9 is 353 mm² × 1,220 MPa = 431 kN. A real bolt usually breaks 5 to 15 % above the minimum, so the frame needs headroom above these numbers.

The Tests: Clause 9 Methods and Their Numbers

Tensile test on finished bolts, screws and studs (9.2)

The fastener is loaded axially in a fixture that bears on the underside of the head and engages the thread in a hardened internally threaded adaptor (hardness ≥ 45 HRC). The length of free, unengaged thread between the adaptor and the head bearing must be at least 1d (1.2d when the test is combined with the elongation measurement of 9.3), and the thread engagement in the adaptor at least 1d. The crosshead speed must not exceed 25 mm/min, and the load is taken to fracture. The tensile strength Rm = Fm / As,nom must meet Table 3, equivalently Fm must reach Table 4's Fm,min. The fracture must occur in the free thread or the shank; a fracture in the head or at the head-to-shank transition is a failure regardless of load. Full-size tensile tests apply to 3 ≤ d ≤ 39 mm with a length l ≥ 2.5d; shorter parts and larger diameters use machined pieces or, for very short parts, hardness alone.

Wedge loading test (9.1)

The same tensile test with a hardened wedge washer (≥ 45 HRC, angle held to ±30′) under the head, so that the head is loaded obliquely and the head-to-shank fillet is put in bending as well as tension. It is the test that catches a poorly formed fillet, a decarburized head or a quench crack under the head. The wedge angle depends on the class, the diameter and whether the bolt has an unthreaded shank:

  • Shank length ls ≥ 2d, classes 4.6 to 10.9: 10° for 3 ≤ d ≤ 20 mm; 6° for 20 < d ≤ 39 mm.

  • Shank length ls ≥ 2d, class 12.9: 6° for d ≤ 20 mm; 4° for d > 20 mm.

  • Shank length ls < 2d (threaded to the head or short shank), classes 4.6 to 10.9: 6° for d ≤ 20 mm; 4° for d > 20 mm.

  • Shank length ls < 2d, class 12.9: 4° for all sizes.

The wedge washer's hole diameter and edge radius are tabulated by size (for M10 a hole of 11 to 11.27 mm with a 0.8 mm radius; for M16 17.5 to 17.77 mm with 1.3 mm). Free thread is again ≥ 1d and speed ≤ 25 mm/min. Pass requires both Fm ≥ Fm,min and fracture in the free thread or shank, not in the head or transition; for bolts threaded to the head the fracture must be in the free thread.

Proof load test (9.6)

The bolt's overall length is measured to ±1 µm resolution (a dial or digital gauge between hardened centres or a flat anvil and a ball), the bolt is loaded in the same fixture with ≥ 1d free thread to the proof load Fp of Table 5 at a speed not exceeding 3 mm/min, held for 15 s, unloaded, and measured again. The length after the test must be within ±12.5 µm of the length before; any apparent permanent extension inside that band is treated as measurement scatter. If a permanent extension is indicated, the test may be repeated at Fp + 3 % and the same ±12.5 µm rule applied. The proof-load test is the non-destructive acceptance test for lots that will go into service, and it is also the routine test on nuts to ISO 898-2.

Elongation after fracture and proof strength on finished bolts (9.3)

For the lower classes 4.8, 5.8 and 6.8, which have no machined-specimen elongation requirement, the test is run with 1.2d of free thread at 10 mm/min to the proof strength then 25 mm/min to fracture. The elongation after fracture Af = ΔLp / 1.2d must meet 0.24 (4.8), 0.22 (5.8) and 0.20 (6.8). The proof strength Rpf is taken at a non-proportional elongation of 0.0048d, which is 0.4 % of the 1.2d free length; it is reported but carries no requirement yet.

Machined test pieces (9.7)

Where the full-size test is not possible, or the material properties are wanted, a round specimen is turned from the shank with a diameter d0 smaller than the minor thread diameter d3,min (preferably d0 ≥ 3 mm), a gauge length L0 = 5d0, fillet radius ≥ 4 mm, and for quenched-and-tempered fasteners over 16 mm the diameter is reduced by no more than 25 % so the test reflects the as-hardened core. The test is run as in ISO 6892-1 at 10 mm/min to yield and 25 mm/min after, and Rm, ReL or Rp0.2, A and Z must meet Table 3. This is the test that proves the 12 % elongation of class 8.8 or the 44 % reduction of area of class 12.9.

Head soundness (9.8) and hardness (9.9)

For screws of d ≤ 10 mm too short for a wedge test (l ≥ 1.5d), the head is struck in a hardened block (≥ 45 HRC, ≥ 2d thick, Table 15 hole and radius) until bent to 90° − β, with β = 60° or 80° by class, and examined at 8 to 10× for cracks at the head-shank junction. Hardness is measured by Vickers, Brinell or Rockwell C on a transverse section through the thread; for fasteners that can be tensile tested it only checks the maximum. Surface hardness at HV 0.3 may not exceed core plus 30 HV; decarburization and carburization are checked by HV 0.3 traverses at three depths; Charpy impact (ISO 148-1) applies to d ≥ 16 mm when required.

