Mechanical Analysis on the Inner Surface Crack of Modified 9Cr-1Mo Seamless Steel Tubes Rolled by Mandrel Mill

2010 ◽  
Vol 97-101 ◽  
pp. 3070-3074
Author(s):  
Sheng Zhi Li ◽  
Jie Xu ◽  
Yuan De Yin ◽  
Hui Chao Su
Keyword(s):  
Surface Crack ◽  
Production Efficiency ◽  
Circumferential Stress ◽  
Rolling Process ◽  
Mechanical Analysis ◽  
Steel Tube ◽  
Roll Pass ◽  
Steel Tubes ◽  
Inner Surface ◽  
Seamless Steel

The inner surface crack (ISC) defect easily occurs in seamless modified 9Cr-1Mo steel tubes rolled by the mandrel mill with high production efficiency. The reason for the formation of the ISC lies in both the properties of deformed material and rolling conditions. With the aid of commercial FE code MSC.SuperForm, the rolling process of modified 9Cr-1Mo seamless steel tube produced by the Mandrel Mill of Bao Steel in China was simulated, focusing on mechanical analysis of deformed metal. It was found from the simulation that the metal on the inner surface of the tube, in the position of 0 or 90 of the roll pass, experiences strong tensile stresses, especially the circumferential stress, which is closely related .to the strain behavior governed by the two-high pass caliber of the mandrel mill. Therefore an optimal design of the roll pass can be realized to decrease the tensile stress so as to relax the tendency to the ISC, which has been confirmed by the tests in Steel Tube & Pipe Company of Bao Steel.

The Study of Inner Surface Crack Formation of Seamless Modified 9Cr-1Mo Tube Rolled on Mandrel Mill and Its Application

2007 ◽  
Vol 561-565 ◽  
pp. 61-64
Author(s):  
Sheng Zhi Li ◽  
Jie Xu ◽  
Yuan De Yin ◽  
J.G. Xue ◽  
Y. Feng
Keyword(s):  
Surface Crack ◽  
Crack Formation ◽  
Metal Flow ◽  
Rolling Process ◽  
Hot Workability ◽  
Roll Pass ◽  
Pass System ◽  
Boiler Tubes ◽  
Inner Surface ◽  
Heat Resistant Steels

The hot workability of modified 9Cr-1Mo, as a grade of heat resistant steels, is inferior to that of low-alloy steel, so the inner surface crack (ISC) easily occurs in seamless boiler tubes produced by the Mandrel Mill under improper rolling conditions. With the aid of FEM, the metal flow status during the rolling process was analyzed in 140mm 8-stand mandrel mill of Bao Steel. Both the metallographic shape and size of the ISC together with the result from the simulation show that the ISC of seamless tube forms at the elongation stage of shell. The mechanism of the ISC was discussed. With its initiation in stand No.1 and No.2 due to poor hot workability of modified 9Cr-1Mo steel, the ISC develops in subsequent passes. Based upon the mechanism devised was a special roll pass system which substantially upgraded the yield of qualified products.

Research on Design Method of Polygonal Roll Pass for Stretch Reduced Seamless Tubes

2010 ◽  
Vol 654-656 ◽  
pp. 1614-1617 ◽  
Author(s):  
Sheng Zhi Li ◽  
Hai Yan Bao ◽  
Zhi Chao Zhang ◽  
Yang Hua Li ◽  
Gong Ming Long
Keyword(s):  
Wall Thickness ◽  
Design Method ◽  
Element Model ◽  
Rolling Process ◽  
Contact Length ◽  
Transverse Wall ◽  
Roll Pass ◽  
Steel Tubes ◽  
Pass System ◽  
Lateral Curvature

the aid of commercially available software MSC.SuperForm, a 3-D finite element model has been established to simulate the rolling process of steel tubes on the stretch reducing mill (SRM) with group centralized differential drive in certain factories. A special effort was made to analyze the fluctuation of transverse wall thickness uniformity. It was found that the wall thickness of each stand was accumulated in the original pass 50°~60° along the circumferential direction, which caused the formation of the inner hexagon defects and worsen. In view of this, this paper proposes a modified roll pass design method which uses the interactive technology of CAD graph curve and MATLAB equation. By means of decreasing the lateral curvature of roll pass contour curve to enlarge the contact length between the tube and groove, also the rolling process using the new pass system were simulated and analyzed. The results indicate that the design of such polygonal roll pass can be effective in improving the inner hexagon defects.

