In Tokyo, Japan, at the "low-carbon technology • System 3R Positive business results report" on Tokyo Steel Technology Development Department, made a presentation about the "scrap automobile parts in highly utilized investigative techniques." 2012-2013 fiscal year, the actual verification of 100% scrap as raw 980-1180MPa grade steel furnace with the same or better and blast furnace production process mechanical properties of materials; fiscal year 2014, was in the car parts on electric steel suitability evaluation and estimation of the effect of improving the environment, and the impact of electric steel elements inherent quality of steel surface were investigated.
 
Effect of electric steel peculiar residual elements on the car-specific quality requirements (surface quality) of
 
In general, electric steel raw material - scrap contains an average of 0.25% -0.30% Cu, 0.10% Ni, 0.15% Cr, 0.03% Mo. When the residual elements in a solid solution state in material, generally does not affect the mechanical properties of the survey 980-1180MPa trial stage furnace material also verified this inference. People often worry embrittlement of Cu. This is a steel surface accompanied by oxidation at high temperatures, the surface layer of Cu concentrated phenomenon, precipitated Cu to infiltrate the liquid state to a crystalline grain boundaries, leading to embrittlement of the material surface. In addition, car paint rust coating usually by chemical way, and when Electrochemistry expensive elements Cu covering the surface of the steel sheet, it is also worried about whether it will impede chemical treatment. Further, since the easily oxidized Fe, and Cu, Ni, etc. easy to be oxidized, Cu, Ni and Fe was concentrated at not oxidized is oxidized unevenness becomes large.
 
Smooth surface and no internal oxidation of the steel surface is the ideal state. By accelerating the phenomenon of Cu-enriched furnace, roughing, finishing the steel surface before the detailed investigation found that not as imagined by large Cu content (0.30%) caused by deterioration of smoothness, and by selecting the appropriate production conditions, also be obtained in the surface condition of equivalent steel blast furnace process manufacturing. It was also found to increase the strength of the case Si added surface roughening caused by the addition of Cu can also be alleviated.
 
In the inner layer with the grain boundaries of the matrix of iron oxide situation observed Cr, Mn denser, which means that the internal ends of these oxide layers thick, it is possible to use means of Cr, Mn, etc. as an internal control of the depth of the oxide layer.
 
When entering the furnace and were not found on the grain boundaries of Cu infiltration when roughing, it is considered that as long as a reasonable set of production conditions, it will not produce Cu embrittlement.
 
Ordinary high-strength rating (370-400MPa) electric furnace steel actually used in the manufacture of automotive parts evaluation and residual elements of the impact evaluation of the basic characteristics of the material
 
Each trial the average Cu content (0.26%) material, the upper limit of the Cu content (0.30%) material, the lower limit of the Cu content (0.20%) EAF steel and blast furnace processes produce low Cu (0.02%) Material four grades of Cu contents of evaluated. The results show that: tensile strength, yield strength is substantially independent of the Cu content level. With the increase of the Cu content, total elongation, ductility, limiting drawing ratio were associated with the blast furnace production process material equivalent, and hole expansion ratio higher than about 50% blast furnace material. Electric furnace steel features --Cu solid solution strengthening, can produce less material than the blast furnace C content and low proportion of pearlite ferrite steel, and exhibits from the coiling temperature stability characteristics.
 
Cu content of 0.30% as the evaluation of TS390MPa steel material, while manufacturability with the actual manufacture of automotive components were evaluated, the evaluation process for selecting the plastic flow requirements are very strict and accompanied by changes in the thickness and extension, while forming in the general context of the most difficult parts stamping, shaping not only the success and produce cracks, defects, shape and size of the metal flow component, part cross-sectional observation was to evaluate internal cracks in both the current production of the blast furnace process with the same material the level of production would not confirm a problem.
 
Future development of automotive steel in electric furnace steel areas
 
Comprehensive business development in fiscal year 2014 and found that: by selecting the appropriate production conditions, even if the Cu content of 0.30%, it will not cause embrittlement risk; when Si is caused due to surface roughness, surface concentration of the phenomenon may also be on its Cu control; in the evaluation of the actual member, scrap of Cu not only not harmful elements, but rather favorable element; through to the use of scrap, reducing steel production process, CO2 emissions, and the current electric furnace steel is gradually satisfied as the car with the overall performance of the steel sheet.
 
The future need to build and solidify even if Cu content of 0.30% can meet the chemical treatment, fatigue characteristics, spot welding and other technical requirements. Currently we are moving forward and auto parts enterprises of material recognition, while the technology-based, auto companies and steel together to seek an extension.