Extensometer for measuring yield strength of pipeline steel plate-shaped tensile sample

The utility model discloses an extensometer for measuring the yield strength of a pipeline steel plate-shaped tensile sample, one side of an extensometer main body is provided with a fastening mechanism, the fastening mechanism comprises a connecting plate, the middle of the connecting plate is symmetrically and rotatably connected with pulleys, and the pulleys are symmetrically and rotatably connected with the connecting plate. Limiting rails are fixedly installed at the top of the connecting plate and located on the two sides of the pulley, movable plates are slidably connected to the inner walls of the tops of the two limiting rails, racks are fixedly installed on the two sides of the outer walls of the movable plates, and sliding rods are symmetrically slidably connected to the inner walls, away from the limiting rails, of the movable plates. The sliding rods on the two sides penetrate through the movable plate and are fixedly provided with pressing plates, when the tested steel is separated from the clam