Rectangular test piece head coated with protective coating

The utility model discloses a rectangular test piece head coated with a protective coating, which belongs to the technical field of test piece heads, and comprises a test piece head body, a first clamping block is arranged in the test piece head body, the outer surface of the first clamping block is mutually clamped with the inner wall of a first clamping groove, the first clamping block is mutually clamped with a connecting block through the first clamping groove, and the connecting block is connected with the test piece head body. The lower surface of the connecting block is fixedly connected with the upper surface of a chuck, and a plurality of second clamping grooves are formed in the outer surface of the chuck. According to the rectangular test piece head coated with the protective coating, by arranging the rotating disc, the first clamping block, the first clamping groove, the chuck, the second clamping block and the second clamping groove, the connection tightness of the test piece head body and the mo