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Stalheim D.G.,DGS Metallurgical Solutions , Inc. | Peimao F.,TISCO R and D | Linhao G.,Shougang R and D | Yongqing Z.,C1TIC Metal
7th International Conference on High Strength Low Alloy Steels, HSLA Steels 2015, International Conference on Microalloying 2015, Microalloying 2015 and International Conference on Offshore Engineering Steels 2015, OES 2015 | Year: 2015

Structural steels with yield strength requirements greater or equal to 690 MPa can be produced through controlled recrystallization hot rolling coupled with precipitation strengthening or purposeful heat treatment through quench and tempering (Q&T). High strength structural steel and wear/abrasion resistant requirements greater or equal to 360 Brinell hardness (BHN) are produced by the development of microstructures of tempered lower bainite and/or martensite through the Q&T process. While these Q&T microstructures can produce very high strengths and hardness levels making them ideal for 690 MPa plus yield strength or wear/abrasion resistant applications, they lack toughness/ductility and hence are very brittle and prone to cracking. While tempering the microstructures helps in improving the toughness/ductility and reducing the brittleness, strength and hardness can be sacrificed. In addition, these steels typically consist of alloy designs containing boron with carbon equivalents (CE) greater than 0.50 to achieve the desired microstructures. The higher CE has a negative influence on weldability. To achieve optimum mechanical properties, microstructure through either controlled recrystallization hot rolling coupled with precipitation strengthening or the Q&T process with the lowest CE and cost it is important that the metallurgical design engineer understands how to properly design the alloy (C, Mn, Si, Cr, Mo, Cu, Ni), the proper use of microalloy metallurgy, especially niobium and titanium, the proper rolling/cooling/QT process design and proper use of boron metallurgy. By having the proper understanding of an optimized metallurgical/alloy/process design will result in the proper cross sectional microstructure, optimum balance of strength, hardness, toughness, ductility, weldability and final shape achieved at the lowest cost This paper will explain the proper alloy, microalloy design, boron metallurgy and processing to produce optimized high strength/wear resistant structural steels at the lowest cost. This paper is the metallurgical basis of the implementation of optimized high strength/wear resistant steels used recently in China for the successful design of improved performance lighter weight heavy duty 150 ton haul truck buckets and 40 ton dump truck buckets.

Kendrick V.,Gallatin Steel Company | Frye B.,Gallatin Steel Company | McClure J.,Gallatin Steel Company | Holtman M.,Gallatin Steel Company | Stalheim D.G.,DGS Metallurgical Solutions , Inc.
Proceedings of the Biennial International Pipeline Conference, IPC | Year: 2014

Oil and gas exploration around the world continues at a rapid pace. This rapid pace of oil and gas exploration in North America has been fueled primarily thorough the development of horizontal drilling and the "fracking" process of underground shale formations. The demand for various grades and dimensions of API casing and pipe has and will continue to increase in the foreseeable future as these shale formations are exploited. To support this demand in North America, Gallatin Steel has embarked on a program to develop API casing and pipe coil skelp via their Compact Strip Plant (CSP). A key characteristic of API grade pipeline steels is excellent fracture toughness. This is one area where historically CSP facilities have struggled, especially in gauges greater than 8.8 mm (0.350") due to overall lack of reduction from the thin slab design of a CSP facility. In addition, utilizing the typical Thermomechanical Control Processing (TMCP) separating recrystallized and non-recrystallized rolling used in API coil skelp production for strength and toughness of a traditional HSM or plate mill is difficult to achieve in the continuous CSP facility. Gallatin Steel has successfully developed, through a controlled combination of slab quality, alloy design, process modifications and process control, excellent toughness in both charpy and DWTT performance from a 65 mm (2.56") slab in final coil thicknesses up to 12.7 mm (0.500"). This paper will describe the results achieved to date on various thicknesses from 7.6 mm to 12.7 mm API skelp development at Gallatin Steel. Mechanical property performance along with microstructures/grain size will be presented. In addition, future work that Gallatin Steel will undertake to further improve the capability to produce quality API coil skelp will be discussed. Copyright © 2014 by ASME.

