Investigations on Cryogenic Turning to Achieve Surface Hardening of Metastable Austenitic Steel AISI 347

2014 ◽  
Vol 1018 ◽  
pp. 153-160 ◽  
Author(s):  
Patrick Mayer ◽  
Benjamin Kirsch ◽  
Jan C. Aurich
Keyword(s):  
Phase Transformation ◽  
Surface Layer ◽  
Surface Hardening ◽  
Cryogenic Cooling ◽  
Austenitic Steels ◽  
Phase Content ◽  
Martensite Formation ◽  
Metastable Austenitic Steel ◽  
Steel Aisi ◽  
Cryogenic Turning

Metastable austenitic steels offer the opportunity of a surface hardening during machining due to a deformation induced martensite formation, substituting downstream hardening-processes. To maintain the necessary low process and workpiece temperatures for a phase transformation from austenite to martensite, cryogenic cooling using CO2-snow was examined in this study. The influence of workpiece diameter, coolant flow rate as well as pre-cooling and pre-surface hardening on the obtainable phase content of martensite in the surface layer was investigated.

scholarly journals Influence of surface morphology on the very high cycle fatigue behavior of metastable and stable austenitic Cr-Ni steels

2018 ◽  
Vol 165 ◽  
pp. 20008 ◽  
Author(s):  
Annika Boemke ◽  
Marek Smaga ◽  
Tilmann Beck
Keyword(s):  
Phase Transformation ◽  
Surface Layer ◽  
Surface Morphology ◽  
Austenitic Steel ◽  
Grain Refinement ◽  
Fatigue Testing ◽  
Testing Machine ◽  
Metastable Austenitic Steel ◽  
Steel Aisi ◽  
Cryogenic Turning

The present study investigates conventional and cryogenically turned specimens of metastable austenitic steel AISI 347 and stable austenitic steel AISI 904L in the VHCF regime. The cryogenic turning process includes cooling by CO2 snow and generates a surface layer on the specimens of metastable austenitic steel, which is characterized by a phase transformation from paramagnetic fcc - austenite to ferromagnetic bcc - martensite and grain refinement. The stable austenitic steel retains its purely austenitic structure after cryogenic turning, but also shows grain refinement in the surface layer. The specimens with different surface morphology were cyclically loaded at ambient temperature using an ultrasonic fatigue testing system developed and built at the authors’ institute. The testing machine operates at frequencies of approx. 20 kHz to achieve high numbers of load cycles within a reasonable time. To avoid self heating of the specimen, the tests were performed in pulse-pause mode. All specimens were tested with a load ratio of R = -1. During cyclic loading, the metastable austenitic steel partially transformed from paramagnetic fcc - austenite to ferromagnetic bcc - martensite, while no phase transformation could be detected in the stable austenitic steel.

A Finite Element Approach to Calculate Temperatures Arising During Cryogenic Turning of Metastable Austenitic Steel AISI 347

2018 ◽  
Author(s):  
Steven Becker ◽  
Hendrik Hotz ◽  
Benjamin Kirsch ◽  
Jan C. Aurich ◽  
Erik v. Harbou ◽  
...  
Keyword(s):  
Austenitic Steel ◽  
Cutting Speed ◽  
Cutting Parameters ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Metastable Austenitic Steel ◽  
System A ◽  
Element Approach ◽  
Steel Aisi ◽  
Cryogenic Turning

In this paper an inverse method is presented to evaluate the inner workpiece temperature distribution during cryogenic turning of metastable austenitic steel AISI 347 utilizing a FE representation of the process. Temperature data during the experiments is provided by thermocouples and a commercial thermo-graphy system. A constant cutting speed at two varying feeds are investigated. Inverse parameter verification by aligning simulated and experimental data in a least squares sense is achieved. A heat flux from tool to workpiece as well as heat transfer coefficients for forced convection by air and by carbon dioxide as cryogenic coolant are identified for each set of cutting parameters. Rigid body rotation in the model is considered applying convective time derivatives of the temperature field. Unphysical oscillations occurring in regions of high Péclet numbers are suppressed utilizing a streamline-upwind/Petrov-Galerkin scheme.

A Finite Element Approach to Calculate Temperatures Arising During Cryogenic Turning of Metastable Austenitic Steel AISI 347

2018 ◽  
Vol 140 (10) ◽  
Author(s):  
Steven Becker ◽  
Hendrik Hotz ◽  
Benjamin Kirsch ◽  
Jan C. Aurich ◽  
Erik V. Harbou ◽  
...  
Keyword(s):  
Austenitic Steel ◽  
Cutting Speed ◽  
Cutting Parameters ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Metastable Austenitic Steel ◽  
System A ◽  
Element Approach ◽  
Steel Aisi ◽  
Cryogenic Turning

In this paper, an inverse method is presented to evaluate the inner workpiece temperature distribution during cryogenic turning of metastable austenitic steel AISI 347 utilizing a FE representation of the process. Temperature data during the experiments are provided by thermocouples and a commercial thermography system. A constant cutting speed at two varying feeds is investigated. Inverse parameter verification by aligning simulated and experimental data in a least squares sense is achieved. A heat flux from tool to workpiece as well as heat transfer coefficients for forced convection by air and by carbon dioxide as cryogenic coolant are identified for each set of cutting parameters. Rigid body rotation in the model is considered applying convective time derivatives of the temperature field. Unphysical oscillations occurring in regions of high Péclet numbers are suppressed utilizing a streamline-upwind/Petrov–Galerkin scheme.