Analysis of Computational Model of Seamless Steel Pipe Rolling Contact Force

2018 ◽  
Vol 764 ◽  
pp. 376-382
Author(s):  
Lian Jin Li ◽  
Xing Han ◽  
Si Qi Liu
Keyword(s):  
Friction Coefficient ◽  
Yield Stress ◽  
Rolling Force ◽  
Rolling Process ◽  
Steel Tube ◽  
Rolling Contact ◽  
Wall Area ◽  
Seamless Steel Tube ◽  
Force Calculation ◽  
Seamless Steel

Due to the problems that the rolling force of seamless steel tube during tandem rolling process is affected by many factors, the calculation is complex and the accuracy is not enough. In order to improve the rolling force calculation accuracy of the tandem rolling mill, analyze the metal flow, stress distribution rules and cross section deformation characteristics during the rolling process of seamless steel tube, calculation of the rolling force was divided into the reduced-diameter area and the reduction of wall area, and a new calculation method was proposed, which concerns the rolling force in reduced-diameter area related to the material yield stress, friction coefficient and the crushing stress of the tube, while the rolling force in the reduction of wall area is only related to the material yield stress and the friction coefficient. The results show that the calculated rolling force is in agreement with the measured values with errors less than ±10%. The model satisfies the actual conditions and is applicable to engineering application.

Finite Element Simulation Analysis of Multi-Stands Three-Roller Cold Rolling Process for Double Metal Composite Seamless Steel Tube

2013 ◽  
Vol 470 ◽  
pp. 197-204 ◽  
Author(s):  
Xian Kang Wang ◽  
Jin Duo Ye ◽  
Xu Ma ◽  
Qian Qian Tian ◽  
Xue Li ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Cold Rolling ◽  
Rolling Process ◽  
Steel Tube ◽  
Metal Composite ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Seamless Steel Tube ◽  
Seamless Steel

The numerical simulation of the Y-type three-roller two stands cold rolling stainless steel/carbon steel double metal composite seamless steel tube process was conducted through the finite element analysis of the elastic-plastic by applying the MSC.MARC software. Based on the numerical simulation, the character of stress and strain distribution parameters during the Y-type three-roller two stands cold rolling were obtained by the finite element analysis, and acquired the section pass deformation figure. The distribution of the axial stress, circle stress and radial stress were drawn below the Y-type mill along the circle. The mechanism of the tube cold rolling process and the effect of the forming steel tube both the diameter and wall thickness accuracy were explained according to the stress distribution. The results of the research can be applied to the design of the technical parameters in the forming process.

Study on Wall Thickness Eccentricity of Seamless Steel Tube

2010 ◽  
Vol 148-149 ◽  
pp. 1071-1074 ◽  
Author(s):  
Qing Gong Lv ◽  
Long Zhou Peng ◽  
Jing Qing Zhu
Keyword(s):  
Cross Section ◽  
Wall Thickness ◽  
Steel Tube ◽  
Steel Tubes ◽  
Increase Wall Thickness ◽  
Factors Influencing ◽  
Feed Angle ◽  
Seamless Steel Tube ◽  
Seamless Steel Tubes ◽  
Seamless Steel

Wall thickness is measured by a micrometer on shells after piercing, hollows after rolling and tubes after stretch reducing in an Assel production line for seamless steel tubes. The characteristics of wall thickness eccentricity are exhibited, and the heredity and origin of wall thickness eccentricity are analyzed. Finally, the factors influencing wall thickness eccentricity are discussed. The results show that: (1) Wall thickness eccentricity originates from temperature eccentricity in cross section of round billets, comes into being on shells in piercing process, and is passed down to hollows and finally to tubes; (2) Bigger feed angle of piercing, smaller plug diameter and less stability of plug bar will increase wall thickness eccentricity, while complying to the influence of temperature eccentricity on round billets.

scholarly journals Mechanical analysis of enhancement in tensile performance of thin-walled circular tubes by internal support

2021 ◽  
Vol 13 (7) ◽  
pp. 168781402110327
Author(s):  
Yue Gao ◽  
Shao Fei ◽  
Xu Qian ◽  
Fan Pengxian ◽  
Gao Lei ◽  
...  
Keyword(s):  
Yield Strength ◽  
Ultimate Strength ◽  
Mechanical Performance ◽  
Mechanical Analysis ◽  
Steel Tube ◽  
Steel Tubes ◽  
Internal Support ◽  
Tensile Performance ◽  
Shrink Fitting ◽  
Thin Walled

Fillers can improve the tensile performance of ductile tubes. Mechanical analyses of tensile tubes with filler have generally focused on experimental and numerical studies on concrete-filled steel tube (CFST) components, while mechanical performance of tensile tubes with flexible supporting fillers has rarely been investigated. In the current research, we have proposed a “steel tube+pre-stressed flexible internal support” structure. Meanwhile, strengthening of tensile thin-walled tubes with internal supports was studied in terms of stress and deformation. The trends of yield strength and ultimate strength of tensile tubes were determined and calculation equations of yield strength and normal ultimate strength of tensile tubes with internal support were derived. Strengthening coefficient variations as functions of radius-thickness ratios of steel tubes and elastic moduli of internal supports as well the optimized internal support p corresponding to maximum increment of tensile performance of tubes were also determined. It was experimentally verified that the initial supporting pre-stress of internal support on steel tubes could be achieved by cold shrink fitting technique. Experimental results revealed that the developed composite structure significantly enhanced the mechanical performance, fracture toughness, and energy consumption characteristics of tensile tubes. Hence, the proposed structure was confirmed to have promising applications.

