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Hydrocarbon pipelines transporting compressible products like methane or high‐vapor‐pressure (HVP) liquids under supercritical conditions can be susceptible to long‐propagating failures. As the unplanned release of such hydrocarbons can lead to significant pollution and/or the horrific potential of explosion and/or a very large fire, design criteria to preclude such failures were essential to environmental...
This paper reports on the experience with the production of 27/33 mm X80 heavy wall thicknesses, large OD (48”) in ShouqinSteel Co., Ltd. (SQS). Considering the technology capability of the plate mill in SQS, a optimized rollingand cooling process was developed to achieve stable heavy gauge X80 mechanical properties. The importance of the slab reheating process and rolling schedule will...
With the increase of wall thickness of pipeline steel, DWTT fracture toughness has become more and more sensitiveto production process, including alloy design and processing, so it need more tight and more systematic control from the alloy design, reheating, rolling and finally cooling to improve upon DWTT property of heavy gauge X80 strip. In this paper, Through hot simulation and subsequent analysis,...
Aging of microalloyed steel pipe can occur at relatively low temperatures associated with the pipecoating process and/or during long term storage or use. The aging phenomenon is primarily attributed to C diffusion to dislocations and subsequent pinning of these dislocations. Important factors in the aging process include time, temperature, chemical compositionand plastic deformation(arising from the...
This study is focused on the effect of vanadium addition to an API X100 steel. Laboratory heats were melted and control rolled based on a coil plate production process. Compared to non vanadium steel, it was found that 0.06% vanadium added steel had 8 to 14% higher yield and tensile strengths in all directions, while the toughness and ductility were similar for both steels. It is believed that the...
Over the past twenty years, significant advances have been made in the field of microalloying andassociated application, among which one of the most successful application cases is HTP practice for heavy gauge, high strength pipelinesteels. Combined the strengthening effects of TMCP and retardation effects of austenite recrystallization with increasing Nb in austenite region, HTP conception with low...
Repeated deformation with optimum reductions in roughing mill exceeds the critical amount of strain required for recrystallization to occur. Recrystallization during roughing mill rolling refines austenitegrain size. The uniform recrystallized grain as a starting microstructure, further pancake grains during finishingmill rolling and accelerated cooling ensures fine grain microstructure in strip....
This paper analyzes precipitation anddislocation strengthening behaviors of a 27mm thick Niobium‐bearing Grade X80 steel plate for strain based design line pipe manufacture. The steel is produced by thermal‐mechanical processing (TMCP) and is characterized with granular bainite and polygonal ferrite microstructure. Mechanical properties of both the steel and the UOE pipe are briefly introduced. Transmission...
The paper provides a brief introduction of Niobium microalloy technology, which could refine the as‐rolled microstructure, inhibitthe grain growth during heating and soaking, strength steel dueto fine precipitates after tempering, increase hardenability, improve steel toughness and weldability. The research and application of Niobium‐bearing steels for low temperature service pressure vessels, such...
With the exploitation of gas mixed with sulfur, the requirement of hydrogen induced cracking (HIC) resistance for medium carbon vessels serving at environmental with hydrogen sulfide solution become more rigorous. Through the research on HIC, the formation reasons of those are: MnS inclusions, Al<sub>2</sub>O<sub>3</sub> inclusions, P segregation, Bainites and Macro segregation...
Extensive investigations of metallurgical roles played by Nb microalloying in advanced products of seamless steel tube have been carried out. The results show that with Nb microalloyed, the recrystallized austenite grain (RAG) and final ferrite grain of tubular steel are evidently refined even experiencing a piercing and a continuous rolling at very high temperature, and a certain quantity of (Nb,...
The article describes the production process and actual product properties of Cr‐Mo steel for gasifier developed by Wugang. By taking key technological measures such as optimized composition design, grain refining, microstructure homogenization, simulated post welding heat treatment process, Wugang has successfully produced SA387Gr11Cl2 steel plate under hydrogen environment, which satisfies the performance...
The effect of austenite deformation and continuous cooling on the evolutionof microstructure in a high temperature processing (HTP) concept pipeline steel was investigated in this research. It wasfound that without austenite deformation, the transformed microstructure consistsof blocky quasi‐polygonal ferrite (QF) grains and parallel bainiticferrite (BF) laths at a cooling rate of 0.5°C/s...
The microstructural development during roughing and early finishingof thick, high Nb‐Ti steels containing high and low Mn contentshas been investigated for conventional cold charging (CCR) and quasi compact strip production (CSP) conditions. Multi‐pass rolling simulations were performed, followed by interrupted accelerated cooling, to study the “as‐coiled” ferrite/pearlite microstructure...
The hot deformation behavior of nickel base superalloy 617B has been studied using hot compression experiments. Specimens were deformed in the temperature range of 1120‐1210°C with strain rates of 0.1 to 20 s‐1 and total strain of above 0.85. True stress‐true strain curves and deformation microstructures were studied. The results show that dynamic recrystallization is the mainly softening...
Three kinds of Nb‐Ti‐Mo ferrite matrix micro‐alloyed steels with three different Ti contents were designed. With optical microcopy, transmission electron microcopy, energy spectrum analysis and tensiletest, the microstructures, precipitate particles as well as mechanical properties of three steels were studied. The strength and toughness of steel with0.092% Ti content were verified to adequate for...
The corrosion of pipe is most common problem for oil and gas industry. In this article, three kinds of tubes will be analyzed in terms of their resistance against stress corrosion. They are respectively N80/1, N80/Q and P110. The loading method chosen in this test is constant tensile stress loading. In the test, samples will be separated in different groups, gradually loaded under specific levels...
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