A Study on Cracking Characteristics of Ti-containing AISI 436 Ferritic Stainless Steels

The microstructure and mechanical properties characteristics in AISI 436 weld metal were investigated for different ranges of chemical composition of stabilization element Ti Three new filler wires were designed for flux cored arc welding (FCAW) process, and the Ti contents and solidification path of each of the weld metals was changed. Each specimen of AISI 436 transformed to fully ferrite or ferrite and martensite. Ti suppressed the formation of martensite and had a grain refinement effect. The tensile strength varied according to the content of additional Ti. The effects were negligible when 0.5 wt% Ti was added, but the tensile strength increased by 41 MPa with the addition of 0.8 wt% Ti. When the amount of added Ti was greater than 0.5%, some Ti dissolved. The increase in tensile strength is attributed to the remaining undissolved Ti. Cracking occurred in the specimens contained added Ti. Fracture monograph observed the Transgranular Cleavage Fracture that is a commonly occurring phenomenon in Mediumchromium Ferritic stainless steel. This crack may be influenced by stabilization elements and cooling speed.