Square Head Black Oxide Lag Screw

Square Head Black Oxide Lag Screw with China Xiaoguo® are a type of heavy-duty self-tapping fastener with a square head, a threaded rod section with coarse teeth, and a conical tip at the tail.The dimensions of the opposite sides of the square-shaped head are in accordance with the standard. It can be operated with an open wrench, a movable wrench or a special square socket.The thread adopts a partial thread design, with a wide pitch and deep tooth profile. The tail angle is approximately 30° - 45°.

During installation, pre-drilled guiding holes need to be made on the wood. The mechanical interlocking between the Square Head Black Oxide Lag Screw threads and the wood fibers generates high uplift and shear resistance.The material is usually carbon steel or stainless steel. It is mainly used in wood structure buildings, railway sleepers, heavy wooden equipment bases, etc., in situations where high load-bearing capacity is required and the head should not slip easily.

Material Introduction

Regarding the material introduction of Square Head Black Oxide Lag Screw, we will elaborate on it from the following aspects.

1.The most commonly used material is carbon steel, with the grade 10B21 or Q235. Grade 10B21 has good hardenability and is suitable for making high-strength 8.8 grade products; Square Head Black Oxide Lag Screw made of Q235 material are suitable for the 4.8 standard and are commonly used in ordinary indoor wooden structures.

If carbon steel is used, surface treatment must be carried out; otherwise, it will rust.For indoor use, electro-galvanized coating is recommended; for outdoor use, hot-galvanized or Dacromet coating can be selected.

Carbon steel is relatively inexpensive and has high strength, making it the preferred choice for most customers.

2.Stainless steel

If used in humid environments or outdoors, choosing stainless steel is more convenient.We offer two types: 304 and 316.304 is suitable for balcony flower racks, bathroom wooden frames, and kitchen wooden products. 316 is resistant to seawater corrosion and is specifically used for coastal wooden walkways, docks, and around swimming pools.

Stainless steel does not require surface treatment. It resists rust due to the material itself, and its surface appears silvery white. The strength is approximately 700 MPa, slightly lower than the 8.8 grade of carbon steel, but there is no difference in usage.

3.Special custom-made material

In addition to conventional carbon steel and stainless steel, we also offer customization services for other materials such as brass, aluminum alloy, and titanium alloy. If you have any special requirements for surface treatment, we can discuss it.

4.Select materials based on the usage environment

Don't know how to choose the material? Consider the actual usage scenarios:

Indoor drying: Carbon steel 4.8 grade + electro-galvanizing

Indoor humidity: Stainless steel 304

General outdoor: Hot-dip galvanized carbon steel or stainless steel 304

Coastal outdoor: Must use stainless steel 316