退火温度对TWIP钢组织性能和氢致脆性的影响
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摘要
采用电化学结合低应变速率拉伸实验(SSRT)的方法和OM、SEM等手段研究了退火温度对Fe-18Mn-0.6C TWIP钢充氢条件下力学性能和变形行为的影响,并探讨了各类微观组织结构对氢致脆性的作用。结果表明,TWIP钢晶粒尺寸随退火温度的升高逐渐增大,700℃退火板晶界处容易观察到(Fe, Mn)3C渗碳体。900℃退火获得的中等尺寸均匀晶粒的TWIP钢具有最高的强塑积。在电化学充氢和SSRT同时进行下,TWIP钢的强度和塑性大幅下降,随退火温度的升高,强塑积损失率(R)呈增大趋势。高温退火得到的大尺寸晶粒在变形中更容易产生形变孪晶,孪晶/孪晶交叉位置和孪晶/晶界交叉位置是氢致裂纹的主要来源。尽管相对低温退火得到大尺寸晶粒和界面处层错能(SFE)变化使TWIP钢在变形中不容易产生形变孪晶,但其局部粗大的碳化物与形变孪晶间产生的应力集中处极易形成空位,演化成裂纹源,使相对低温退火的TWIP钢本身塑性不高。低于800℃退火对TWIP钢提高氢脆抵抗力没有明显作用。
TWIP steel as the representative of advanced high strength steel(AHSS) has a bright future in market and application owing to its excellent strength and ductility. Hydrogen embrittlement(HE)as a difficult problem of TWIP steel, researches on solving it mainly focus on alloying, few effort has been made on the mechanism of improving HE resistance by process adjustment and microstructure optimization. In this work, electrochemically combined with slow strain rate tensile test(SSRT) and OM, SEM have been used to study the effect of annealing temperature on mechanical property and deformation behavior of a Fe-18 Mn-0.6 C(mass fraction, %) twinning-induced plasticity(TWIP) steel, and also the influence of various microstructures on HE were discussed. The results showed that the grain size of TWIP steel increased with the increasing annealing temperature. In 700 ℃ annealed sheet, grain boundary(Fe,Mn)3 C cementite was obvious. TWIP steel with uniform medium-sized grains by 900 ℃ annealing had the highest strength-ductility balance. After SSRT under ongoing hydrogen charging, strength and plasticity reduced significantly. The strength-ductility balance loss rate(R) showed a tendency of increasing with the increasing annealing temperature. Deformation twins were more likely to be produced in large-sized grains by high temperature annealing. The junctions of twin/twin and twin/grain boundary were the main sources of hydrogen induced cracks. Although relatively low temperature annealing resulted in fine grains and the change of stacking fault energy(SFE) along grain boundary, deformation twins were not easily formed. But it was very vulnerable to generate vacancies where the stress concentrated between the local coarse carbides and deformation twins, then evolved into crack sources. As a result, the plasticity of TWIP steel itself was not high when annealed at a relatively low temperature. It had no apparent effect on improving HE resistance for TWIP steel annealed below 800 ℃.
TWIP steel as the representative of advanced high strength steel(AHSS) has a bright future in market and application owing to its excellent strength and ductility. Hydrogen embrittlement(HE)as a difficult problem of TWIP steel, researches on solving it mainly focus on alloying, few effort has been made on the mechanism of improving HE resistance by process adjustment and microstructure optimization. In this work, electrochemically combined with slow strain rate tensile test(SSRT) and OM, SEM have been used to study the effect of annealing temperature on mechanical property and deformation behavior of a Fe-18 Mn-0.6 C(mass fraction, %) twinning-induced plasticity(TWIP) steel, and also the influence of various microstructures on HE were discussed. The results showed that the grain size of TWIP steel increased with the increasing annealing temperature. In 700 ℃ annealed sheet, grain boundary(Fe,Mn)3 C cementite was obvious. TWIP steel with uniform medium-sized grains by 900 ℃ annealing had the highest strength-ductility balance. After SSRT under ongoing hydrogen charging, strength and plasticity reduced significantly. The strength-ductility balance loss rate(R) showed a tendency of increasing with the increasing annealing temperature. Deformation twins were more likely to be produced in large-sized grains by high temperature annealing. The junctions of twin/twin and twin/grain boundary were the main sources of hydrogen induced cracks. Although relatively low temperature annealing resulted in fine grains and the change of stacking fault energy(SFE) along grain boundary, deformation twins were not easily formed. But it was very vulnerable to generate vacancies where the stress concentrated between the local coarse carbides and deformation twins, then evolved into crack sources. As a result, the plasticity of TWIP steel itself was not high when annealed at a relatively low temperature. It had no apparent effect on improving HE resistance for TWIP steel annealed below 800 ℃.
