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Zhang M.,Shanghai University | Wan Z.,Shanghai Huizhong Automotive Manufacturing Co. | Li L.,Shanghai University
Materials Today: Proceedings | Year: 2015

Continuous cooling transformation characteristics of steel 22MnB5 were studied in detail using dilatometer method. The influence of hot forming procedure parameters, such as heating rate, austenizing temperature, and holding time on microstructure transition was analyzed. Microhardness was tested afterwards. The microstructure obtained from the dilatometer samples reveals that for heating temperatures above 850°C samples fast heated for 10s holding couples with full austenite transformation and can get a fully martensitic microstructure after immediately quenching with 30°C/s cooling rate. The same is for samples heated with 10°C /s to 930, 900, 880, 860, and 840°C for 300s holding conditions. In the studied cases, hardness of the samples is around 500HV. Hot stamping V-type automotive parts were subsequently manufactured using a self-designed special tool set with cooling system in it, heating to 860, 880, 900, and 920°C for 300s holding correspondingly, following die quenching as soon as possible. The tensile strength of the parts reaches 1500MPa, and total elongation A80 achieves 8%. It is found that heating temperature lower to 880°C is good for getting a much finer fully martensitic microstructure, and a better property combination. © 2015 The Authors.

Zhang M.,Shanghai University | Li Q.,Shanghai University | Huang C.,Shanghai University | Wu R.,Shanghai University | And 3 more authors.
Advanced Materials Research | Year: 2013

Complex phase steel CP 800, a kind of advanced high strength steel (AHSS), exhibited quite high carbon equivalent (CE) which was a detrimental factor for weldability of steels. Thus the weldability of CP 800 steels containing (in wt%) 0.06C-0.45Si-1.71Mn-0.11Ti was extensively studied. Mechanical properties and impact toughness of butt joint, the welding crack susceptibility of weld and heat-affected-zone (HAZ) for tee joint, Control Thermal Severity (CTS) welded joint, and 60°Y-groove butt joint were inspected after gas shielded arc welding tests. The impact toughness was larger than 27J either at room temperature (RT) or at -20°C, indicating good impact toughness of the weld of the steel. In addition, welding crack susceptibility tests revealed that the weldments were free of surface crack and other imperfection, showed fairly good weldability. In application, the longitudinal control arm of automobile made of this steel exhibited excellent fatigue and durability performance. © (2013) Trans Tech Publications, Switzerland.

Yang Y.-T.,Shanghai University | Yin X.-L.,Shanghai University | Sun B.-L.,Shanghai Huizhong Automotive Manufacturing Co. | Zhang H.-H.,Shanghai University | And 2 more authors.
Transactions of Nonferrous Metals Society of China (English Edition) | Year: 2010

The hypoeutectic Al-Si alloy billet with non-dendrite was reheated to meet the needs of the semi-solid thixoforming microstructure by four kinds of reheating power, achieving the same final temperature of 851 K. Subsequently, under the same condition of thixoforming, the microstructure, surface hardness and tensile properties were observed. Afterwards, quantitative analysis was made for the microstructures of the reheated semi-solid of billet and the thixoforming parts. The results show that when the induction reheating power is 90 kW, the average grain size of the semi-solid billet is the minimum, the microstructures of the thixoforming samples also are the finest, and the mechanical properties of the relevant thixoforming samples are the best. Furthermore, after studying on the relationship between the microstructures of the semi-solid billet of aluminum alloy and the mechanical properties of the thixoforming samples, the reverse design of microstructure is primarily achieved. Finally, the effectiveness of the reverse design for semi-solid microstructure is confirmed by an actual automobile part with complex shape. © 2010 The Nonferrous Metals Society of China.

