China First Heavy Industries

Tianjin, China

China First Heavy Industries

Tianjin, China
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Lou L.,Tianjin University | Li H.,Tianjin University | Shen J.,Tianjin University | Gu W.,China First Heavy Industries
Hanjie Xuebao/Transactions of the China Welding Institution | Year: 2017

Nuclear vessel head is constituted by intersection structure of sphere and a given number of tubes. The welding groove is called J groove, its welding seam is irregular space curve, and its position is inside the vessel head. The welding efficiency and quality is not good with common manual welding method for J-groove. This paper proposed a multi-pass filling strategy of J-groove automatic welding process for one type nuclear power pressure vessel head. Through the analysis of welding structure, the region division of welding process and filling strategy is determined. And the selection rule of welding process parameters is put forward to control the welding appearance. The tests indicate that suitable welding appearance can be obtained through the proposed strategy. © 2017, Editorial Board of Transactions of the China Welding Institution, Magazine Agency Welding. All right reserved.

Xu Y.,Shanghai JiaoTong University | Nie Y.,China First Heavy Industries | Wang M.,Yanshan University | Li W.,Shanghai JiaoTong University | Jin X.,Shanghai JiaoTong University
Acta Materialia | Year: 2017

The evolution of the microstructure and its effect on mechanical properties of a 10% Cr steel under long-term aging at 650 °C have been investigated. During short-term aging (<6000h), the reduction of room temperature hardness and yield strength are mainly caused by the decline of dislocation density. However, under long-term aging (from 6000h to 38200h), they are directly attributed to the coarsening of subgrains. The coarsening kinetics of Laves phase (≥18000h), M23C6 carbides and MX carbonitrides are well consistent with the ripening model in multicomponent alloys. Before 18000h, the coarsening of Laves phase is strongly affected by the swallowing growth mechanism. The plasticity in terms of fracture elongation at room temperature shows a non-monotonic dependence on the aging time, the effect factors such as dislocation density, strain level and distribution, subgrain width, precipitates size and ratio of brittle phase interfaces have been studied in detail. During tensile deformation, the large and irregular Laves phase particles induce severe strain localization and tend to form large strain concentration block. It is found that deterioration of plasticity is dominated by severely inhomogeneous and large size of Laves phase caused by two different nucleation and growth mechanisms and high coarsening rate (∼32.0 nm/h1/3), rather than the increase in the ratio of brittle phase interfaces. The swallowing growth mechanism for Laves phase, growing by swallowing the adjacent M23C6 carbides, has been emphatically discussed. © 2017 Acta Materialia Inc.

He J.,Shanghai JiaoTong University | Gao F.,Shanghai JiaoTong University | Bai Y.,Shanghai JiaoTong University | Wu S.,China First Heavy Industries
Chinese Journal of Mechanical Engineering (English Edition) | Year: 2013

The large capacity servo press is traditionally realized by means of redundant actuation, however there exist the over-constraint problem and interference among actuators, which increases the control difficulty and the product cost. A new type of press mechanism with parallel topology is presented to develop the mechanical servo press with high stamping capacity. The dynamic model considering gravity counterbalance is proposed based on the virtual work principle, and then the effect of counterbalance cylinder on the dynamic performance of the servo press is studied. It is found that the motor torque required to operate the press is a lot less than the others when the ratio of the counterbalance force to the gravity of ram is in the vicinity of 1.0. The stamping force of the real press prototype can reach up to 25 MN on the position of 13 mm away from the bottom dead center. The typical deep-drawing process with 1 200 mm stroke at 8 strokes per minute is proposed by means of five order polynomial. On this process condition, the driving torques are calculated based on the above dynamic model and the torque measuring test is also carried out on the prototype. It is shown that the curve trend of calculation torque is consistent to the measured result and that the average error is less than 15%. The parallel mechanism is introduced into the development of large capacity servo press to avoid the over-constraint and interference of traditional redundant actuation, and its dynamic characteristics with gravity counterbalance are presented. © Chinese Mechanical Engineering Society and Springer-Verlag Berlin Heidelberg 2013.

