On November 23, 2022, with the last vehicle of non quenched and tempered steel round steel loaded and delivered, HNXG Steel Group completed the first batch delivery of non quenched and tempered steel for automobile forged crankshaft of Huizhou Nippon Steel Co., Ltd. This batch of non quenched and tempered steel bars will be used to manufacture GAC Mitsubishi brand new Outlander engine crankshaft.
This marks that HNXG's high-end non quenched and tempered steel bars have entered the mainstream automotive manufacturers' supply chain.
Non quenched and tempered steel is a kind of steel with excellent performance, high efficiency and energy saving. It does not need heat treatment, and its mechanical properties in hot rolling state reach or approach those of quenched and tempered steel.
Compared with quenched and tempered steel, non quenched and tempered steel has shorter production cycle, lower energy consumption and better cost performance because it can reduce processes. It is called "green steel" and is mostly used in important parts such as automobile crankshafts and connecting rods.
Crankshaft is one of the core components of automobile engine. Automobile engine manufacturers have very high requirements for the quality of non quenched and tempered steel used for crankshafts. It is not only required that the internal structure and element distribution of finished round steel are uniform, the shape of inclusions is excellent, but also that the surface and internal flaw detection are free of defects.
However, the content of sulfur and nitrogen in non quenched and tempered steel is high, resulting in poor castability in the production process. Ordinary molten steel can be continuously casted for about 15 heats, while non quenched and tempered molten steel can only be continuously casted for about 3 heats, and the surface quality control is difficult.
HNXG not only ensures the surface quality, but also gradually improves the production efficiency by optimizing the refining slag making deoxidation, calcium sulfide treatment process, improving the inclusion morphology, adjusting the nitrogen increasing process and other measures. At present, 4 to 5 heats of non quenched and tempered steel can be continuously cast.
HNXG's non quenched and tempered steel for crankshaft has passed the certification of Mitsubishi Motors, Geely Motors, and Pan Asia Motors (General Motors China) main engine plants. Among them, GAC Mitsubishi and Geely Motors have entered the stage of batch supply, both of which are produced by high-quality small and medium-sized bar lines, and nearly 1000 tons have been supplied;
The certification of North American GM and Thailand Toyota has also been passed, entering the product trial stage.