引文
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[2]Hong S,Shin S Y,Kim H S,et al.Effects of inclusions on delayed fracture properties of three twinning induced plasticity(TWIP)steels[J].Metall.Mater.Trans.,2013,44A:776
[3]van Tol R T,Zhao L,Bracke L,et al.Investigation of the delayed fracture phenomenon in deep-drawn austenitic manganese-based twinning-induced plasticity steels[J].Metall.Mater.Trans.,2013,44A:4654
[4]Koyama M,Akiyama E,Tsuzaki K.Hydrogen embrittlement in a Fe-Mn-C ternary twinning-induced plasticity steel[J].Corros.Sci.,2012,54:1
[5]Koyama M,Akiyama E,Lee Y K,et al.Overview of hydrogen embrittlement in high-Mn steels[J].Int.J.Hydrogen Energy,2017,42:12706
[6]Ronevich J A,Kim S K,Speer J G,et al.Hydrogen effects on cathodically charged twinning-induced plasticity steel[J].Scr.Mater.,2012,66:956
[7]Chun Y S,Park K T,Lee C S.Delayed static failure of twinninginduced plasticity steels[J].Scr.Mater.,2012,66:960
[8]Koyama M,Akiyama E,Tsuzaki K.Hydrogen-assisted failure in a twinning-induced plasticity steel studied under in situ hydrogen charging by electron channeling contrast imaging[J].Acta Mater.,2013,61:4607
[9]Wang M Q,Akiyama E,Tsuzaki K.Hydrogen degradation of a boron-bearing steel with 1050 and 1300 MPa strength levels[J].Scr.Mater.,2005,52:403
[10]Toribio J,Kharin V,Lorenzo M,et al.Role of drawing-induced residual stresses and strains in the hydrogen embrittlement susceptibility of prestressing steels[J].Corros.Sci.,2011,53:3346
[11]Enos D G,Scully J R.A critical-strain criterion for hydrogen embrittlement of cold-drawn,ultrafine pearlitic steel[J].Metall.Mater.Trans.,2002,33A:1151
[12]Wang M Q,Akiyama E,Tsuzaki K.Effect of hydrogen on the fracture behavior of high strength steel during slow strain rate test[J].Corros.Sci.,2007,49:4081
[13]Barnoush A,Vehoff H.Recent developments in the study of hydrogen embrittlement:Hydrogen effect on dislocation nucleation[J].Acta Mater.,2010,58:5274
[14]Takagi S,Toji Y,Yoshino M,et al.Hydrogen embrittlement resistance evaluation of ultra high strength steel sheets for automobiles[J].ISIJ Int.,2012,52:316
[15]Song E J,Bhadeshia H K D H,Suh D W.Interaction of aluminium with hydrogen in twinning-induced plasticity steel[J].Scr.Mater.,2014,87:9
[16]DieudonnéT,Marchetti L,Wery M,et al.Role of copper and aluminum additions on the hydrogen embrittlement susceptibility of austenitic Fe-Mn-C TWIP steels[J].Corros.Sci.,2014,82:218
[17]Malard B,Remy B,Scott C,et al.Hydrogen trapping by VC precipitates and structural defects in a high strength Fe-Mn-C steel studied by small-angle neutron scattering[J].Mater.Sci.Eng.,2012,A536:110
[18]Zhao Y Y,Wang J F,Zhou S,et al.Effects of rare earth addition on microstructure and mechanical properties of a Fe-15Mn-1.5Al-0.6C TWIP steel[J].Mater.Sci.Eng.,2014,A608:106
[19]Dini G,Najafizadeh A,Ueji R,et al.Tensile deformation behavior of high manganese austenitic steel:The role of grain size[J].Mater.Des.,2010,31:3395
[20]Chen L,Kim H S,Kim S K,et al.Localized deformation due to Portevin-Le Chatelier effect in 18Mn-0.6C TWIP austenitic steel[J].ISIJ Int.,2007,47:1804
[21]Guo P C,Qian L H,Meng J Y,et al.Monotonic tension and tension-compres-sion cyclic deformation behaviors of high manganese austenitic TWIP steel[J].Acta Metall.Sin.,2014,50:415(郭鹏程,钱立和,孟江英等.高锰奥氏体TWIP钢的单向拉伸与拉压循环变形行为[J].金属学报,2014,50:415)
[22]El-Danaf E,Kalidindi S R,Doherty R D.Influence of deformation path on the strain hardening behavior and microstructure evolution in low SFE FCC metals[J].Int.J.Plast.,2001,17:1245
