Patent ID: 6365866
Filing Date: 2002-04-02
Classification: B23K

Abstract:
A method for welding hardenable steel, said method comprising:preheating said steel for an energy exposure period &tgr;S greater than or equal to 0.3 s and less than or equal to 20 s, such that a heating depth is between 0.3 and 5.0 times a welding seam depth &tgr;S, and a peak temperature Tmax greater than or equal to 620Â° K. and less than or equal to TZâˆ’30Â° K., where TZ corresponds to a temperature of a preceding annealing treatment when said steel is in a hardened and annealed initial state, and corresponds to a temperature at which spheroidizing for cementite perceptibly being in said steel between 1 s and 100 s when said steel is in a ferritic-pearlitic initial state; permitting said steel to cool for a time &tgr;A greater than or equal to 0.01 s and less than or equal to 30 s, such that said heating depth is between 1.0 weld seam depth tS and 5 weld seam depth tS, welding said steel; quenching a welding zone and a heat affected zone of said steel for a time t8/5, which is greater than or equal to &tgr;K, where &tgr;K corresponds to a quenching time in which a proportion of ferrite, pearlite, and bainite in said welding and heat affected zone is at least 70% and a hardness of said welding and heating zones are less than 350 VH0.05; and increasing a width of and a relative depth of a preheating zone of said steel until cooling takes place so slowly that &tgr;K is reached or exceeded.