All BUMAX bolts are made with the best possible European steel, and are strain hardened and thread rolled to enhance fatigue resistance.
Superior fatigue resistance
BUMAX fasteners have superior fatigue resistance compared with standard products. Fatigue fracture often begins with a stress concentration in inclusions, slags or surface defects. Our high quality raw materials made with the best metallurgical processes, together with good surface properties, high strength and our rigid quality control guarantees excellent fatigue strength.
Rolled threads are always better than cut threads as the work hardening causes the material to plastically flow without disruption. The compressive stresses that build up during rolling will also increase fatigue resistance.
Extensive fatigue testing of BUMAX® 88 shows superior fatigue resistance compared with standard A4-80 due to the higher yield strength, lower inclusion content and better surface properties. Even better fatigue resistance can be achieved by using BUMAX® Duplex grades, which is often the best choice for very fatigue demanding applications. BUMAX® Duplex can substitute precipitation hardenable grades, carbon steels and other stainless steels.
Contact your local BUMAX sales representative for more information about fatigue resistance and S-N curves.