High strength forged steel e.g. for crankshafts - is given improved strength by alloying with a small amt. of nitrogen

摘要

Heavily stresses steel forgins are given improved strength by alloying a steel contg. 0.25-0.60% C, 0.30-0.70% Si and pref. 0.10-0.35% Cr, 0.50-1.20% mn, with 0.0120-0.035% N (0.0140-0.0230%N), and limiting the content of elements with a high N affinity to pref. only trace amts. The non-heat treated forging is suitable for crank-shafts. Method gives a high strength steel without using a costly alloying element such as V or Nb in large amts.