We commonly use wire rod steel grades for manufacturing screws and bolts, mainly based on the strength grade and usage environment of the screws. The common types are as follows,Selection of carbon steel materials: 

Mild steel

Q195,Q215,Q235,1008, 1015, 1018, 1022: They belong to ordinary carbon structural steel with low strength and are generally used to manufacture screws below 4.8 grade. Their main advantages include low price, good plasticity, easy processing, and suitability for manufacturing screws with low strength requirements, such as Drywall screws, wood screws, pan head tapping screws, etc.

Medium carbon steel

35 #, 45 #: Medium carbon high-quality structural steel, which can improve strength after heat treatment, is commonly used to manufacture medium strength screws, and can generally produce 8.8 grade screws and bolts. It is widely used in mechanical, construction and other fields, such as hexagonal bolts,Allen bolt.

Alloy steel

40Cr,SCM435(AISI 4135)20Cr,20CrMnTi, After quenching and tempering treatment, it has high strength and toughness, suitable for manufacturing high-strength screws and can be used to make bolts of grade 10.9 or above, such as key connection parts in automobiles and mechanical engineering. Common ones include Allen bolts and hexagon socket head bolts.Selection of commonly used stainless steel materials: 

Austenitic stainless steel:

304 (SUS304): Moderately priced, it is the most commonly used material for stainless steel bolts, commonly used in corrosive environments such as electronic devices, household appliances, or ordinary building structures. Its mechanical properties are moderate, with a tensile strength of about 520 megapascals, but it does not support heat treatment strengthening, and its hardness is average

316 (SUS316)/316L: Adding molybdenum element enhances corrosion resistance. Bolts and screws made of 316 are usually used in food machinery or highly corrosive marine environments. Among them, 316L has lower carbon content and better intergranular corrosion resistance after welding

Martensitic stainless steel (such as 410, 420): can be strengthened by heat treatment to increase strength (hardness 35-45HRC), suitable for wear-resistant or moderately corrosive environments, but has weaker corrosion resistance than austenite and should be avoided from long-term exposure to humid environments.Usually used for manufacturing self drilling screws with good penetrability, used for fixing roofs of houses

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Ferritic stainless steel (such as 430): Low cost, suitable for less corrosive scenarios such as temporary building fixation but with lower strength