Worked Examples

  • M10 × 1.5 class 10.9 hex bolt, 60 mm long, 26 mm shank. As,nom = 58.0 mm²; Fm,min = 58.0 × 1,040 = 60.3 kN; Fp = 58.0 × 830 = 48.1 kN. Shank 26 mm ≥ 2d = 20 mm and d ≤ 20 mm, so the wedge angle is 10°. A tensile result of 65.0 kN gives Rm = 65,000 / 58.0 = 1,121 MPa: pass (≥ 1,040), with the fracture in the free thread. Proof: load to 48.1 kN at ≤ 3 mm/min, hold 15 s, length change 4 µm: pass (≤ 12.5 µm).

  • M24 × 3 class 12.9 socket head cap screw, threaded to the head. As,nom = 353 mm²; Fm,min = 353 × 1,220 = 431 kN; Fp = 353 × 970 = 342 kN. ls < 2d and class 12.9, so the wedge angle is 4°. A 250 kN fixture cannot test it; the job needs a 600 kN or larger frame with ≥ 1d (24 mm) of free thread between the head bearing and the adaptor.

  • M20 class 8.8 structural bolt, 80 mm long. d > 16 mm, so Rm,min = 830 MPa and Sp = 600 MPa: Fm,min = 245 × 830 = 203 kN; Fp = 245 × 600 = 147 kN. Shank ≥ 40 mm and d ≤ 20 mm: wedge 10°. A 250 kN fixture covers it with 23 % headroom.

Fixture Anatomy and Capacity Selection

A full-size bolt test needs a load train that bears on the head and engages the thread without bending the bolt, loads and unloads in seconds, and survives the energy released when a 12.9 fastener fractures at several hundred kilonewtons (guards or an enclosure are normal practice). One end should be self-aligning to keep bending out of the plain tensile test; no extensometer is used, and the proof test uses a length gauge off the machine. The parts are:

  • Open-window housings: two bodies, one for the head end and one for the thread end, with a side window so the bolt is dropped in and the broken halves removed without unscrewing anything from the frame.

  • Head bearing plates: hardened plates with the Table 15 hole and edge radius, sized by thread diameter; the wedge washer sits on or replaces this plate for the wedge test.

  • Thread adaptors: hardened (≥ 45 HRC) internally threaded inserts for each size and pitch, giving ≥ 1d engagement and a controlled free-thread length.

  • Wedge washers: ≥ 45 HRC, ground to 4°, 6° or 10° within ±30′, one per angle and size range, with the hole and radius of Table 15.

Capacity is read straight from the load table plus headroom. A 250 kN fixture and frame cover every size and class up to M16 (M16 12.9 = 192 kN), M20 in 8.8 (203 kN) and M18 in 12.9 (about 234 kN), but not M20 in 10.9 (255 kN) or 12.9 (299 kN). A 600 kN system covers M24 in all classes (431 kN at 12.9) and M30 in 8.8 and 10.9 (466 and 583 kN). 1,000 kN covers M36 in 10.9 (850 kN) comfortably and M36 12.9 (997 kN) with almost no margin, so M36 12.9 and the fine-pitch M36×3 (1,055 kN) belong on a 1,200 or 2,000 kN hydraulic machine. Nuts to ISO 898-2 use the same housings with a hardened test mandrel in place of the bolt.

Common Errors and How Big They Are

  • Wrong wedge angle. Using 10° on a bolt threaded to the head (ls < 2d) when 6° is specified over-tests it; using 6° on a long-shank bolt under-tests it. The angle table is by class, diameter and shank length, all three.

  • Too little free thread. Less than 1d of free thread between the adaptor and the head raises the apparent strength because the thread is supported; the standard requires ≥ 1d (1.2d for the Af test).

  • Soft adaptors or washers. Below 45 HRC the adaptor threads yield and the wedge washer flattens, both of which lower the bending on the head and give a false pass.

  • Speed above 25 mm/min. Fast loading raises the measured strength of carbon steel by a few percent; 25 mm/min is the ceiling for tensile and wedge tests, and 3 mm/min for proof load.

  • Wrong 8.8 row. M20 and above in class 8.8 use Rm 830 MPa and Sp 600 MPa, not the 800/580 of the small sizes; a lab that uses one 8.8 row under-tests large structural bolts by 4 %.

  • Accepting a head fracture at full load. A fracture in the head or at the head-shank transition is a failure in the tensile and wedge tests even when Fm,min is exceeded.