Prediction of Mechanical Properties of Seamless Steel Tubes Using Artificial Neural Networks

2020 ◽  
Vol 19 (04) ◽  
pp. 2050028
Author(s):  
Ramon Santos Correa ◽  
Patricia Teixeira Sampaio ◽  
Rafael Utsch Braga ◽  
Victor Alberto Lambertucci ◽  
Gustavo Matheus Almeida ◽  
...  
Keyword(s):  
Neural Network ◽  
Mechanical Properties ◽  
Sampling Rate ◽  
Steel Tube ◽  
Support Vector ◽  
Neural Network Models ◽  
Steel Tubes ◽  
Inference Models ◽  
Seamless Steel Tubes ◽  
Seamless Steel

A bottleneck of laboratory analysis in process industries including steelmaking plants is the low sampling rate. Inference models using only variables measured online have then been used to made such information available in advance. This study develops predictive models for key mechanical properties of seamless steel tubes, by strength, ultimate tensile strength and hardness. A plant in Brazil was used as the case study. The sample sizes of some steel tube families given namely, yield a particular property are discrepant and sometimes very small. To overcome this sample imbalance and lack of representativeness, committees of predictive neural network models based on bagging predictors, a type of ensemble method, were adopted. As a result, all steel families for all properties have been satisfactorily described showing the correlations between targets and model estimates close to 99%. These results were compared to multiple linear regression, support vector machine and a simpler neural network. Such information available in advance favors corrective actions before complete tube production mitigating rework costs in general.

Influence of Roll Speed Schedule on Transverse Wall Thickness Evenness of Shell Elongated by Mandrel Mill

2010 ◽  
Vol 654-656 ◽  
pp. 1311-1314 ◽  
Author(s):  
Sheng Zhi Li ◽  
Zhi Chao Zhang ◽  
Hai Yan Bao ◽  
Zhi Yang Zhou
Keyword(s):  
Wall Thickness ◽  
Rolling Process ◽  
Steel Tube ◽  
Transverse Wall ◽  
Data Reliability ◽  
Continuous Rolling ◽  
Roll Speed ◽  
Seamless Steel Tube ◽  
The Relationship ◽  
Seamless Steel

The seamless steel tube continuous rolling process with 8-stand full-floating mandrel is simulated with the aid of commercial FE code MSC. SuperForm. The relationship is analyzed between the distribution of the transverse wall-thickness and the speed schedule of the rollers. The result shows that the transverse evenness of the wall thickness of the tubes can be enhanced by optimizing the speed schedule. Furthermore, by adopting meliorated method to measure the wall-thickness of the shell, the error is reduced while data reliability is increased. When using the existing equipments (mandrel mill), it is an effective way to improve the transverse wall-thickness accuracy of the shell tube by adjusting the speed schedule. Compared with present roll speed schedule, the transverse wall-thickness accuracy can be increased by 10% for the rolling of elongated shell with 152.5mm in OD and 6mm in wall thickness tube under the 3# speed schedule put forward in this paper.

Explorative study of tandem skew rolling process for producing seamless steel tubes

2014 ◽  
Vol 214 (8) ◽  
pp. 1597-1604 ◽  
Author(s):  
Fu-jie Wang ◽  
Yuan-hua Shuang ◽  
Jian-hua Hu ◽  
Qing-hua Wang ◽  
Jing-chao Sun
Keyword(s):  
Rolling Process ◽  
Steel Tubes ◽  
Explorative Study ◽  
Seamless Steel Tubes ◽  
Skew Rolling ◽  
Seamless Steel

Research on Behavior of Circular Steel Tubes with Different Coating Subjected to Fire Load

2011 ◽  
Vol 243-249 ◽  
pp. 5227-5230
Author(s):  
Ming Zhou ◽  
Xin Tang Wang ◽  
Jie Yin ◽  
Zhi Guo Xie
Keyword(s):  
Outer Surface ◽  
Steel Tube ◽  
Test Results ◽  
Maximum Difference ◽  
Fire Response ◽  
Fire Load ◽  
Steel Tubes ◽  
Protective Material ◽  
Fire Experiment ◽  
Inner Surface

The fire experiment was conducted for three of circular steel tubes protected with two different gypsum fireproof panel and the steel tube without any protective material. The fire response temperature of surface of steel tubes was measured and the axial compressive bearing capacity of the specimens after fire were tested and analyzed. The test results show that gypsum fireproof panel has better fire protection characteristics. It is noted that the variation of temperatures of inner surface of gypsum fireproof panel under fire is consistent with the temperature of outer surface of the steel tube. The maximum difference of temperature between the outer surface of the tube and the furnace space is 150°C as the fire keeps stable for the steel tube without any protection. It is concluded that two of the specimens protected with gypsum fireproof panel have larger post-fire capacity, which means that the gypsum fireproof panel has better effect on fireproof of the steel tube under fire.

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