Improving the technology used to make steel for side members

Conclusions

Statistical methods were used to study the effect of the mass content of different chemical elements on the level of the mechanical properties of normalized universal plates of steel 20GYuT.

Multiple correlation equations were obtained and can be used to predict the strength and ductility characteristics of rolled products of steel 20GYuT with a probability of 0.85 in relation to the mass contents of carbon, manganese, and titanium determined from chemical analysis of ladle samples.

A study was made of the feasibility of making side-member steel with a mass content of manganese below the level specified by the standard TU14-1-4632-93 (1.0–1.14%).

It was established that normalization of heats with a mass content of manganese of 1.0–1.14% produces the specified set of mechanical and service properties as long as the mass content of carbon in the steel is at least 0.19%.

To ensure that the required set of mechanical and service properties is obtained, it is recommended that steel 20GYuT be made with a carbon content of 0.19–0.23%, a manganese content of 1.0–1.3%, and a titanium content of 0.10–0.14%.

The recommended chemical composition of steel 20GYuT and the heat-treatment regimes that have been developed for rolled plates of this steel will make it possible to do the following:

• ⊙ attain the required level of quality of the steel plates mainly with the use of a single heat treatment—normalization;

• ⊙ decrease the actual consumption coefficient;

• ⊙ substantially reduce the production cost of the steel through the conservation of ferromanganese and a reduction in the costs incurred by multi-stage heat treatment.