Localized Induction Heating For Residual Stress Optimization

Abstract

An apparatus for the heat-treating of a heat-hardenable steel cruciform article having a weld seam includes a heating element to heat the weld seam to a point that an austenitic transformation occurs, and a quenching chamber to cool the weld seam, causing the formation of Martensite and an associated expansion. The quenching is rapid since slow quenching may allow a crystalline phase other than martensite to form. The apparatus may comprise rollers operable to convey the welded cruciform article through the apparatus at a speed such that the weld seam is subjected to heating for a predetermined heat time sufficient to cause a formation of martensite there within, and such that the heated portion reaches the quenching chamber and is quenched to create a substantial amount of martensite, e.g., an amount sufficient to cause expansion of the part.

1 - 15 . (canceled) 
     
     
         16 . A heat-treated steel cruciform article comprising first and second steel plates joined by a steel weld seam, wherein the steel weld seam contains residual compressive stress. 
     
     
         17 . The heat-treated steel cruciform article according to  claim 16 , wherein the steel weld seam comprises an amount of martensite substantially greater than that of annealed steel of the same type. 
     
     
         18 . The heat-treated steel cruciform article according to  claim 16 , wherein the steel weld seam comprises an amount of martensite substantially greater than that of the first and second steel plates. 
     
     
         19 . The heat-treated steel cruciform article according to  claim 16 , wherein the steel weld seam comprises low alloy low carbon steel. 
     
     
         20 . The heat-treated steel cruciform article according to  claim 16 , wherein the cruciform article is of a cruciform cross-section.