Zhang M.,Shanghai University | Ning Y.X.,Shanghai University | Zhang J.,Shanghai University | Wan Z.,Shanghai Huizhong Automotive Manufacturing Co. | Wang T.,Shanghai Huizhong Automotive Manufacturing Co.
Applied Mechanics and Materials | Year: 2014

800MPa grade Advanced High Strength Steels (AHSS), including Complex Phase steel CP800 and Ferrite-Bainite steel FB800, were chosen to test the forming performance in different test conditions and compared with the reference traditional high strength low alloy (HSLA) steels HR700LA. Tensile test, hole expansion (HE) test, and HAT shape stamping test were taken to investigate the forming performance of the materials. Test results indicated that the studied 800MPa grade AHSS showed a better strength ductility balance compared with the reference steel. Among all the steels researched, FB800 showed the best hole expansion ratio(HER), and CP800 the worst. Springback angles of AHSS after HAT shape stamping tests were markedly smaller than those of HR700LA steels, though the springback angles of HR700LA decreased continuously with blank holding force(BHF) increasing. Steel FB800, CP800S and CP800B had much better shape stability compared with steels HR700LA. AHSS showed much smaller springback behavior under the same stamping condition, especially for steels CP800-B, FB800-2 and FB800-1. When increasing the BHF to 100KN, AHSS showed the largest springback deformation. Among the three kinds of CP800 steels researched, steel CP800-B indicated outstanding springback restrain trend in BHF further increasing attempt. So, springback behavior could be restricted obviously by using a larger BHF in AHSS CP800B forming operations. © (2014) Trans Tech Publications, Switzerland.

Gui L.M.,Shanghai Huizhong Automotive Manufacturing Co. | Jin X.C.,Shanghai Huizhong Automotive Manufacturing Co. | Li H.T.,Shanghai University | Zhang M.,Shanghai University
Advanced Materials Research | Year: 2014

A low carbon content and improved steel making practices have imparted advanced high strength steel (AHSS) CP800 with superior combination of strength, ductility and weldability. Its performance in fatigue, however, is not well understood. Stress-controlled high cycle fatigue (HCF) tests were conducted to obtain stress vs. fatigue life curve (S-N curve), and the fatigue limit of CP800. The follow HCF performances were obtained. σ0.1476MPa, SRI1 = 1940MPa, b=-0. 09972, Nc1=2. 89×106, and R2= 0. 88. The collected material data are used as a basis of comparison of CP800 with more common grades of structural steel. CP800 steel shows high strength, comparable ductility, and high fatigue limit level. The test results indicate that compare to that of lower strength common grades of structural steels, CP800 steel has a much higher fatigue endurance limit (say, 476MPa), about 0. 6 of its tensile strength (TS). Thus, provides a distinct advantage. © (2014) Trans Tech Publications, Switzerland.

He Y.,Shanghai Huizhong Automotive Manufacturing Co. | Wu H.,Shanghai JiaoTong University | Li X.,Shanghai JiaoTong University | Mao Q.,Shanghai Huizhong Automotive Manufacturing Co.
Cailiao Kexue yu Gongyi/Material Science and Technology | Year: 2015

To optimize stamping process parameters and improve the stamping process robustness for high strength steel control arm, the 6sigma robust design theory based numerical simulation is utilized to reveal the effects of preforming die gap, local flanging die gap, preforming blankholder force, friction coefficient, blank outline dimension, etc., on thickness thinning ratio at the corner. The noise variables, such as blank position, blank thickness, friction coefficient, plastic strain ratio, yield stress, ultimate tensile stress, blank size, etc., are input, and the process robustness is simulated. Based on the sensitivity analysis results, the optimization calculation is performed by setting the local flanging die gap and performing die gap as variables, and 3sigma quality level and Cp=1 as an object. Finally, the robustness analysis is carried on again by optimized local flanging die gap and preforming die gap. It's found that the preforming die gap and local flanging die gap are the primary factors that affect excessive thinning and crack of control arm. The maximum error of thickness distribution between simulation and trial is less than 6%. By sensitivity analysis of key parameters and robustness analysis of noise parameters, the high and reliable quality level is achieved. ©, 2015, Harbin Institute of Technology. All right reserved.