scholarly journals Surface layer hardening of metastable austenitic steel – Comparison of shot peening and cryogenic turning

2020 ◽  
Vol 9 (6) ◽  
pp. 16410-16422
Author(s):  
Hendrik Hotz ◽  
Benjamin Kirsch ◽  
Tong Zhu ◽  
Marek Smaga ◽  
Tilmann Beck ◽  
...  
Keyword(s):  
Surface Layer ◽  
Austenitic Steel ◽  
Shot Peening ◽  
Metastable Austenitic Steel ◽  
Surface Layer Hardening ◽  
Cryogenic Turning

scholarly journals Metastability and fatigue behavior of austenitic stainless steels

2018 ◽  
Vol 165 ◽  
pp. 04010 ◽  
Author(s):  
Marek Smaga ◽  
Annika Boemke ◽  
Tobias Daniel ◽  
Matthias W. Klein
Keyword(s):  
Phase Transformation ◽  
Strain Rate ◽  
Cyclic Deformation ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
Austenitic Steels ◽  
Threshold Temperature ◽  
Martensite Formation ◽  
Transformation Behavior ◽  
Phase Transformation Behavior

This study presents the results of a detailed investigation of metastability and susceptibility to deformation induced α’-martensite formation of several austenitic steels (AISI 304, AISI 321, AISI 348 and two batches from AISI 347) in the solution-annealed state. Besides conventional characterization of metastability by calculating stacking-fault energy and threshold temperature (designated as MS and Md30), the present work introduced a new method for determining susceptibility to α’-martensite formation. The method was based on dynamically applied local plastic deformation and non-destructive micro-magnetic measurement of α’-martensite content. The parameter Iξ was established, which correlated very well with the grade of α’-martensite formation during cyclic loading. The cyclic deformation and phase transformation behavior of cyclically loaded specimens from different metastable austenitic steels were investigated in total-strain and stress controlled fatigue tests with load ratio R = -1 at ambient temperature. The influence of the strain rate on the cyclic deformation and phase transformation behavior was also examined. During the fatigue tests, besides stress-strain hysteresis and temperature measurement, in situ micro-magnetic measurements were performed. Using the compressive measured data, the influence of plastic induced self-heating of the specimen and the strain rate on α’-martensite formation was analyzed.

Kryogenes Drehen von X6CrNiNb18-10*/Cryogenic turning of AISI 347 - Impact of the cutting edge radius on mechanical load and surface integrity

2018 ◽  
Vol 108 (01-02) ◽  
pp. 14-19
Author(s):  
H. Hotz ◽  
B. Kirsch ◽  
S. Gutwein ◽  
S. Becker ◽  
E. von Harbou ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Surface Hardening ◽  
Mechanical Load ◽  
Cutting Edge ◽  
Machining Process ◽  
Micro Hardness ◽  
Cutting Edge Radius ◽  
Metastable Austenitic Steel ◽  
Edge Radius ◽  
Cryogenic Turning

Metastabile austenitische Stähle bieten die Möglichkeit einer in den Zerspanprozess integrierten Randzonenverfestigung. Im Fachartikel wird zunächst der Einfluss des Schneidkantenradius auf die Prozesskräfte untersucht. Anschließend werden die daraus resultierenden Auswirkungen auf die verformungsinduzierte Martensitbildung in der Werkstückrandzone untersucht sowie die erzeugten Werkstücke hinsichtlich Mikrohärte und Rauheit verglichen.   Metastable austenitic steel enables direct surface hardening during the machining process. In this article, the influence of the cutting edge radius on process forces, as well as the effect on the martensitic phase transformation are investigated. The generated workpieces are examined with regard to micro hardness and surface roughness.

A Comparison Study of Surface Hardening by Grinding Versus Machining

2006 ◽  
Vol 304-305 ◽  
pp. 156-160 ◽  
Author(s):  
Zhan Qiang Liu ◽  
Xing Ai ◽  
Zhao Hui Wang
Keyword(s):  
Plastic Deformation ◽  
Phase Transformation ◽  
Surface Layer ◽  
Surface Hardening ◽  
White Layer ◽  
Comparison Study ◽  
Hardening Process ◽  
Grind Hardening ◽  
Principal Factors ◽  
Hardened Surface

This paper presents a comparison study of surface hardening by grinding versus machining. The technological, economical and ecological merits of machining hardening and grind-hardening process for steels are described. The mechanisms of machining hardening and grind-hardening of steels are investigated and compared. The phase transformation, plastic deformation and white layer generation are the principal factors contributing to the hardened surface layer by machining and grinding. The influences of the process parameters on the penetrated hardness are given for both grind-hardening and machining hardening operations. The future development trends of the grind-hardening and machining hardening are also presented.

scholarly journals Transient Finite Element Simulation of the Temperature Field during Cryogenic Turning of Metastable Austenitic Steel AISI 347

PAMM ◽  
2016 ◽  
Vol 16 (1) ◽  
pp. 303-304 ◽  
Author(s):  
Steven Becker ◽  
Patrick Mayer ◽  
Benjamin Kirsch ◽  
Jan C. Aurich ◽  
Erik v. Harbou ◽  
...  
Keyword(s):  
Finite Element ◽  
Temperature Field ◽  
Austenitic Steel ◽  
Finite Element Simulation ◽  
Metastable Austenitic Steel ◽  
Element Simulation ◽  
Steel Aisi ◽  
Cryogenic Turning
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