Abstract
Nowadays, in various industries, in particular in nuclear energy, to determine the fracture toughness, along with standard tests of compact specimens, which are quite expensive and complex, methods are developed to determine these characteristics by impact tests of Charpy specimens using different correlations between Charpy impact fracture energy (CVN) and critical stress intensity factor (J-integral). The paper analyzes correlation and analytical methods, the authors of which consider them universal for a certain class of steels. Correlation methods are divided into one-stage and two-stage. One-stage methods allow to obtain the value of the critical stress intensity factor by the known fracture energy. Two-stage methods in the first stage offer the calculation of the dynamic critical stress intensity factor, in the second the temperature shift and obtaining a static critical stress intensity factor. Analytical methods according to the іmpact fracture diagram of the specimen allow to construct a J-R curve and calculate the value of the J-integral. A series of fracture tests of CT specimens made of heat-resistant steel 22K was carried out, the reference temperature T0 was determined according to the single-temperature method of the ASTM-1921 standard and the Master curve was constructed. A series of standard Charpy specimens impact tests in the temperature range -50…+100°С was performed using an instrumented drop-weight impact testing machine equipped with a high-speed registration system. According to the results of Charpy specimens impact tests, the fracture toughness were determined using different methods. It is established that both analytical and correlation methods cannot be universal and can be used to determine the fracture toughness of 22K steel. Therefore, a new exponential correlation was proposed between the fracture energy of the Charpy specimens and the critical stress intensity factor for heat-resistant steel 22K.
Highlights
complex, methods are developed to determine these characteristics by impact tests of Charpy specimens using different correlations
Correlation methods are divided into one-stage and two-stage
One-stage methods allow to obtain the value of the critical stress intensity factor by the known fracture energy
Summary
Випробування компактних зразків СТ-0,5 зі сталі 22К проводились, згідно методики стандарту. 25oС проводились випробування на визначення силової характеристики KIC. 25oС≤Т≤10oС проводились випробування на визначення енергетичної характеристики тріщиностійкості JIC. Ударні випробування проводились на інструментованому вертикальному копрі [12], обладнаному високошвидкісною багатоканальною системою реєстрації зусиль та деформацій (частота дискретизації 20 МГц), а також системою нагріву та охолодження зразків у широкому діапазоні температур [13]. +100oС при швидкості удару V0= 5 м/с [14,15]. Зразки Шарпі та компактні зразки вирізались з елементу трубопроводу зі сталі 22К в одному напрямку
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
