Effect of Grain Size on Micro Ball Punch Deformation of SUS 304 Stainless Steel

2012 ◽  
Vol 579 ◽  
pp. 445-452 ◽  
Author(s):  
Chao Cheng Chang ◽  
Li Yi Lin
Keyword(s):  
Grain Size ◽  
Stainless Steel ◽  
304 Stainless Steel ◽  
Steel Sheets ◽  
High Production Rate ◽  
Micro Parts ◽  
Deformation Test ◽  
High Production ◽  
Different Diameters ◽  
Deformation Tests

Micro metal forming is widely interested due to its potential in manufacturing micro parts with low costs and high production rate as the demands of compact devices have been increasing in many fields. This study uses micro ball punch deformation tests to investigate the effect of grain size on the formability of SUS 304 stainless steel sheets. The study employed annealing treatments to change the grain size of the sheets. By using three punches in different diameters in associated with three dies having an inner diameter of 2 mm and different die radii, it was able to perform micro bulging tests and obtain the bulging depths which were used to assess the formability of the sheets. The study shows that the grain size does affect the depth of the deformed dome in the ball punch deformation test at the micro scale.

Modeling of Size Effects on the Flow Stress of Type 304 Stainless Steel and Application in Coining Process

2007 ◽  
Author(s):  
Gap-Yong Kim ◽  
Muammer Koc ◽  
Jun Ni
Keyword(s):  
Grain Size ◽  
Stainless Steel ◽  
Flow Stress ◽  
Size Effect ◽  
Size Effects ◽  
Specimen Size ◽  
304 Stainless Steel ◽  
Length Scales ◽  
Type 304 ◽  
Type 304 Stainless Steel

Application of microforming in various research areas has received much attention due to the increased demand for miniature metallic parts that require mass production. For the accurate analysis and design of microforming process, proper modeling of material behavior at the micro/meso-scale is necessary by considering the size effects. Two size effects are known to exist in metallic materials. One is the “grain size” effect, and the other is the “feature/specimen size” effect. This study investigated the “feature/specimen size” effect and introduced a scaling model which combined both feature/specimen and grain size effects. Predicted size effects were compared with experiments obtained from previous research and showed a very good agreement. The model was also applied to forming of micro-features by coining. A flow stress model for Type 304 stainless steel taking into consideration the effect of the grain and feature size was developed and implemented into a finite element simulation tool for an accurate numerical analysis. The scaling model offered a simple way to model the size effect down to length scales of a couple of grains and extended the use of continuum plasticity theories to micro/meso-length scales.

TENSILE AND FRACTURE BEHAVIOUR OF VERY THIN 304 STAINLESS STEEL SHEET

2016 ◽  
Vol 78 (6-9) ◽  
Author(s):  
Ammar Adil Al-Bakri ◽  
Zainuddin Sajuri ◽  
Ahmad Kamal Ariffin ◽  
Mohammed Abdul Razzaq ◽  
Mohd Salehudin Fafmin
Keyword(s):  
Stainless Steel ◽  
Cross Section ◽  
Steel Sheet ◽  
Rectangular Cross Section ◽  
Fracture Morphology ◽  
304 Stainless Steel ◽  
Stainless Steel Sheet ◽  
Steel Sheets ◽  
Ductile Mode ◽  
Mode Formation

Specimen with rectangular cross-section usually used to measure the tensile properties of materials. However, the specimen size and thickness may affect the results. In this study, tensile and fracture behaviours of very thin 304 stainless steel sheet were investigated. The thickness of the stainless steel sheets investigated were 100 and 300 µm. Tensile samples were cut into dumbbell-shaped of rectangular cross-section with same width for both thickness according to ASTM E8. The results showed that 100 µm thin steel sheet exhibited higher tensile strength with no clear evidence of yielding as compared to 300 µm sheet. The fracture morphology images observed by scanning electron microscopy revealed that both specimens fracture in ductile mode. Formation of dimples on the fracture surface could be recognized easily in 300 µm sample at higher magnification as compared to 100 µm sample.

scholarly journals Effect of Grain Size on the Friction-Induced Martensitic Transformation and Tribological Properties of 304 Austenite Stainless Steel

Metals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1246
Author(s):  
Bo Mao ◽  
Shuangjie Chu ◽  
Shuyang Wang
Keyword(s):  
Grain Size ◽  
Stainless Steel ◽  
Martensitic Transformation ◽  
Wear Rate ◽  
Tribological Properties ◽  
Friction And Wear ◽  
Wear Behavior ◽  
304 Stainless Steel ◽  
Dry Sliding ◽  
Transformation Behavior

Friction and wear performance of austenite stainless steels have been extensively studied and show a close relationship with the friction-induced martensitic transformation. However, how the grain size and associated friction-induced martensitic transformation behavior affect the tribological properties of austenite steels have not been systematically studied. In this work, dry sliding tests were performed on an AISI 304 stainless steel with a grain size ranging from 25 to 92 μm. The friction-induced surface morphology and microstructure evolution were characterized. Friction-induced martensitic transformation behavior, including martensite nucleation, martensite growth and martensite variant selection and its effect on the friction and wear behavior of the 304 stainless steel were analyzed. The results showed that both the surface coefficient of friction (COF) and the wear rate increase with the grain size. The COF was reduced three times and wear rate was reduced by 30% as the grain size decreased from 92 to 25 μm. A possible mechanism is proposed to account for the effect of grain size on the tribological behavior. It is discussed that austenite steel with refined grain size tends to suppress the amount of friction-induced martensitic transformed and significantly alleviates both the plowing and adhesive effect during dry sliding.

scholarly journals Experimental and Numerical Investigations on Microcoining of Stainless Steel 304

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Gap-Yong Kim ◽  
Muammer Koç ◽  
Jun Ni
Keyword(s):  
Grain Size ◽  
Stainless Steel ◽  
Bulk Material ◽  
High Strength ◽  
304 Stainless Steel ◽  
Feature Size ◽  
Stainless Steel 304 ◽  
Metallic Parts ◽  
Type 304 ◽  
Type 304 Stainless Steel

Increasing demands for miniature metallic parts have driven the application of microforming in various industries. Only a limited amount of research is, however, available on the forming of miniature features in high strength materials. This study investigated the forming of microfeatures in Type 304 stainless steel by using the coining process. Experimental work was performed to study the effects of workpiece thickness, preform shape, grain size, and feature size on the formation of features ranging from 320μmto800μm. It was found that certain preform shapes enhance feature formation by allowing a favorable flow of the bulk material. In addition, a flow stress model for Type 304 stainless steel that took into consideration the effects of the grain and feature sizes was developed to accurately model and better understand the coining process. Weakening of the material, as the grain size increased at the miniature scale, was explained by the Hall–Petch relationship and the feature size effect.

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