PRODUCTION OF SPRING STEEL EXCELLENT IN HARDENABILITY AND WARM SETTLING RESISTANCE

摘要

PURPOSE:To obtain a spring steel capable of providing sufficient as-quenched hardness at low temp. in a short time and also excellent in warm settling resistance which is an important property required of the spring used in a high-temp. atmosphere by specifying the components, composition and manufacturing conditions of the steel, respectively. CONSTITUTION:A steel which has a composition containing, by weight, 0.4-0.8%C, 0.5-2.5% Si, 0.3-2.0% Mn, 0.1-1.5% Cr, and 0.1-1.5% Mo and satisfying the condition of -7=4XSi(%)-10XCr(%)=5 is hot-rolled, annealed, cold-rolled at 10-80% cold rolling rate, and annealed at 550-730 deg.C. Then, the resulting annealed material having =2/mum average carbide grain size is subjected to quench-and-temper. This steel can further contain V and/or Nb by 0.05-0.5wt.%. Moreover, it is preferable to control Al content to =0.020wt.%.