Mild steel coach bolts are ok for hanging the door on your chicken shed. These are better https://www.ebay.co.uk/itm/M6-FLANGED-HEXAGON-BOLTS-8-8-HIGH-TENSILE-PLATED-STEEL-FLANGE-HEX-HEAD-SCREWS/183187937882?hash=item2aa6da1a5a:m:mNDVZFkv-anlYqxgOa2thaw Cap head sockets 8.8 grade would also do the job.
Fatigue shouldn't be a problem. The bolts aren't subject to any cyclic stress, they're only under tension. https://www.engineeringtoolbox.com/steel-endurance-limit-d_1781.html
Fatigue shouldn't be a problem. The bolts aren't subject to any cyclic stress, they're only under tension. https://www.engineeringtoolbox.com/steel-endurance-limit-d_1781.html