An Experimental Investigation of Surface Pit Evolution During Cold-Rolling or Drawing of Stainless Steel Strip

2000 ◽  
Vol 123 (1) ◽  
pp. 1-7 ◽  
Author(s):  
R. Ahmed ◽  
M. P. F. Sutcliffe
Keyword(s):  
Experimental Investigation ◽  
Stainless Steel ◽  
Hydrodynamic Lubrication ◽  
Steel Strip ◽  
Similar Rate ◽  
Steel Strips ◽  
Strip Drawing ◽  
Hot Band ◽  
Cold Rolled

This paper presents an experimental investigation of the mechanisms of pit elimination in strip drawing and rolling of stainless steel strips. Strip drawing tests with artificial indents confirm the role of micro-plasto-hydrodynamic lubrication (MPHL) in allowing pits to be reduced in size and depth. The similarity of results for two oils, which differ in viscosity by a factor of 10, is attributed to the fact that oil is drawn out of the pits rather easily, so that the behavior tends to the unlubricated case. Similar behavior is observed for strip drawing of shot blast white hot band. For much smoother bright anneal strip, it is suggested that the presence of an oil film in the unpitted region prevents generation of pressure differences between the pits and the unpitted regions. A comparison of strip-drawn and cold-rolled stainless steel samples show that the change in pit area and Rq roughness varies with overall reduction in a remarkably similar way. The reason for such similar behavior is attributed to the absence of hydrodynamic action in preventing pit elimination, albeit for opposite reasons. The similar rate of pit evolution in both cases confirms the usefulness of the strip drawing rig as a tool to model the change of surface topography during rolling, as long as care is taken in matching the regimes of lubrication.

scholarly journals Modeling of Micro-Pit Evolution in Rolling or Strip-Drawing

2000 ◽  
Vol 123 (4) ◽  
pp. 791-798 ◽  
Author(s):  
M. P. F. Sutcliffe ◽  
H. R. Le ◽  
R. Ahmed
Keyword(s):  
Hydrodynamic Lubrication ◽  
Steel Strip ◽  
Viscosity Coefficient ◽  
Sliding Speed ◽  
Dimensional Group ◽  
Theoretical Predictions ◽  
Strip Drawing ◽  
Measured Change ◽  
Cold Rolled ◽  
Lubricant Viscosity

The micro-plasto-hydrodynamic lubrication (MPHL) model of pit evolution is extended to account for the variation of sliding speed and strain rate in rolling and drawing processes. Results show that all of the following factors are important: pit angle, lubricant viscosity and pressure viscosity coefficient, material yield stress and sliding speed. Theoretical predictions for the change in pit area during the deformation process are well correlated by a non-dimensional group of these parameters. The model agrees reasonably with the measured change in pit volume and area from drawing experiments on cold rolled stainless steel strip containing both artificial and stochastic roughness.

Evolution of Surface Pits on Stainless Steel Strip in Cold Rolling and Strip Drawing

2003 ◽  
Vol 125 (2) ◽  
pp. 384-390 ◽  
Author(s):  
H. R. Le ◽  
M. P. F. Sutcliffe
Keyword(s):  
Stainless Steel ◽  
Cold Rolling ◽  
Hydrodynamic Lubrication ◽  
Steel Strip ◽  
Theoretical Models ◽  
Finite Depth ◽  
Work Zone ◽  
Oil Film ◽  
Strip Drawing ◽  
Inlet Zone

Theoretical models are presented for describing the evolution of pits in the inlet and work zone during cold rolling and strip drawing of shot-blast stainless steel under ‘mixed’ lubrication. Results shows that the rough shot-blast surface is flattened rapidly in a short inlet zone, thereby entrapping the lubricant in surface pits. The subsequent evolution of these surface pits in the work zone can be explained by micro-plasto-hydrodynamic-lubrication (MPHL) models described previously. A development of these models is presented which takes into account the effects of the oil film entrained in the inlet, an oil film penetrating from adjacent pits and the finite depth of the pits. The role of an inlet oil film and penetrating MPHL oil film is to limit the potential reduction of pit size. Lubrication regime maps are constructed which describe the evolution of the surface pits for a range of pit geometries. Results explain the experimental observation that some pits survive even after a multi-pass schedule. Predictions of the pit area show good agreement with measurements on samples obtained in strip drawing or rolled under industrial conditions.

Analysis of ZDDP Films on Sticking Defects by FEM during Hot Rolling of Ferritic Stainless Steel Strips

2016 ◽  
Vol 846 ◽  
pp. 96-101
Author(s):  
Liang Hao ◽  
Zheng Yi Jiang ◽  
Dian Yao Gong ◽  
Dong Bin Wei ◽  
Xia Wei Cheng ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Stainless Steel ◽  
Ferritic Stainless Steel ◽  
Hot Rolling ◽  
Steel Strip ◽  
Crack Size ◽  
Surface Characterisation ◽  
Fem Model ◽  
Steel Strips ◽  
Simulation Results

The aim of this study is to understand the effect of zinc dialkyl dithio phosphate (ZDDP) films on sticking defects during the hot rolling of ferritic stainless steel strips. The surface characterisation and crack propagation are very important for the sticking defects of ferritic stainless steel strip. A finite element method (FEM) model is constructed with different crack size ratios, in which the profile of the strip roughness and ZDDP films are taken into consideration. Simulation results show that the widths of cracks tend to be reduced with the introduction of ZDDP films, improving the sticking defects, which is confirmed by the hot rolling trials.

