METHOD OF HEAT TREATING NON-ALLOYED OR LOW-ALLOYED BAININITIC HARDENED STEELS OF LOW MARTENSITE TRANSFORMATION POINT

摘要

The invention provides a steel (or a steel article such as a fastener for use in an explosive-powered fastener- driving tool) which is both tough and strong, economically, and comprises: 0.50 to 1.00% carbon 0.10 to 1.50% silicon 0.25 to 1.50% manganese up to 0.045% phosphorus up to 0.045% sulphur 0.20 to 0.90% molybdenum and/or 0.20 to 2.00% chromium, the remainder being iron, possible slight-alloying elements and impurities, having been subjected to a bainite hardening treatment in the region of or at temperatures above the martensite point in the range 0 to 100 DEG C above said point, until a maximum transformation of 85% has been achieved. The invention provides, also, a corresponding method.