Gu L.,Shougang Institute of Technology | Wang Z.,Shougang Institute of Technology | Zhang Y.,CITT Metal Co. | Guo A.,CITT Metal Co. | Stalheim D.,DGS Metallurgical Solutions , Inc.
7th International Conference on High Strength Low Alloy Steels, HSLA Steels 2015, International Conference on Microalloying 2015, Microalloying 2015 and International Conference on Offshore Engineering Steels 2015, OES 2015 | Year: 2015

Shougang Group has developed advanced high-strength wear-resistance steel of NM450 by using Nb-Mo-Cr-Ti-B micro-alloyed design and two-stage rolling and quenching and tempering process. In spite of high strength, the toughness and weldability of the steel was improved by reducing the carbon equivalent. For the high-strength wear-resistant steel, the yield strength is higher than HOOMPa, the tensile strength is higher than 1350MPa, the elongation is greater than 15%, the low temperature(-40°C) impact energy value is not less than 60J,and the Brinell hardness value of surface is more than 430HB. The abrasion resistance of NM450 is five times of that of the Q235.The high-strength wear-resistance steel is successfully applied in Shougang SGE150® heavy dump body to replace the plain carbon steel Q235, resulting in the reduction of body weight, the improvement of the life of the mine car and the reduction of the transportation costs.

Zhang G.,Qinhuangdao Shouqin Metal Materials Co. | Bai X.,Qinhuangdao Shouqin Metal Materials Co. | Stalheim D.,DGS Metallurgical Solutions , Inc. | Li S.,Shougang Institute of Technology | Ding W.,Shougang Institute of Technology
Proceedings of the Biennial International Pipeline Conference, IPC | Year: 2014

Along with the increasing demand of oil and natural gas by various world economies, the operating pressure of the pipeline is also increasing. Large diameter heavy wall X80 pipeline steel is widely used in the long distance high pressure oil and gas transportation in China today. In addition, development of X90/X100 has begun in earnest to support the growing energy needs of China. With the wide use of X80 steels, the production technology of this grade has become technically mature in the industry. Shougang Group Qinhuangdao Shouqin Metal Materials Co., Ltd. (SQS) since 2008 has been steadily developing heavier thicknesses and wider plate widths over the years. This development has resulted in stable mass production of X80 pipeline steel plate in heavy wall thicknesses for larger pipe OD applications. The technical specifications of X80 heavy wall thickness and X90/X100 14.8-19.6 mm wall thicknesses, large OD (48") requiring wide steel plates for the 3rd West-to-East Natural Gas Transmission Pipeline Project and the third line of Kazakhstan-China Main Gas Pipeline (The Middle Asia C Line) and the demonstration X90/X100 line (part of the 3rd West-East Project) in China required changes to the SQS plate mill process design. Considering the technology capability of steelmaking and the plate mill in SQS, a TMCP+OCP (Optimized Cooling Process) was developed to achieve stable X80 and X90/X100 mechanical properties in the steel plates while reducing alloy content. This paper will describe the chemistry, rolling process, microstructure and mechanical properties of X80 pipeline steel plates produced by SQS for 52,000 mT of for the 3rd West-to- East Natural Gas Transmission Pipeline Project and 5,000 mT for the Middle Asia C Line Project along with 1000 tons of 16.3 mm X90/X100 for the 3rd West-East demonstration pipeline. The importance of the slab reheating process and rolling schedule will be discussed in the paper. In addition, the per pass reductions logic used during recrystallized rough rolling, and special emphasis on the reduction of the final roughing pass prior to the intermediate holding (transfer bar) resulting in a fine uniform prior austenite microstructure will be discussed. The optimized cooling (two phase cooling) application after finish rolling guarantees the steady control of the final bainitic microstructure with optimum MA phase for both grades. The plates produced by this process achieved good surface quality, had excellent flatness and mechanical properties. The pipes were produced via the JCOE pipe production process and had favorable forming properties and good weldability. Plate mechanical properties successfully transferred into the required final pipe mechanical properties. The paper will show that the TMCP+OCP produced X80 heavy wall and 16.3 mm X90 wide plates completely meet the technical requirements of the three pipeline projects. Copyright © 2014 by ASME.

