Influence of Dissipated Forming Energy on Flow Curves of Austenitic Stainless Steel

Steinheimer, Rainer; Engel, Bernd

doi:10.1063/1.3623676

Cited by 2 publications

(1 citation statement)

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“…Important factors, which are influencing the part temperature during forming process, are the forming speed, convective heat loss to air and thermal contact conductance to forming tools. Forming speed is known to increase temperature in non-isothermal tensile tests [4] due to lower heat loss to air and has a direct influence on mechanical properties [5]. Especially austenitic stainless steels are influenced by heat development due to suppression of strain-induced martensite formation and thereby so called TRIP-effect (TRansformation Induced Plasticty).…”

Section: Introductionmentioning

confidence: 99%

Thermal Influences on Deep Drawing Process of Ferritic and Metastable Austenitic Stainless Steels

Schmid

2013

AMR

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Sheet metal forming processes, in particular deep drawing processes, are highly influenced by occurrence of latent and friction heat. Especially when forming metastable austenitic stainless steels, strain-induced martensite formation is suppressed by higher temperatures and therefore influences the material behavior and so called TRIP-effect. This study gives an overview about thermal influences on the deep drawing forming process of metastable austenitic CrNi-steel 1.4301 in comparison with ferritic stainless steels such as 1.4016. Measurements on serial and evaluation tools were carried out to determine occurring temperatures within forming tools. Attention is paid to effects on tribological aspects such as behavior of lubricants at higher temperatures, influence of temperature development on the martensite formation, mechanical properties, forming limit curves as well as heat flow within the forming tools. Lubricants with different temperature stability were compared to each other with determination of friction coefficient in strip drawing tests. Martensite and temperature development during forming of material was measured in non-isothermal tensile tests approving a high dependency of martensite formation on temperature. Forming limit curves for temperatures determined from RT to 140°C for EN 1.4301 are showing high dependency of necking behavior especially under plain strain conditions. Determination of thermal contact conductance coefficients for process and tool relevant material combinations allows interpreting heat flow mechanisms in forming tools and improving forming process to higher robustness. Results of this paper can be used to individually set boundary conditions for thermo-mechanical coupled forming simulation of austenitic stainless steel and process layout of tool temperature control systems.

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Section: Introductionmentioning

confidence: 99%