(4mark)Small upset bolt(Coarse Steel Zinc plated(Silver) 10 X 25 Pitch 1.5

In upset forging, the head is cold-formed into a hexagonal or square shape, and there is usually an indentation on the top surface of the head. While it resembles a hex bolt, it belongs to the machine screw family because it has a cross recess.
There are also upset hex bolts without a cross recess, which are classified as hex bolts. Standard hex bolts are made using a process called trimming, where a circular head is first formed and then passed through a die with a hexagonal cavity to shape it.
With upset forging, the corners are rounded and smooth, whereas with trimming, the corners are sharp and angular.

≪※1≫ You can view the manufacturing processes of various manufacturers by searching for "trimmer screw" or "upset screw" on video sharing sites.
≪※2≫ For explanations of the "4 mark" and similar markings, please refer to the bottom of the page.

This is a highly versatile machine screw that can be driven with multiple types of tools. It combines a variety of features — including a hexagonal head with a cross recess and a somewhat softer appearance compared to a hex bolt — making it an interesting choice even for decorative purposes.
Please note, however, that while it resembles a hex bolt in shape, it does not have the same strength as a hex bolt.
Upset Machine Screw Encyclopedia

• (4 Mark) Small upset bolt Coarse pitch
• Nominal diameter (d) M10
• Pitch (p) 1.5
• Length under head (ℓ) 25.0
• Width across flats (s) Nominal 14.0 Tolerance 0,-0.25
• Width across corners (e) Reference 15.51
• Head height (k) Nominal 7.0 Tolerance ±0.2