Effect of the Rolling Draughts on the Evolution of Textures and Microstructures in 17.5 Cr-1.1 Mo Ferritic Stainless Steel Sheet

2005 ◽  
Vol 495-497 ◽  
pp. 363-368
Author(s):  
Soo Ho Park ◽  
Hyung Gu Kang ◽  
Yong Deuk Lee ◽  
Jae Chul Lee ◽  
Moo Young Huh
Keyword(s):  
Stainless Steel ◽  
Ferritic Stainless Steel ◽  
Steel Sheet ◽  
Recrystallization Annealing ◽  
Reduction Degree ◽  
Stainless Steel Sheet ◽  
Steel Sheets ◽  
Hot Band ◽  
Cold Rolled ◽  
Number Of Passes

In order to investigate the effect of the reduction degree per rolling pass on the evolution of recrystallization textures and microstructures, the hot band of 17.5 Cr-1.1 Mo ferritic stainless steel sheets were cold rolled with lubrication according to two processing routes, by which different reduction degrees per pass were introduced. Rolling with a large number of passes led to the formation of fairly homogeneous rolling textures at all through-thickness positions. In contrast, cold rolling with large draughts resulted in pronounced texture gradients along the thickness direction. After recrystallization annealing, the texture maximum was obtained at {334}<483> in all samples regardless of the rolling routes and thickness layers. During subsequent annealing, recrystallization was observed to be faster in those grains with {111}<uvw> orientations, while it was retarded in grains having orientations close to {001}<110>.

scholarly journals Identification of surface features on cold-rolled stainless steel strip

Wear ◽  
2000 ◽  
Vol 244 (1-2) ◽  
pp. 60-70 ◽  
Author(s):  
R Ahmed ◽  
M.P.F Sutcliffe
Keyword(s):  
Stainless Steel ◽  
Steel Strip ◽  
Surface Features ◽  
Cold Rolled

Application of Recrystallization Texture Evolution Model to Predict Plastic Formability in Steel Strips

2014 ◽  
Vol 783-786 ◽  
pp. 1954-1960
Author(s):  
Toshiharu Morimoto ◽  
Y. Fuyuki ◽  
A. Yanagida ◽  
Jun Yanagimoto
Keyword(s):  
Recrystallization Texture ◽  
Texture Evolution ◽  
Steel Strip ◽  
Rolling Texture ◽  
Interstitial Free ◽  
If Steel ◽  
Taylor Model ◽  
Steel Strips ◽  
Cold Rolled ◽  
Hot Rolled

T.M.C.P.(Thermo Mechanical Control Processing) has been widely used to improveplastic formability in steel strips. We have produced interstitial free steel(IF steel) strips and ferriticstainless-steel strips through T.M.C.P. rolling method. Optimizing conditions of hot rolling, hotrolled annealing, cold rolling and cold rolled annealing, we developed texture prediction model. Wecan predict rolling texture accurately using the conventional Taylor model. Moreover, we preciselypredict recrystallization texture classifying the total number of microscopic􀀁 slips which arecalculated using the Taylor model. We consider that these calculated results provednucleation-oriented model and two types of recrystallization and grain growth mechanisms exit inour studies. One mechanism is that grains which had the small total number of microscopic slips arepreferred orientation for the hot rolled and annealed ferritic stainless-steel strip. The othermechanism is that grains which had the high total number of microscopic slips are preferredorientation for the cold rolled and annealed IF steel strip.

Effect of micro-defects on the surface brightness of cold-rolled stainless-steel strip

1997 ◽  
Vol 69 (1-3) ◽  
pp. 106-111 ◽  
Author(s):  
Kazuhito Kenmochi ◽  
Ikuo Yarita ◽  
Hideo Abe ◽  
Akihiko Fukuhara ◽  
Tomio Komatu ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Surface Brightness ◽  
Steel Strip ◽  
Cold Rolled

Heating Effects in the Drawing of Wire and Strip Under Hydrodynamic Lubrication Conditions

1996 ◽  
Vol 118 (4) ◽  
pp. 628-638 ◽  
Author(s):  
D. A. Lucca ◽  
R. N. Wright
Keyword(s):  
High Speed ◽  
Hydrodynamic Lubrication ◽  
Lubricant Film ◽  
Strip Surface ◽  
Heating Effects ◽  
Strip Drawing ◽  
Dimensional Parameters ◽  
Lubrication Conditions ◽  
Lubricant Viscosity

The use of high metal processing speeds to meet the demands for increased productivity has focused attention on the pronounced heating of tooling and workpiece which occurs under these conditions. In the present study, heating under hydrodynamic conditions in wire and strip drawing is addressed by considering a two-dimensional representation of the tool-lubricant-workpiece interface. An analytical formulation is presented for prediction of the resultant temperatures. The model considers deformation heating in the strip, lubricant viscosity to be a function of temperature and pressure, and matches the heat flux at the strip-lubricant boundary. Convection of heat in the lubricant film is considered. The model is constructed in terms of the governing non-dimensional parameters and solved by a Crank-Nicolson finite difference technique. By comparison with solutions which do not consider convection, it is found that convection only begins to play a role in the resulting temperatures when the Graetz number U0h02/αLl is greater than 0.4. For the high speed drawing of aluminum with mineral oil used as a lubricant, the model predicts a monotonic increase in mean lubricant temperatures from 366 K to 404 K over a range of initial strip velocities of 20.3 m/s to 50.8 m/s. The maximum strip surface temperature is predicted to monotonically decrease from 345 K to 335 K over this range of strip velocities. The ratio (kLρLcpL/ksρscpS)1/2 is shown to be important in determining the relative temperatures of lubricant and strip. Results are compared to those metalworking analyses which do not consider the role of the lubricant film.

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