Meng X.,Shanghai JiaoTong University | Gao F.,Shanghai JiaoTong University | Wu S.,China First Heavy Industries | Ge Q.J.,Shanghai JiaoTong University | Ge Q.J.,State University of New York at Stony Brook
Mechanism and Machine Theory | Year: 2014

The research on type synthesis of parallel mechanisms (PMs) attracted adequate attention with the development of several distinctive methodologies in the robotics area. As the foundation of innovative products design, type synthesis, the most original part of mechanical system design, is endowed with important theoretical and practical value. Based on the review on several distinctive approaches, the framework of the type synthesis of PMs is studied in this paper. Reasoned and comprehensive introduction is provided for the five basic issues of the type synthesis of PMs. The research status and existing problems of these issues in distinctive approaches are investigated. The framework of the type synthesis of PMs constructed in this paper would provide a unified platform for communications and references among different approaches. © 2014 Elsevier Ltd.

He J.,Shanghai JiaoTong University | Gao F.,Shanghai JiaoTong University | Wu S.,China First Heavy Industries | Liu R.,Shanghai JiaoTong University | Zhao X.,Shanghai JiaoTong University
Measurement: Journal of the International Measurement Confederation | Year: 2012

During the industrial forging or rolling of hot steel shells, the raw material utilization ratio is very low because of the absence of precise on-line measurement instrument for the forging dimensions. In order to reduce the waste and increase the productivity, the pulse laser measuring instrument with dual PRRR mechanism has been developed in this study. The adjusting algorithm of rotary table based on the dual PRRR mechanism has been presented, which ensures that the scanning plane is perpendicular to the axis of cylinder shell. So the circle fitting can be adopted and the robust and accurate dimensions can be obtained rapidly by the present data-processing method. The measurement error of cold cylinder shell's diameter is less than 3 mm. The measuring results of hot steel shells are also very accurate. The present system has been used in the rolling production of large hot steel shells, which enhances the raw material utilization ratio during the rolling. © 2012 Published by Elsevier Ltd. All rights reserved.

Nie Y.,Japan National Institute of Materials Science | Kimura Y.,Japan National Institute of Materials Science | Inoue T.,China First Heavy Industries | Yin F.,China First Heavy Industries | And 2 more authors.
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2012

A deformation of a tempered martensitic structure (i.e., tempforming) at 773 K (500°C) was applied to a 0.6 pct C-2 pct Si-1 pct Cr steel. The hydrogen embrittlement (HE) property of the tempformed (TF) steel was investigated by a slow strain rate test (SSRT) and an accelerated atmospheric corrosion test (AACT). Hydrogen content within the samples after SSRT andAACT was measured by thermal desorption spectrometry (TDS). The tempforming at 773 K (500°C) using multipass caliber rolling with an accumulative are reduction of 76 pct resulted in the evolution of an ultrafine elongated grain (UFEG) structure with a strong h110i//rolling direction (RD) fiber deformation texture and a dispersion of spheroidized cementite particles. The SSRT of the pre-hydrogen-charged notched specimens and the AACT demonstrated that the TF sample had superior potential for HE resistance to the conventional quenched and tempered (QT) sample at a tensile strength of 1500 MPa. The TDS analysis also indicated that the hydrogen might be mainly trapped by reversible trapping sites such as grain boundaries and dislocations in the TF sample, and the hydrogen trapping states of the TF sample were similar to those of the QT sample. The QT sample exhibited hydrogen-induced intergranular fracture along the boundaries of coarse prioraustenite grains. In contrast, the hydrogen-induced cracking occurred in association with the UFEG structure in the TF sample, leading to the higher HE resistance of the TF sample. © 2011 The Minerals, Metals & Materials Society and ASM International.

