Two-piece blind fastener

A blind fastener comprising:

• a single piece bolt including:
• a shaft;
• a bolt head extending radially outward from the shaft, an end of the shaft opposite the bolt head defining external threads;
• and
• a lug, the bolt head being disposed between the shaft and the lug, the lug including a first tool engagement portion and a first frangible portion that frangibly couples the first tool engagement portion to the bolt head;
• and
• a single piece nut including:
• a sleeve including a central bore configured to receive the shaft, the sleeve defining internal threads engaged with the external threads;
• a nut head extending radially outward from the sleeve and defining a recess configured to receive the bolt head, an outer surface of the bolt head being flush or recessed relative to an outer surface of the nut head when the bolt head is received in the recess;
• a handling member, the nut head being axially between the handling member and the sleeve, the handling member including a second tool engagement portion and a second frangible portion, the second tool engagement portion being configured to surround at least a portion of the lug, the second frangible portion frangibly coupling the second tool engagement portion to the nut head, and
• a seal member in contact with the shaft and the sleeve to form a seal therebetween,
• wherein the sleeve includes a first zone proximate to the nut head, a second zone at the internal threads, and a ductile zone between the first and second zones, the ductile zone being more ductile than the first or second zones, and
• wherein the ductile zone is a variable annealed zone that has a hardness that varies along the entire length of the ductile zone, wherein a location of minimum hardness is located approximately half-way between the first zone and the second zone and the hardness of the sleeve in the ductile zone increases with increased axial distance from the location of minimum hardness until reaching the first zone and second zone.

A blind fastener for connecting a plurality of panels, comprising:

• a bolt including a shaft, a bolt head, and a lug, the bolt head being disposed between the shaft and the lug and extending radially outward from the shaft, an end of the shaft opposite the bolt head defining external threads, the lug including a first tool engagement portion and a first frangible portion that frangibly couples the lug to the bolt head;
• and
• a nut including a sleeve, a nut head, and a handling member, the sleeve including a central bore configured to receive the shaft and defining internal threads configured to mate with the external threads, the nut head being disposed between the handling member and the sleeve, the nut head extending radially outward from the sleeve and defining a recess configured to receive the bolt head, the handling member being configured to surround at least a portion of the lug, the handling member including a second frangible portion and a second tool engagement portion, the second frangible portion frangibly coupling the second tool engagement portion to the nut head;
• and
• a seal member in contact with the shaft and the sleeve to form a seal therebetween.