STABILITY OF THE AUSTENITE AT VARIOUS TEMPERATURES AND MECHANICAL PROPERTIES HOT-ROLLED 40X
In the automotive and many other industries widely used high-strength bolted connections, which are one of the most popular types of machinery parts. The paper studies the strength and plastic properties of the original hot-rolled steel for cold forming metal wares and studied the stability of austenite steel 40X in a soaking bath of saltpeter in the temperature range from 370 to 550 ºC. The residence time of hire in saltpeter bath should be slightly higher since the end of sorbitol conversion. The low bath temperature (below 350 °C) can contribute to the formation of hard and brittle upper bainite structure; heat bath of saltpeter (670 °C above) may lead to a decrease in the strength characteristics of products (formed perlite). Analysis of the products of austenite transformation, the resulting isothermal transformation at different temperatures in the saltpeter bath, shows that in the temperature 630 °C...420 °C obtained eutectoid structure type, the more dispersion, the lower the transformation temperature. This method of cooling at different temperatures saltpeter bath investigated for calibrated rolled with optimum mechanical properties, in full accordance with the required class strength bolting products.