Keyword: «microstructure»

The article presents the results of a study on multi-pass welded joints made at subzero and ambient air temperatures. Experimental multi-pass welding of low-alloy bridge steel 10HSND (Grade 3) was performed using WN 62U electrodes with registration of the welding thermal cycles. The research results confirm the possibility of producing high-quality welded joints in 10HSND steel under subzero temperature conditions without significant degradation of its performance characteristics.

The article presents the results of studies on the microstructure and mechanical properties of weld metal modified with a natural concentrate of rare-earth elements from the Tomtor rare-metal deposit. It is shown that the structural changes that occur when a complex modifier is added into the charge of coated high-strength ANP-2 type E70 electrodes lead to a 15% increase in the impact toughness of the weld metal at positive test temperatures, and a 50% increase in the test range from –40 to –60 °C.

Drilling of new fields is associated with certain difficulties, mainly the harsh climatic conditions of the Arctic and ultra-long wells. These conditions have a negative impact on traditional steel drill pipes because steel has a cold-fracture threshold and low specific strength. The effect of the scale factor on the fatigue properties and fracture mechanisms of drill pipes made of aluminum alloys D16T and 1953T1 and steel of strength group G-105 has been experimentally investigated. The values of the endurance limit during multi-cycle testing of samples and the fatigue life of drill pipes during full-scale field tests for materials have been determined. A significant reduction in the fatigue characteristics of materials during field tests has been established. It is shown that drill pipes made of aluminum alloys meet the requirements for pipes made of steel of strength group G-105 according to API RP 7G and have a significant advantage in specific characteristics compared with steel pipes, which is especially important during development and drilling in the Arctic regions.