Property Class 8.8 Steel Left-Hand Thread Hex Bolts are supplied to ISO 898-1 property class 8.8. Corrosion behaviour is requires plating (zinc) for corrosion protection, the material is magnetic, and the usable service range is commonly limited to approx. +300 °C; confirm against the coating and the load. In practice this grade is the workhorse medium-carbon alloy class for structural joints.
- Grade
- ISO 898-1 property class 8.8
- Corrosion resistance
- Requires plating (zinc) for corrosion protection
- Magnetic response
- Magnetic
- Service temperature
- commonly limited to approx. +300 °C; confirm against the coating and the load
Property values are typical for the grade. Certified mechanical test data is available on request for production orders.
Left-Hand Thread Hex Bolts manufactured in Property Class 8.8 Steel (ISO 898-1 property class 8.8) are dimensioned to DIN 933. The sections below give the mechanical and physical properties of the grade, its behavior in corrosive and elevated-temperature service, and the full size table.
Why Choose Property Class 8.8 Steel for Left-Hand Thread Hex Bolts
The workhorse medium-carbon alloy class for structural joints. For left-hand thread hex bolts, this matters when requires plating (zinc) for corrosion protection is the primary requirement.
Mechanical & Physical Properties
| Grade designation | ISO 898-1 property class 8.8 |
|---|
| Magnetic response | Magnetic |
|---|
| Service temperature | commonly limited to approx. +300 °C; confirm against the coating and the load |
|---|
| Corrosion characteristic | Requires plating (zinc) for corrosion protection |
|---|
Corrosion Behavior in Service
Carbon and alloy steel left-hand thread hex bolts require a coating for corrosion protection. Zinc plating (with or without passivation) is the most common; hot-dip galvanizing is used for outdoor structural service; black-oxide is mainly a tarnish-prevention finish for tool-room use.
Comparable Grades
For Left-Hand Thread Hex Bolts, class 10.9 or 12.9 is the comparable strength step. Move up when the joint preload approaches the proof load of the current class; move down when the joint is over-specified. For corrosion-critical service, switch to stainless A2 or A4.
Sizes of Left-Hand Thread Hex Bolts Available in Property Class 8.8 Steel
| Thread size | Pitch (mm) | Across flats s (mm) | Across corners e (mm) | Head height k (mm) | Thread direction | Common length range (mm) | Reference standard |
|---|
| M6 | 1.0 | 10 | 11.05 | 4.0 | Left-hand | 10~60 | DIN 933 LH |
| M8 | 1.25 | 13 | 14.38 | 5.3 | Left-hand | 12~80 | DIN 933 LH |
| M10 | 1.5 | 17 | 18.90 | 6.4 | Left-hand | 16~100 | DIN 933 LH |
| M12 | 1.75 | 19 | 21.10 | 7.5 | Left-hand | 20~120 | DIN 933 LH |
| M16 | 2.0 | 24 | 26.75 | 10.0 | Left-hand | 25~150 | DIN 933 LH |
| M20 | 2.5 | 30 | 33.53 | 12.5 | Left-hand | 30~150 | DIN 933 LH |
| M24 | 3.0 | 36 | 39.98 | 15.0 | Left-hand | 40~150 | DIN 933 LH |
Dimensions are independent of the material: every size above is available in Property Class 8.8 Steel.
Custom manufacturing · Made to drawing
Need this bolt in a grade that is not listed?
Grade 8 8 Steel is one of the grades the catalog describes. Where the standard stops, the drawing takes over: fine pitches, left-hand threads, partial threading, and property classes above the catalogued grade where material and heat treatment allow. Made by cold heading or hot forging.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
Custom bolt manufacturingSend a drawing
Applications & Industries
Left-Hand Thread Hex Bolts are bought for a small number of well-defined jobs. These are the ones we ship them for. Stocked from M6 to M24.
Industries that specify Left-Hand Thread Hex Bolts
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Automotive & transport
Chassis, driveline and body fixings that see vibration and are assembled to a controlled preload.
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Steel fabrication
Bolted connections in frames, enclosures, walkways and weldments, on the bench and on site.
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Energy & infrastructure
Tower, pipework, switchgear and plant fixings specified for long service life and inspectable joints.
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Maintenance & MRO
Stocked replacements matched to an existing property class, thread and finish.
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Food, pharma & cleanroom
Stainless assemblies that are washed down, where the finish matters as much as the strength.
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Machine building & OEM
The default fastener on production equipment: covers, brackets, motor mounts and sub-assemblies tightened to a specified torque.
Typical applications
- joints where the property class is stated on the drawing
- clamping two machined faces to a calculated preload
- bolting brackets, motors and gearboxes to a frame
- assemblies that are dismantled for service and re-torqued
Service conditions to specify against
- Marine and coastal
- Available in A4 (316) stainless for chloride exposure — coastal structures, pool halls, water treatment and deck hardware, where A2 will eventually pit.
- High load
- Supplied in ISO 898-1 property classes, so the joint can be designed to a stated proof load and tightened to a calculated torque rather than by feel.
- Torque and preload
- The joint is designed around bolt tension, so lubrication, coating and the friction coefficient all change the torque figure — state them together.
Where to use something else
- Do not use a machine thread into unthreaded sheet or timber; use a tapping screw, rivet nut or insert made for that parent material.
Full application guide: where Left-Hand Thread Hex Bolts are used, how to specify them, and the cases they are wrong for