Park K.-J.,Hyundai Steel Technical Research Center | Park K.-J.,Sungkyunkwan University | Chul-Kim J.,Hyundai Steel Technical Research Center | Hwang S.-D.,Hyundai Steel Technical Research Center | And 3 more authors.
Proceedings of the International Offshore and Polar Engineering Conference | Year: 2016

This paper focuses on the recrystallization behavior to get low temperature Charpy V-notch toughness at -60 °C. Combination of Type I - Static Recrystallization and Type II - No Recrystallization, Type III Metadynamic (Partial)/Dynamic Recrystallization (simply Type III can be a mixture of Type I and Type II occurring at the same time) behavior is very important because austenite grain size depends on Type I and final grain size is affected by Type II & Type III highly. In this study, high mean flow stress and reduction ratio per pass were compared at finish rolling process. Our finding is to use steels at artic offshore structure until -60 °C, high mean flow stress is more effective than high reduction ratio per pass in rolling pass schedule because of the grain refinement by the partial dynamic recrystallization at finish rolling stage. © Copyright 2016 by the International Society of Offshore and Polar Engineers (ISOPE).

Drexler E.S.,U.S. National Institute of Standards and Technology | Slifka A.J.,U.S. National Institute of Standards and Technology | Amaro R.L.,U.S. National Institute of Standards and Technology | Barbosa N.,U.S. National Institute of Standards and Technology | And 3 more authors.
Fatigue and Fracture of Engineering Materials and Structures | Year: 2014

Hydrogen is known to have a deleterious effect on most engineering alloys. It has been shown repeatedly that the strength of steels is inversely related to the ductility of the material in hydrogen gas. However, the fatigue properties with respect to strength are not as well documented or understood. Here, we present the results of tests of the fatigue crack growth rate (FCGR) on API X70 from two sources. The two materials were tested in air, 5.5 and 34 MPa pressurized hydrogen gas, and at both 1 and 0.1 Hz. At these hydrogen pressures, the FCGR increases above that of air for all values of the stress intensity factor range (ΔK) greater than ~7 MPa · m1/2. The effect of hydrogen is particularly sensitive at values of ΔK below ~15 MPa · m1/2. That is, for values of ΔK between 7 and 15 MPa · m1/2, the FCGR rapidly increases from approximately that found in air to as much as two orders of magnitude above that in air. Above 15 MPa · m1/2, the FCGR remains approximately one to two orders of magnitude higher than that of air. © Published 2013. This article is a U.S. Government work and is in the public domain in the USA.

Stalheim D.G.,DGS Metallurgical Solutions , Inc. | Stalheim D.G.,Metals USA | Glodowski R.,DGS Metallurgical Solutions , Inc. | Glodowski R.,Metals USA
Iron and Steel Technology | Year: 2010

Production of a fine uniform cross-sectional grain size from grain-refining elements and processing/rolling schedule is discussed. Key variables that are responsible for the final cross-sectional grain size after rolling include total reduction, reheating time and temperature, roughing reduction schedule, and microalloy addition. When broadside passes are utilized, the total reduction ratio, as it relates to metallurgical considerations, should be calculated from the slab thickness at the end of the broadside passes. Some of the important points that need to be addressed in the roughing schedule that can affect the final cross-sectional ferrite grain size include the total reduction that occurs in the roughing passes should be at least 60% before the finishing passes start. Additional ferrite grain refinement can be realized from any microalloying element if some of the finish passes the temperature that is below than the recrystallization stop temperature.