[23]Ueji R,Tsuchida N,Terada D,et al.Tensile properties and twinning behavior of high manganese austenitic steel with fine-grained structure[J].Scr.Mater.,2008,59:963
[24]Park I J,Lee S M,Jeon H H,et al.The advantage of grain refinement in the hydrogen embrittlement of Fe-18Mn-0.6C twinninginduced plasticity steel[J].Corros.Sci.,2015,93:63
[25]Oudriss A,Creus J,Bouhattate J,et al.Grain size and grain-boundary effects on diffusion and trapping of hydrogen in pure nickel[J].Acta Mater.,2012,60:6814
[26]Oudriss A,Creus J,Bouhattate J,et al.The diffusion and trapping of hydrogen along the grain boundaries in polycrystalline nickel[J].Scr.Mater.,2012,66:37
[27]Du Y A,Ismer L,Rogal J,et al.First-principles study on the interaction of H interstitials with grain boundaries inα-andγ-Fe[J].Phys.Rev.,2011,84B:144121
[28]Hutchinson B,Ridley N.On dislocation accumulation and work hardening in Hadfield steel[J].Scr.Mater.,2006,55:299
[29]Idrissi H,Renard K,Ryelandt L,et al.On the mechanism of twin formation in Fe-Mn-C TWIP steels[J].Acta Mater.,2010,58:2464
[30]Hermida J D,Roviglione A.Stacking fault energy decrease in austenitic stainless steels induced by hydrogen pairs formation[J].Scr.Mater.,1998,39:1145
[31]Steinmetz D R,Japel T,Wietbrock B,et al.Revealing the strainhardening behavior of twinning-induced plasticity steels:Theory,simulations,experiments[J].Acta Mater.,2013,61:494
[32]Saeed-Akbari A,Mosecker L,Schwedt A,et al.Characterization and prediction of flow behavior in high-manganese twinning induced plasticity steels:Part I.Mechanism maps and work-hardening behavior[J].Metall.Mater.Trans.,2012,43A:1688
[33]Idrissi H,Renard K,Schryvers D,et al.On the relationship between the twin internal structure and the work-hardening rate of TWIP steels[J].Scr Mater.,2010,63:961
[34]Sevillano J G.Geometrically necessary twins and their associated size effects[J].Scr.Mater.,2008,59:135
[35]Hong S,Lee J,Lee B J,et al.Effects of intergranular carbide precipitation on delayed fracture behavior in three twinning induced plasticity(TWIP)steels[J].Mater.Sci.Eng.,2013,A587:85
[36]Herbig M,Kuzmina M,Haase C,et al.Grain boundary segregation in Fe-Mn-C twinning-induced plasticity steels studied by correlative electron backscatter diffraction and atom probe tomography[J].Acta Mater.,2015,83:37
[37]Hickel T,Sandl?bes S,Marceau R K W,et al.Impact of nanodiffusion on the stacking fault energy in high-strength steels[J].Acta Mater.,2014,75:147
[38]Mahajan S,Chin G Y.Formation of deformation twins in f.c.c.crystals[J].Acta Metall.,1973,21:1353
[39]Gutierrez-Urrutia I,Raabe D.Influence of Al content and precipitation state on the mechanical behavior of austenitic high-Mn lowdensity steels[J].Scr.Mater.,2013,68:343
[2]Hong S,Shin S Y,Kim H S,et al.Effects of inclusions on delayed fracture properties of three twinning induced plasticity(TWIP)steels[J].Metall.Mater.Trans.,2013,44A:776
[3]van Tol R T,Zhao L,Bracke L,et al.Investigation of the delayed fracture phenomenon in deep-drawn austenitic manganese-based twinning-induced plasticity steels[J].Metall.Mater.Trans.,2013,44A:4654
[4]Koyama M,Akiyama E,Tsuzaki K.Hydrogen embrittlement in a Fe-Mn-C ternary twinning-induced plasticity steel[J].Corros.Sci.,2012,54:1
[5]Koyama M,Akiyama E,Lee Y K,et al.Overview of hydrogen embrittlement in high-Mn steels[J].Int.J.Hydrogen Energy,2017,42:12706
[6]Ronevich J A,Kim S K,Speer J G,et al.Hydrogen effects on cathodically charged twinning-induced plasticity steel[J].Scr.Mater.,2012,66:956
