AWS-G2 4-G2 4M pdf free download

AWS-G2 4-G2 4M pdf free download.Guide for the Fusion Welding of Titanium and Titanium Alloys.
alpha-beta grades or alloys. Most of the alpha-beta alloys are considered heat treatable with a wide range of possible properties. Their strength levels are medium to high hut their creep strength is not as good as most alpha alloys. Their forming qualities are acceptable hut generally exhibit a significant amount of spring-hack.
alpha stabilizer. An alloying element that dissolves preferentially in the alpha phase and raises the alpha- beta transformation temperature. Typical alpha stabilizers, such as aluminum. oxygen, tin, and nitrogen. increase the temperature at which the alpha phase is stable.
beta grades or alloys. The beta or near-beta alloys have a high percentage of beta-stabilizing elements in this group of titanium alloys, resulting in a microstructure that is metastable beta (a nonequilibrium state persisting for some period of time) after solution annealing. Extensive strengthening can occur by the precipitation of alpha during aging. Heat-treating is common and care should he taken in the welding of these alloys. These grades promote higher density, increased response to heat treatment, higher short- term strength. increased strain rate sensitivity, and improved fabricahility especially in the solution treated condition.
beta stabilizer. An alloying element that dissolves preferentially in the beta phase and lowers the alpha-beta to beta transformation temperature. Typical beta stabilizers include vanadium, molybdenum, manganese. iron, nickel, copper, and silicon. Beta stabilizers can be divided into two categories according to their constitut ional behavior with titanium: heta-isomorphous elements and beta-eutectoid elements.
beta phase. The high-temperature allotrope of titanium with a body-centered cubic (BCC) crystal structure that occurs above the beta transus.
beta transus. The minimum temperature above which equilibrium alpha does not exist.
body -centered cubic (8CC). A unit cell that consists of atoms arranged at cube corners with one atom at the center of the cube. This is the typical crystalline structure of the beta phase of titanium.
commercially pure (CP). The mechanical properties of CP titanium are influenced by small additions of oxygen and iron. By careful control of these additions, the various grades of commercially pure titanium are produced to give properties suited to different applications.
To prevent contamination from air, complete inert gas shielding of the face and root of the weld is required. Similarly, hot titanium reacts with and is einbrittled by most materials, including organic and inorganic cornpounds and some metals. And in the case of welding titanium to other refractory/reactive metals, detrimental alloy compositions or compounds may form. Hence, the parts to be welded must be meticulously cleaned of mill scale, oil and grease from machining operations, dust, dirt. moisture. and other potential contaminants.
The precautions necessary to maintain the required levels of cleanliness and shielding for successful titanium welding are discussed throughout this document. Many of the precautions may at first seem costly or unnecessary. especially for organizations that deal with titanium on an infrequent basis. However, it is important to remember that contamination of the weld has the potential to significantly increase the overall welding Costs through the need for excessive weld repair. In this respect, the higher initial cost of establishing the proper procedures for titanium welding will result in significant savings over the production run through reduced scrap and rework and timely delivery of high-quality products.
4.1 Oxygen, Nitrogen, Carbon, Iron. an(l Titaniuni. A basic understanding of how titanium interacts with oxygen. nitrogen, carbon, and iron will help in understanding the importance of cleanliness and inert shielding in successful titanium welding.AWS-G2 4-G2 4M pdf download.