Stalheim D.,DGS Metallurgical Solutions , Inc. | Jansto S.,CBMM Co.
Proceedings of the 10th International Conference on Steel Rolling | Year: 2010

The hot rolling of steel slabs produced from thin slab casters or billet casters and long products from bar and beam mills is the critical steelmaking step that adds the most value to the final hot roll product. Although hot rolling processes vary from continuous hot strip/sheet rolling mills to plate mills to Steckel mills to bar and beam mills, in many product sectors, all mill configurations are used in the production of similar finished product. This paper presents the universal heating, mechanical metallurgy, operational metallurgy and rolling mill practices that are essential in successfully producing high quality, value-added mieroalloyed steels. Differences in the importance of critical operational parameters are made comparing straight carbon-manganese steel versus mieroalloyed low carbon steels. More disciplined operational practices are reviewed that contribute to the successful rolling of these value added mieroalloyed steels. Reviews of the importance of a uniform cross sectional grain size and more importantly how to successfully produce it will be discussed. In many cases, optimization of metallurgy and mill capability are often overlooked or misunderstood. Optimization of the mill capability not only benefits productivity, but if done correctly can often result in overall improved metallurgy and hence optimization of the alloy design and final mechanical properties and in some cases shape. Regardless of the product sector, the end user demands steels exhibiting higher strength with improved toughness, better weldability, better formability, improved dimensional control, shape, profile and flatness. This can only be achieved through a thorough understanding of the metallurgy and more importantly how to get the most out of given mill's capability and configuration. Many of the newer mills and even some of the older ones have Level 2 automation models that generate the rolling schedule. Unfortunately, these models seldom incorporate metallurgical principals into the rolling logic and hence do not result in optimum rolling schedules for metallurgy or for that fact productivity. This paper will discuss issues with Level 2 models and what a mill owner should consider to get the most from the operation.

Stalheim D.G.,DGS Metallurgical Solutions , Inc. | Hoh B.,Process Technology Steel
Proceedings of the Biennial International Pipeline Conference, IPC | Year: 2010

Worldwide oil and natural gas reserves can be classified as either sweet or sour service. The sour service classified oil and natural gas reserves contain some level of H2S making the product flowing through a steel pipeline corrosive. Due to this, the majority of the oil and natural gas reserves that have been drilled are of the sweet service nature. However as demand continues and supplies change, many of the remaining oil and natural gas reserves contain the H2S component and are of a sour service nature. These oil and natural gas reserves containing the H2S component through a corrosion mechanism will allow for diatomic hydrogen - in the presence of moisture - to disseminate to monatomic hydrogen and diffuse into the pipeline steel microstructure. Depending on the microstructure and level of cleanliness the monatomic hydrogen can become trapped at areas of high residual stress, recollect to diatomic hydrogen and creating partial pressures that exceed the tensile strength of the steel resulting in cracking. Therefore transmission pipelines are being built to transport sour service oil or natural gas requires steels with hydrogen induced cracking (HIC) resistance. Alloy designs, steel making processing, continuous casting, plate or strip rolling, pipe forming, and last not least corrosion testing are all key components in producing pipeline steels that are resistant to HIC applications and meeting the NACE TM0284 specifications. However, producing steels that have good HIC performance do not necessarily meet other mechanical property requirements such as strength and YT ratios. Balance has to be achieved to meet not only the HIC requirements but the other required mechanical properties. Mastering this complex HIC process poses a serious challenge to pipe producers and their primary material suppliers. The capability of producing HIC steel grades according to critical specifications and/or standards clearly distinguishes excellent steel producers from good steel makers. This paper will discuss the basics of the hydrogen induced cracking phenomenon, the requirements of the NACE TM0284 specification and give guidelines for steel production of API pipeline steels that not only can meet the specification requirements the NACE testing but also fulfill the other mechanical property requirements. Copyright © 2010 by ASME.

Hayden L.E.,Lafayette College | Stalheim D.,DGS Metallurgical Solutions , Inc.
American Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP | Year: 2010

The ASME B31.12 Hydrogen Piping and Pipeline Code has just been published for use in designing hydrogen piping and pipeline systems. The B31.12 Committee has developed two design methods that take current steel specifications and chemical compositions into consideration. Due to the variability of chemistry and the lack of statistically meaningful test data these two methods place a design or testing burden on the owner of the pipeline or piping system. Research and development that can be applied to an understanding of the desirable microstructure along with a cleanliness level that is suitable in commercial grade steels for hydrogen service is imperative. Copyright © 2009 by ASME.

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