The fourth chapter of How Steel Was Tempered mainly described the training and growth process of the protagonist, Pavel Kochagin, in the steel industry of the Soviet Union. This chapter was originally written in 1924, and it recounted his experiences working in a steel factory in Ukraine called Kyiv. In the factory, Kochagin encountered some difficulties and challenges, but through continuous efforts and learning, he gradually grew into an excellent steel worker and leader. In this chapter, Kochagin also met some important people, including his colleague and good friend Boris Pajitnov, as well as his superior and mentor Vladimir Ilyich Lenin. They had experienced the historical transformation of the Soviet steel industry and witnessed the development and growth of the Soviet society. In addition, this chapter also discussed Kochagin's personal growth and outlook on life, including his attitude towards work, his views on family and love, as well as his thoughts and understanding of Communism and Society. All of these laid the foundation for the growth and life experiences of Kochagin in the subsequent chapters.