ISO 898-1 vs ASTM F606/F606M and SAE J429

ASTM F606/F606M is the ASTM test-method standard; it does not set strengths, which come from the product specifications (ASTM A307 grades A and B, ASTM F1554 anchor bolts, SAE J429 grades 2, 5 and 8, ASTM A325/A490 structural bolts). SAE J429 Grade 5 requires 120 ksi (827 MPa) tensile, 85 ksi proof and 92 ksi yield up to 1 in, close to ISO 8.8; Grade 8 requires 150 ksi (1,034 MPa) tensile, 120 ksi proof and 130 ksi yield, close to ISO 10.9. The procedures differ in the details that follow:

  • Wedge angles: ISO switches from 10° to 6° at d = 20 mm (6° to 4° for 12.9); F606 switches at 1 in / M24 (10° to 6° for bolts, 6° to 4° for studs and flange bolts). F606's footnote for heat-treated bolts threaded to within 1d of the head uses 6° (M5 to M20) and 4° (above M20), the counterpart of ISO's ls < 2d rule.

  • Free thread: ISO ≥ 1d (1.2d for Af); F606 requires six full threads exposed between the grips (four for heavy-hex structural bolts) and treats bolts shorter than 3d as too short for a full-size test.

  • Speeds: tensile and wedge ≤ 25 mm/min (1 in/min) in both; proof load ≤ 3 mm/min (0.12 in/min) in both.

  • Proof hold and set: ISO holds 15 s and allows ±12.5 µm; F606 Method 1 holds 10 s and allows ±0.013 mm (0.0005 in) after rotating the bolt 360° in the gauge; F606 Method 2 uses a 0.2 % offset yield over six threads and Method 3 a mid-radius versus core hardness check (≤ 3 HRC) up to 1 in / M24.

  • Fracture location: both prohibit head and head-shank-junction fractures at any load.

A fixture built to ISO 898-1 (open housings, 45 HRC adaptors, ±30′ wedge washers at 4°, 6° and 10°) also runs F606; what changes is which washer goes on which bolt, the hold time and the exposed-thread rule, all procedure rather than hardware.

Equipment for ISO 898-1: Fixture, Grips and Machines

Universal Grip ISO 898-1 full-size bolt tensile fixture

Our ISO 898-1 fixture is a tensile fixture set for testing full-size bolts, screws and studs. Open-window housings accept interchangeable thread adapters and head bearing plates sized by thread diameter, so the fastener is loaded axially through its head and engaged thread; wedge washers can be added for wedge loading tests. From the data sheet: open-window housings for fast side loading of fasteners; interchangeable thread adapters and bearing plates marked by thread size; head bearing plates and wedge washers for wedge loading tests; heat-treated alloy steel components for high proof loads; test methods full-size fastener tensile, proof load and wedge loading; axial tension through head and thread; metric bolts, screws and studs with the size range to order; load capacity 250 kN standard, up to 1,000 kN on request; hardened bearing plates, thread adapters and wedge washers as the contact surfaces; threaded or pin adapter to suit the customer frame; compatible with electromechanical and servo-hydraulic universal testing machines. Applications on the sheet: bolts, screws and studs in classes 4.6 to 12.9, fastener manufacturers and distributors, automotive and structural bolting, incoming inspection and lot certification. When ordering, specify thread sizes and pitches, property classes, the wedge angles needed, and the test machine capacity and connection.

The 250 kN standard set covers all sizes through M16 in every class, M18 in 12.9 and M20 in 8.8; M20 in 10.9 and 12.9, M24 and above, and the fine-pitch large sizes go to the higher-capacity version. Wedge washers are supplied at the angles your mix of classes and shank lengths needs; most labs that certify 8.8, 10.9 and 12.9 need all three of 10°, 6° and 4°. For ISO 898-2 nut proof-load tests we add a hardened test mandrel. Our bolt grips are the alternative for bolts tested in a tensile frame with standard couplings and for threaded rod and studs, and the grip adapters page lists the clevis and thread sizes we fit to Instron, MTS, ZwickRoell, Shimadzu, Tinius Olsen and Galdabini frames.

Machines

Size the frame from the load table with 20 to 30 % headroom. A 200 kN floor-standing UTM with the 250 kN fixture covers M6 to M16 in all classes and M20 in 8.8; a 600 kN frame covers M24 in 12.9 and M30 in 10.9; a 1,000 kN machine covers M36 10.9 and, with no margin, M36 12.9; and the hydraulic machines at 1,200 to 2,000 kN cover M36 12.9, fine-pitch M36×3 and anything above M39 tested full size. All need a speed range that includes ≤ 3 mm/min for proof load and 25 mm/min for the tensile and wedge tests, a daylight that takes the two housings plus the longest bolt, and guarding for the fracture of high-class fasteners. The machined-specimen test is a conventional ISO 6892-1 tensile test with wedge grips and an extensometer, and the rebar and steel testing post covers the related structural-steel tests.

