Thru Hardened Flat Washers

  • Industrial Thru Hardened Flat Washers

Rettig’s is your go-to supplier of wholesale thru hardened flat washers and other high-quality industrial supplies.  Our knowledgeable staff is technically trained and able to work with your complex supply list to find the best solution for your industrial application.  We have the in-stock inventory to stock any jobsite with bulk orders at wholesale prices, from fasteners to valves and beyond.  

Thru Hardened Flat Washers – Engineered for Strength, Built for Performance

When your fastening system demands maximum strength and load retention, thru hardened flat washers are the trusted solution. These washers are specifically heat-treated to enhance hardness, strength, and wear resistance, making them essential in high-stress applications where standard washers simply won’t hold up.

Ideal for use with Grade 5, Grade 8, and structural bolts, thru hardened flat washers maintain their shape and integrity under extreme compression, vibration, or torque. You’ll commonly find them in construction, heavy machinery, automotive, steel fabrication, and structural steel assemblies, where durability is a must.

What sets these washers apart is the thru hardening process, which ensures the entire washer—not just the surface—is uniformly hardened. This allows for better clamping force retention and prevents the washer from flattening or distorting under load. They also reduce galling and fretting between the fastener and the surface material, improving the longevity of both.

Specifications & Features:

  • Material: Typically made from medium carbon or alloy steel

  • Hardening Process: Heat-treated to achieve consistent hardness throughout

  • Sizes Available: Standard diameters from 1/4" up to 1-1/2"+

  • Finishes: Available in plain, zinc plated, and hot-dip galvanized for corrosion resistance

  • Compatible With: Grade 5, Grade 8, and ASTM A325/A490 structural bolts

  • Standards: Often conform to ASME B18.22.1 and ASTM F436 (for structural applications)

Whether you're anchoring steel beams or assembling heavy-duty equipment, thru hardened flat washers ensure the connection stays tight, strong, and safe over time.

Need help finding the right washer for your load-bearing project? Our fastener experts are here to guide you—reach out today for expert recommendations!