Defects of low-carbon engineering steels 18Kh2N4MA, 25Kh2N4MA, 25G2S2N2MA reducing the operational durability of the parts were studied. The most common defects of the metallurgical processing are: non-metallic inclusions, microstructure banding, internal cracks and pores. It has been established that the inclusion of titanium carbonitride significantly reduces the operational durability of heavily loaded parts.