ISO 898-1 FAQ

What is ISO 898-1?

The international standard for the mechanical and physical properties of carbon steel and alloy steel bolts, screws and studs with specified property classes (4.6 to 12.9), coarse thread M1.6 to M39 and fine pitch M8×1 to M39×3. It sets the strength values and the test methods: full-size tensile, wedge, proof load, machined specimen, hardness and head soundness. The current edition is ISO 898-1:2013 with Corrigendum 1.

What do the numbers in a property class like 8.8 or 10.9 mean?

The first number is one hundredth of the nominal tensile strength in MPa and the second is ten times the yield-to-tensile ratio. 8.8 is 800 MPa tensile and 640 MPa yield; 10.9 is 1,000 (minimum 1,040) MPa and 940 MPa; 12.9 is 1,200 (minimum 1,220) MPa and 1,100 MPa. Class 8.8 above 16 mm uses a higher minimum of 830 MPa.

What is the minimum ultimate tensile load for an M24 12.9 bolt?

431 kN, from the stress area of 353 mm² times the 1,220 MPa minimum tensile strength; the proof load is 342 kN. An M24 10.9 needs 367 kN and an M24 8.8 needs 293 kN. An M36 12.9 needs 997 kN.

What wedge angle does ISO 898-1 use?

For bolts with a shank of at least 2d: 10° up to M20 and 6° above M20 for classes 4.6 to 10.9, and 6° / 4° for class 12.9. For bolts threaded to the head or with a shank shorter than 2d: 6° / 4° for 4.6 to 10.9 and 4° throughout for 12.9. The wedge is hardened to at least 45 HRC with the angle held to ±30 minutes.

How is the proof load test done in ISO 898-1?

Measure the bolt length to 1 µm, load it with at least 1d of free thread to the proof load Fp at no more than 3 mm/min, hold for 15 s, unload and re-measure. The length must be within ±12.5 µm of the original. If a permanent extension is indicated, the test may be repeated at Fp + 3 % with the same limit.

What test speed does ISO 898-1 allow?

Not more than 25 mm/min for the full-size tensile and wedge tests, not more than 3 mm/min for the proof-load test, and 10 mm/min up to yield then 25 mm/min for machined test pieces and for the elongation test on finished bolts.

How much free thread is required in an ISO 898-1 tensile test?

At least one thread diameter (1d) of unengaged thread between the adaptor and the head bearing, and at least 1d of engagement in the hardened (≥ 45 HRC) adaptor. The elongation test on finished bolts of classes 4.8, 5.8 and 6.8 uses 1.2d.

Where must an ISO 898-1 bolt fracture?

In the free thread or in the shank. A fracture in the head or at the head-to-shank transition is a failure in both the tensile and wedge tests even if the minimum load was reached. Bolts threaded to the head must fracture in the free thread.

When are machined test pieces used in ISO 898-1?

When a full-size test is not possible (diameter over 39 mm, short parts, special heads) or when the material properties Rm, Rp0.2, A and Z are required. The piece is turned from the shank with d0 below the minor thread diameter, L0 = 5d0, a 4 mm fillet and no more than 25 % diameter reduction for quenched-and-tempered fasteners over 16 mm.

What is the difference between ISO 898-1 and ASTM F606?

F606/F606M gives only the test methods; strengths come from product specifications such as A307, F1554 and SAE J429. F606 switches wedge angles at M24 / 1 in rather than M20, requires six exposed threads rather than 1d, holds the proof load 10 s rather than 15 s, and allows ±0.013 mm permanent set. Speeds (25 and 3 mm/min), 45 HRC wedges and the head-fracture prohibition are the same.

What machine capacity is needed for ISO 898-1 testing?

Take the minimum ultimate tensile load for the largest size and class and add 20 to 30 %. A 250 kN fixture on a 200 to 300 kN frame covers through M16 in all classes and M20 in 8.8; 600 kN covers M24 12.9 (431 kN); 1,000 kN covers M36 10.9 (850 kN) and barely M36 12.9 (997 kN); fine-pitch M36×3 12.9 (1,055 kN) needs a larger hydraulic machine.

What hardness does ISO 898-1 require?

Core hardness ranges by class, for example 250 to 320 HV for 8.8 (d ≤ 16), 320 to 380 HV for 10.9 and 385 to 435 HV for 12.9, measured by Vickers, Brinell or Rockwell C on a transverse section. Surface hardness at HV 0.3 may not exceed the core by more than 30 HV, which is the check against carburization.

Need a full-size bolt tensile fixture, wedge washers, thread adapters or a complete fastener testing system for ISO 898-1? Contact Universal Grip with your thread sizes, property classes, wedge angles and machine capacity and we will quote the right set.

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