Rong J.H.,Yanshan University | Hong X.,Yanshan University | Xiang G.Y.,Yanshan University | Shui J.J.,China First Heavy Industries
Applied Mechanics and Materials | Year: 2014

In order to effectively improve the calculation accuracy of finishing rolling force model for hot rolling wide and heavy stainless steel clad sheets, based on the E.Orowan unit pressure equilibrium differential equations and R.B.Sims unit pressure formulas, this paper divides hot-rolled composite deformation area into I, II two zones according to rolling stock jamming experiment, and then derives the finishing rolling force calculation formulas. Finally, by ANSYS/LS-DYNA thermal-mechanical coupling simulation and experiment, the results show that compared with measured values, the relative error of simulated values is about 20%, the relative error of calculated values is less than 10%. Therefore, the rolling force model can accurately predict the size of rolling force and effectively improve the calculation accuracy of rolling force. © (2014) Trans Tech Publications, Switzerland.

Qu M.-G.,Yanshan University | Sun S.-H.,Yanshan University | Bai X.-H.,China First Heavy Industries | Shi Z.-P.,Yanshan University | And 2 more authors.
Journal of Iron and Steel Research International | Year: 2014

The hot deformation behavior of as-cast AISI M2 high-speed steel containing mischmetal (RE) has been investigated on a Gleeble-3500 simulator in the temperature range of 1000-1150 °C and strain rate range of 0. 01 - 10 s-1 at true strain of 1.0. The mechanical behavior has been characterized using stress-strain curve analysis, kinetic analysis, processing maps, etc. Metallographic investigation was performed to evaluate the mechanism of flow instability. The results show that the deformation activation energy decreases with increasing deformation temperature; the efficiency of power dissipation increases with decreasing strain rate and increasing temperature; flow instability is observed at low-to-medium temperature and higher strain rate region when the strain is smaller, but extends to lower strain rate and high temperature regions with the increment of strain, in which it is manifested as flow localization near the grain boundary. Hot deformation equations and processing maps are obtained. The optimal processing window is suggested and the deformation mechanism is dynamic recrystallization (DRX). © 2014 Central Iron and Steel Research Institute.

Xie Y.,China First Heavy Industries
Hanjie Xuebao/Transactions of the China Welding Institution | Year: 2015

The weldability of A517Q rack steel was investigated systematically by means of oblique Y-groove cracking tests, maximum hardness tests on the heat affected zone (HAZ) and the mechanical property tests of welded joint. The results showed that under the restraint condition, the cold crack susceptibility of A517Q weld was increased with the thickness of tested plates increasing from 30 mm to 60 mm. Raising preheating temperature contributed to the reduction of cold crack tendency of steel and the hard level of HAZ. The welded joint of 177.8 mm thick A517Q rack steel plate exhibited high strength and toughness, meeting the requirements of usage. The microstructure of HAZ mainly consisted of lath-like martensite and lath-like bainite. The hardness of HAZ apparently exceeded weld metal zone and the parent metal, presenting a high harden tendency and a certain risk of cold cracking. ©, 2015, Harbin Institute of Technology. All right reserved.

Wenhui Z.,Yanshan University | Shuhua S.,Yanshan University | Deli Z.,China First Heavy Industries | Baozhong W.,China First Heavy Industries | And 2 more authors.
Materials and Design | Year: 2011

A Nb-containing 316LN stainless steel was compressed in the temperature range 900-1200°C and strain rate range 0.01-10s-1. The mechanical behavior has been characterized using stress-strain curve analysis, kinetic analysis, processing maps, etc. The microstructural evolution was observed and the mechanism of flow instability was discussed. It was found that the work hardening rate and flow stress decreased with increasing deformation temperature and decreasing strain rate. On the contrary, the efficiency of power dissipation increased with them; Flow instability was manifested as cracking and flow localization; The hot deformation equation and the relationships between deformation condition and dynamic recrystallization grain size and fraction were obtained; For Nb-containing 316LN stainless steel, the favorite nucleation sites for dynamic recrystallization are in sequence of triple point, grain boundary, twin boundary and intragranular deformation band; The suggested processing window is given. © 2011 Elsevier Ltd.

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