Bolt with expansion shank DIN 2510L-steel 1.7709 M20x150 mm

Grade 1.7709 is a heat-resistant structural steel that is listed in DIN 17240. Steels that demonstrate good mechanical properties over a longer period of time are referred to as heat-resistant. The focus is particularly on the elongation strength, the creep strength and the relaxation resistance in the temperature range up to 540 °C.

Steel is an iron-carbon alloy with a maximum carbon content of 2% by mass. The steels achieve their intended physical and mechanical properties through various hardening, annealing and tempering processes. It is also possible to harden the edge zone by surface hardening, case hardening or nitriding. Well-known steel grades are structural steels, free-machining steels, case-hardening steels, nitriding steels, tempering steels, tool steels and stainless steels.

The term plain indicates a completely untreated, merely oiled, smooth surface for all DIN and ISO screws such as wood screws, hexagon head screws, threaded rods, nuts and many types of washers.