This is a comprehensive report on the API pipeline grades production. It covers a broad range of topics such as requirements, development history, production technology on alloying, thermomechanical rolling, controlled cooling, and finish quality and properties prediction, etc. The report is created under tight combination of the publications worldwide, technical partnership with various developers, and in particular, the intensive development of Metal Pass in recent years in several steel plate steckle mills in USA and China. <Read in Full>
A Set of Manufacturing Technologies for High Performance Steel Plates This report introduces a set of plate manufacturing technologies for high performance steel plates. An accelerated cooling technology for plates with a high cooling capacity achieves the theoretical cooling limit and uniform cooling performance. An induction heating-type on-line heat-treatment process which reduces delivery times is included. Making full use of these plate manufacturing technologies enables development of high quality, high performance plates for a wide range of fields. <Read in Full>
Metallurgical Characteristics and Manufacturing Technologies of High Strength Linepipes While natural gas pipelines are expanding to remote regions and regions under severe environmental conditions, requirements are high for linepipe materials to have higher strength with properties suitable for the environment, such as high deformability or sour gas resistance. A series of high strength UOE linepipes have been developed with various excellent properties by applying cutting edge accelerated cooling and heat-treatment process. This document introduces characteristics of the recently developed UOE linepipes and metallurgical controlling technologies. <Read in Full>
High Performance Steel Plates Produced with Advanced Controlled-Cooling Technologies Recent development of construction and design technology gives larger and heavier steel structures. In addition, reductions of construction and maintenance cost are also recently focused in various fields. From this viewpoint, higher strength, better weldability and higher performance are required for structural steels. In order to achieve these requirements, advanced and sophisticated process technology is critical in addition to precise material design. This paper describes the development of the advanced Accelerated Cooling) and its various products. <Read in Full>
A Short Report on Microstructure, Properties and a new Metallographic Technique Modern steels are often comprised of mixtures of polygonal ferrite, non-polygonal ferrite, acicular ferrite, granular bainite, lower bainite, martensite and retained austenite. These structures are not only complex, but also often very fine in scale. This report is to describe, characterize and quantify complex microstructure, based on the EBSD-IQ that can be generated by modern OIM packages fitted to FEG-SEM microscopes. A history review on achievable yield strength (YS) levels starting from 1950s is also provided. <Read in Full>
Copper precipitates in ferrite matrix in linepipe steels Even low amounts of copper (e.g. ~0.4wt.%) can contribute to strengthening of the steel. Copper can contribute to solid solution strengthening of steels. Copper precipitation is expected to take place in Cu-bearing steels. In this study, steels containing Mo and different Nb and Cu levels were subjected to small amounts of plastic deformation in the ferrite region (400°C) followed by air-cooling to investigate its effects. <Read in Full>
Effect of Thermomechanical Processing Parameters on the Mechanical Properties of API X80 Steel The mechanical properties of API high strength steel grades can be remarkably improved through proper chemistry selection and an appropriate thermomechanical processing (TMP) that refine and homogenize the final microstructure and form the required phases. This paper describes the effect of different hot strip mill (HSM) processing parameters on the microstructure and mechanical properties of API X80 steel. <Read in Full>
The Effect of Processing Conditions and Cooling Rate on API X-70 and X-100 Grade Steels This investigation on the specimens from X-70 and X-100 compositions, TMCP parameters and accelerated cooling rates revealed the effects on the final material properties. The results of this study show key factors in controlling the microstructural and mechanical properties of the final steel products. A total of two different deformation temperatures, namely, 950 and 850ºC were used for the present experiments, in which multi-pass isothermal deformation took place, after which cooling commenced at one of two possible rates, 15°C/sec. or 6°C/sec. <Read in Full>
Laminar Flow Cooling Behavior of Wide Heavy-Thickness Coils The bottom cooling headers with double-set nozzles have been proposed to minimize transverse canoe (or crossbow) and to improve longitudinal uniformity of mechanical properties. A control model with proper ratios of the bottom flow rate to the top flow rate is developed. Three basic laminar flow patterns are introduced. Combining the heat transfer with phase transformation, mechanical properties of wide heavy-thickness coils are predicted. <Read in Full>
Introduction to TTT and CCT Diagrams This 20-page document covers fundamental issues on the continuous cooling transformation. There are two forms of transformation diagrams, such as the time-temperature transformation (TTT) and the continuous cooling transformation (CCT) diagrams, which are commonly used by metallurgists to assess the microstructure produced during heat treatment, and provide a judgment of the hardenability of a steel. <Read in Full>
2004 Nippon Steel Technical Report on Linepipes Nippon Steel has established the integrated production technology of linepipes. The principal elementary technologies are the following: controlled rolling and thermo-mechanical control processing (TMCP); steel chemistry of low-C-Nb systems containing other strengthening elements (B, Mo, etc.) in consideration of weldability; process metallurgy (thermo-mechanical control process) on the basis of the steel chemistry; and so on. <Read in Full>
Development of Ultra-high-strength Linepipe with Grade X120 An ultra high-strength grade of large diameter linepipe, X120 that far exceeds the conventional grades of X65 and X80, has been developed. Significantly advanced production technology is required for the manufacture of the X120 pipe. To realize this, research and development activities in all the fields such as material design, steelmaking, casting, plate production and pipe production (UOE press forming and seam welding) were carried out in an organically integrated manner. <Read in Full>
High-strength Linepipes with Excellent HAZ Toughness The production technologies of UOE pipes up to grade X100 having excellent low-temperature toughness and large uniform elongation have been discussed herein. For improving the HAZ toughness of a linepipe of grade X80 or lower, it is highly effective to inhibit the coarsening of γ grains near an FL and form IGF in order to make the microstructure of a HAZ fine. For improving the HAZ toughness of an X100 linepipe, on the other hand, it is necessary to lower C content to 0.04% or less. …… <Read in Full>
Microstructure and Mechanical Properties of X80/X100 Plates and Pipes An overview of the manufacturing technology for X80/X100 grade linepipe steel was introduced. Through the UOE simulator, the changes of mechanical properties after pipe forming from plate to pipe were tested and understood. Especially, the microstructure and mechanical properties of X80/X100 steel plates and pipes were analyzed and discussed. Also, an experimental test to determine the critical compressive strain of X80 pipe in combination of bending and axial force was performed. <Read in Full>
Classification of Thermomechanical Treatment The ferrous TMT process may be classified into three broad categories, depending on the introduction of the deformation process before, during, or after the phase transformation. Class 1: Deformation is completed prior to the transformation of austenite; Class 2: Deformation occurs during the transformation of austenite; and Class 3: Deformation occurs after the transformation of austenite. <Read in Full>
Metallurgical Design for Steel Strengthening Metallurgical design for steel strengthening basics are introduced at first. Then, 9 strengthening mechanisms are discussed consisting of: (1) Substitutional Solid-Solution Strengthening, (2) Interstitial Solid Solution Strengthening, (3) Substitutional-Interstitial Solute Interaction Strengthening, (4) Precipitation Strengthening, (5) Strengthening With Niobium, (6) Strengthening With Vanadium and Nitrogen, (7) Strengthening With Titanium, (8) Dislocation Strengthening, and (9) Second-Phase Strengthening. <Read in Full>
