POSTER REFERENCE: ICF10039OR EFFECT OF CRACK ORIENTATION AND WELDING PROCESS ON J-INTRGRAL VALUES Qingfen Li, Li Li, Shengshan Yang, Shanglin Yang and Shu-tong Yin College of Mechanical & Electrical Engineering Harbin Engineering University, Harbin 150001, China ABSTRACT A series of tests was performed with SENB specimens on a Titanium alloy. Results of seven groups of specimens show that the j-integral values of L-T direction specimens are much higher than those of L-S ones. The J-integral values of rolled ring are as : J C-R >J C-L >JL-R. And that the J values of welded joint and HAZ are obviously smaller than those of the base metal. It signifies that the welding process can result in a reduced toughness of Ti-alloy and the effect of crack orientation on toughness value is not negligible for engineering applications. KEYWORDS: J-integral, Ti-alloy, crack orientation, welding process INTRODUCTION J-integral meathd plays a significant role in elastoplastic fracture mechanics. As an important fracture characteristic parameter, it is already well developed and extensively used in engineering prictice1. The heat affact zone (HAZ) is in many cases considered to be the most critical part of a welded structure with regard to unstable fracture. It is evident that the designers need to know the fracture toughness of welded joint, HAZ and parent plate as affected by the heat of welding, since the welded metal, the HAZ and the parent material normally have different fracture toughness. Studying the effect of welding process on J-integral value for Ti-alloy has been proved to be very useful for engineering applications. An experimental investigation is therefore carried out in this paper. Besides, the effect of crack orientation on J value is also investigated, because in some materials, such as forging, extrusions or plates, crack orientation can have an important bearing on fracture toughness measured. EXPRIMENTAL PROCEDURE material and Specimens A chinese Ti-alloy plate and rolled ring were used. Their chemical composition is given in Table 1, and the mechanical
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