Shen Y.-F.,University of Shanghai for Science and Technology | Shen Y.-F.,Shanghai Dianji University | Zheng S.-L.,University of Shanghai for Science and Technology | Wang Z.-R.,Shanghai Huizhong Automotive Manufacturing Co.
Journal of the Chinese Society of Mechanical Engineers, Transactions of the Chinese Institute of Engineers, Series C/Chung-Kuo Chi Hsueh Kung Ch'eng Hsuebo Pao | Year: 2015

A program load spectrum compiling method for automotive components was introduced with swing arm as example. Based on low loading strengthening property, a spectrum compiling method considering the strengthening effective loads is put forward, which overcomes the deficiency of the traditional methods, in which only the damage effect of low amplitude loads is considered. By transferring the strengthening loads to the most effective level, the bench tests show that the total cycling blocks decline sharply under homemade specification. It proves that while deleting the useless loads during the spectrum compiling process, the strengthening loads' influence should be taken into account. Moreover, the real service condition of automotive parts by simulation can be faster and more real, and it is significant to predicate the failure mode of durability tests and to estimate service life of automotive parts more accurately. © 2015, Chinese Mechanical Engineering Society. All right reserved.

Lang L.,Beihang University | Zhang F.,Beihang University | Cheng P.,Beihang University | Wang T.,Shanghai Huizhong Automotive Manufacturing Co.
Zhongguo Jixie Gongcheng/China Mechanical Engineering | Year: 2014

The multi-step hydroforming process of trailing arm which is one of the typical automotive chassis parts was optimized by numerical simulation and experiments. In order to improve forming efficiency and quality consistency, a multi-cavity mould was used and the influences of tool lay-out on hydroforming process were studied. It is a reasonable tool lay-out that hydroforming tool has symmetrical distribution with two “C” shapes compared to other ones. It can improve the stress condition of the tool and parts during hydroforming process and make the quality of the forming parts be guaranteed, as well as enhance the production efficiency. ©, 2014, Zhongguo Jixie Gongcheng/China Mechanical Engineering. All right reserved.

Fang M.,Tongji University | Tan J.,Shanghai Huizhong Automotive Manufacturing Co. | Xu G.,Shanghai Huizhong Automotive Manufacturing Co.
Qiche Gongcheng/Automotive Engineering | Year: 2013

A method by combining test and finite element analysis, with maximum strain energy density as parameter to predict the fatigue life of vehicle rubber bushings is proposed in this paper. Firstly a vehicle stochastic nonlinear dynamic model is set up using dynamic substructure technique. Then Monte Carlo method is used to simulate the random excitations of road surface and engine, and the displacement, velocity and acceleration responses of rubber bushings in vehicle under those excitations are obtained. Finally with these response characteristics as excitations to the FE model for rubber bushing, the maximum strain energy density is obtained, by which the fatigue life of rubber bushings under random load excitation is predicted with fatigue life prediction model. The results of verification by the fatigue test on front engine cradle show that the method proposed has reasonable accuracy in predicting the random fatigue life of vehicle rubber bushings.

Tao L.,Shanghai Huizhong Automotive Manufacturing Co. | Ou C.,Shanghai Huizhong Automotive Manufacturing Co. | Xu J.,Shanghai Huizhong Automotive Manufacturing Co. | Yao J.,Shanghai Huizhong Automotive Manufacturing Co.
Tezhong Zhuzao Ji Youse Hejin/Special Casting and Nonferrous Alloys | Year: 2015

According to the shape characteristics of casting aluminum alloy knuckle and actual production capacity, the forming process of aluminum alloy knuckle was analyzed by MAGMA software. Based on numerical simulation, the structure and casting process parameters of the aluminum knuckle were optimized. Finally, the steering knuckle has been proved to meet the operating requirements through an experimental verification. Consequently, a feasible process of trial production of the steering knuckle has been explored. © 2015, Journal Office of Special Casting and Nonferrous Alloys. All right reserved.

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