In modern mechanical engineering, the choice of material for the manufacture of load-bearing elements and the body of a semi-trailer is a determining factor affecting its load capacity, curb weight and overall service life. Russian plants, such as Tonar, Mechanical Plant Sotrans near St. Petersburg, Grunwald, Bonum and NEFAZ, have gone through a serious path of technological evolution in recent years, abandoning the use of exclusively heavy standard rolled metal in favor of advanced steel alloys. Today, production of domestic trailers uses a differentiated approach, in which every design detail - from frame side members to the sides of the dump body - is made from a strictly defined grade of steel, providing an ideal balance between strength, ductility and specific gravity.
Classic structural basis
The basis for most elements of frames and bodies of budget series of domestic semi-trailers is traditionally low-alloy structural steel grade 09G2S (and its European analogue S355). This alloy has gained enormous popularity due to its excellent weldability, high mechanical strength and, what is especially important for Russian conditions, outstanding cold resistance, allowing the metal to maintain impact strength at extreme temperatures up to $-70 \text{°C}$. 09G2S steel is widely used in the production of chassis elements, sides of tented semi-trailers and dump truck frames, since it can withstand static loads well and can be repaired using standard welding equipment in a normal vehicle fleet.
High-strength steels for frame structures
For the manufacture of load-bearing frames for new-generation mainline semi-trailers, where it is critical to reduce the dead weight of the chassis to increase the payload capacity, Russian manufacturers actively use high-strength low-alloy steel (HSLA) of the S420 and S700 classes (for example, imported analogues such as Domex or domestic high-strength grades).
The use of S700 class steel when molding the frame side members makes it possible to reduce the thickness of the metal elements without losing structural strength, due to which the dead weight of the curtainsider semi-trailer is reduced by several hundred kilograms.
The high yield strength of such steels ensures that the semi-trailer frame will elastically absorb road irregularities under full load, completely restoring its original geometry after passing through difficult sections of the road.
Wear-resistant alloys for severe conditions
In the production of dump bodies intended for transportation of rocks, crushed stone, sand and other highly abrasive materials
