Engineering ToolBox - Resources, Tools and Basic Information for Engineering and Design of Technical Applications!

This is an AMP page - Open full page! for all features.

• the most efficient way to navigate the Engineering ToolBox!

# Threaded Bolts - Stress Area

The weakest points in a bolt is the stressed area in the thread root. The stressed area depends on the type of threads - coarse threads reduces the stressed area compared to fine threads.

### UN and UNR Bolts Tensile Stress Area

The stressed area in a bolt can be calculated as

A = (π / 4)  (dn - 0.9743/ n)2                                      (1)

where

A = stressed area (in2)

dn = nominal bolt diameter (in)

n = 1 / p = number of threads per inch

p = pitch, length per thread (in)

Despite that a reduced area will reduce the breaking load of a bolt - coarse threads are used for clamping. Fine threads bolts are weaker due to the reduced thread height.

### ISO 898 Bolts Tensile Stress Area

Tensile stress area in bolts according ISO 898-1 Mechanical properties of fasteners made of carbon steel and alloy steel:

As,nom = (π / 4) ((d2 + d3)/ 2)2                        (2)

where

As,nom = nominal stress area (m, mm2)

d2 = the basic pitch diameter of the external thread according ISO 724 ISO general-purpose metric screw threads -- Basic dimensions (m, mm)

d3 = d1 - H / 6 = the minor diameter of external tread (m, mm)

d1 = the basic minor diameter of external thread according ISO 724

H = the height of the fundamental triangle of the thread according ISO 68-1 ISO general purpose screw threads (m, mm)

### Materials

Most bolts are made of medium or low carbon steel. Forges bolts are called "black" and machined bolts are called "bright". Other materials used are high tensile steel (HT bolts), stainless steel, alloy steel, brass and other materials.

Threads are formed by cutting or rolling.

## Related Topics

### • Miscellaneous

Engineering related topics like Beaufort Wind Scale, CE-marking, drawing standards and more.

## Related Documents

### Bolt Stretching and Tensile Stress

Tensile stress and Hooke's Law.

### Bolt Torque Calculator

Calculate required bolt torque.

### ISO 724 - Metric Threads

Dimensions of metric threads according ISO 724.

### Metric Bolt Heads and Wrench Sizes

ANSI/SO, DIN and JIS bolts.

### Metric Bolts - Minimum Ultimate Tensile and Proof Loads

Minimum ultimate tensile and proof loads for metric bolts with coarse or fine threads.

### Metric Bolts - Tightening Torques

Recommended thightening torque metric bolts.

### Metric Steel Bolts - Grades and Property Classes

Metric steel bolts, screws and studs - proof and tensile strength.

### Reduced Torque with Lubricated Bolts

Lubrication effect on bolt tension and torque.

### Steel Bolts - ASTM Grades

ASTM steel bolts - proof and tensile strength.

### Steel Bolts - SAE Grades

SAE steel bolts - grades ranging grade 1 to 8.2 - proof and tensile strength.

### Steels - Endurance Limits and Fatigue Stress

Endurance limits and fatigue stress for steels.

### Stress

Stress is force applied on cross-sectional area.

### Stress, Strain and Young's Modulus

Stress is force per unit area - strain is the deformation of a solid due to stress.

### Thermoplastics - Physical Properties

Physical properties of thermoplastics like ABS, PVC, CPVC, PE, PEX, PB and PVDF.

### UNC and UNF - Unified Coarce and Unified Fine Inch Threads

ANSI/ASME B1.1 Unified National Thread - UNC Coarse series and UNF Fine series.

### US Bolts - Tensile Strength and Proof Loads

Tensile strength and proof loads SAE bolts.

### Wrench Spanners - Inches vs. mm

Convert between US Inches and metric mm wrench and spanner sizes.

### Young's Modulus, Tensile Strength and Yield Strength Values for some Materials

Young's Modulus (or Tensile Modulus alt. Modulus of Elasticity) and Ultimate Tensile Strength and Yield Strength for materials like steel, glass, wood and many more.

## Search Engineering ToolBox

• the most efficient way to navigate the Engineering ToolBox!

## SketchUp Extension - Online 3D modeling!

Add standard and customized parametric components - like flange beams, lumbers, piping, stairs and more - to your Sketchup model with the Engineering ToolBox - SketchUp Extension - enabled for use with the amazing, fun and free SketchUp Make and SketchUp Pro . Add the Engineering ToolBox extension to your SketchUp from the Sketchup Extension Warehouse!