Grade 5 Square Head Bolt

Material characteristics

The core material characteristics of Grade 5 square head bolt can be summarized as:

（1）Base material: Medium Carbon Steel, with carbon content ranging from 0.28% to 0.55%.

（2）Heat treatment condition: It must undergo quenching followed by tempering treatment to meet the mechanical performance requirements stipulated in the standards.

（3）Strength grade: Tensile strength 120,000 psi (approximately 827 MPa).

（4）Toughness advantage: Compared to Grade 8, it has a higher elongation rate and better shear force-bearing capacity.

（5）Flexibility: The SAE J429 standard does not specify a particular alloy grade. It allows the use of various materials such as 1038, 1040, 35K, 40Cr, etc., as long as the chemical composition and mechanical properties meet the requirements.

（6）Applicable specifications: Diameter range from 1/4" to 1-1/2". For diameters beyond this range, please refer to alternative standards such as ASTM A449.

Material composition

Grade 5 square head bolt is made of medium carbon steel and undergoes quenching and tempering processes, achieving the optimal balance of strength and toughness. The contents of each element are as follows：

Grade Comparison

Grade 5 square head bolt are classified as medium-high strength grade. They achieve an ideal balance between strength, toughness and cost. Compared to Grade 2, they offer higher strength; while compared to Grade 8, they possess better ductility and shear force-bearing capacity, making them suitable for most medium and heavy industrial applications. To give you a clearer understanding, you can refer to the following table content.

Key Advantage

（1）Medium-high strength performance: The tensile strength of the Grade 5 square head bolt reaches 120,000 psi, capable of withstanding medium to heavy loads, which is 62% stronger than Grade 2 strength.

（2）Excellent shear resistance: Compared to Grade 8, it can be adjusted to a different form, making it more suitable for applications requiring shear force.

（3）Adaptability to harsh environments: The square head design can still function effectively in harsh working conditions such as oil stains, mud, and limited visibility.

（4）Installation is convenient: Ordinary open-end wrenches, adjustable wrenches, and star wrenches can all be used for operation, without the need for special tools.

（5）High cost-effectiveness: Achieve the optimal balance between strength and cost between Grade 2 and Grade 8

（6）Widely applicable across industries: covering mining, railways, agriculture, petrochemicals, steel structures and other major industrial sectors