[7]Chun Y S,Park K T,Lee C S.Delayed static failure of twinninginduced plasticity steels[J].Scr.Mater.,2012,66:960
[8]Koyama M,Akiyama E,Tsuzaki K.Hydrogen-assisted failure in a twinning-induced plasticity steel studied under in situ hydrogen charging by electron channeling contrast imaging[J].Acta Mater.,2013,61:4607
[9]Wang M Q,Akiyama E,Tsuzaki K.Hydrogen degradation of a boron-bearing steel with 1050 and 1300 MPa strength levels[J].Scr.Mater.,2005,52:403
[10]Toribio J,Kharin V,Lorenzo M,et al.Role of drawing-induced residual stresses and strains in the hydrogen embrittlement susceptibility of prestressing steels[J].Corros.Sci.,2011,53:3346
[11]Enos D G,Scully J R.A critical-strain criterion for hydrogen embrittlement of cold-drawn,ultrafine pearlitic steel[J].Metall.Mater.Trans.,2002,33A:1151
[12]Wang M Q,Akiyama E,Tsuzaki K.Effect of hydrogen on the fracture behavior of high strength steel during slow strain rate test[J].Corros.Sci.,2007,49:4081
[13]Barnoush A,Vehoff H.Recent developments in the study of hydrogen embrittlement:Hydrogen effect on dislocation nucleation[J].Acta Mater.,2010,58:5274
[14]Takagi S,Toji Y,Yoshino M,et al.Hydrogen embrittlement resistance evaluation of ultra high strength steel sheets for automobiles[J].ISIJ Int.,2012,52:316
[15]Song E J,Bhadeshia H K D H,Suh D W.Interaction of aluminium with hydrogen in twinning-induced plasticity steel[J].Scr.Mater.,2014,87:9
[16]DieudonnéT,Marchetti L,Wery M,et al.Role of copper and aluminum additions on the hydrogen embrittlement susceptibility of austenitic Fe-Mn-C TWIP steels[J].Corros.Sci.,2014,82:218
[17]Malard B,Remy B,Scott C,et al.Hydrogen trapping by VC precipitates and structural defects in a high strength Fe-Mn-C steel studied by small-angle neutron scattering[J].Mater.Sci.Eng.,2012,A536:110
[18]Zhao Y Y,Wang J F,Zhou S,et al.Effects of rare earth addition on microstructure and mechanical properties of a Fe-15Mn-1.5Al-0.6C TWIP steel[J].Mater.Sci.Eng.,2014,A608:106
[19]Dini G,Najafizadeh A,Ueji R,et al.Tensile deformation behavior of high manganese austenitic steel:The role of grain size[J].Mater.Des.,2010,31:3395
[20]Chen L,Kim H S,Kim S K,et al.Localized deformation due to Portevin-Le Chatelier effect in 18Mn-0.6C TWIP austenitic steel[J].ISIJ Int.,2007,47:1804
[21]Guo P C,Qian L H,Meng J Y,et al.Monotonic tension and tension-compres-sion cyclic deformation behaviors of high manganese austenitic TWIP steel[J].Acta Metall.Sin.,2014,50:415(郭鹏程,钱立和,孟江英等.高锰奥氏体TWIP钢的单向拉伸与拉压循环变形行为[J].金属学报,2014,50:415)
[22]El-Danaf E,Kalidindi S R,Doherty R D.Influence of deformation path on the strain hardening behavior and microstructure evolution in low SFE FCC metals[J].Int.J.Plast.,2001,17:1245
[23]Ueji R,Tsuchida N,Terada D,et al.Tensile properties and twinning behavior of high manganese austenitic steel with fine-grained structure[J].Scr.Mater.,2008,59:963
[24]Park I J,Lee S M,Jeon H H,et al.The advantage of grain refinement in the hydrogen embrittlement of Fe-18Mn-0.6C twinninginduced plasticity steel[J].Corros.Sci.,2015,93:63
[25]Oudriss A,Creus J,Bouhattate J,et al.Grain size and grain-boundary effects on diffusion and trapping of hydrogen in pure nickel[J].Acta Mater.,2012,60:6814
[26]Oudriss A,Creus J,Bouhattate J,et al.The diffusion and trapping of hydrogen along the grain boundaries in polycrystalline nickel[J].Scr.Mater.,2012,66:37
[27]Du Y A,Ismer L,Rogal J,et al.First-principles study on the interaction of H interstitials with grain boundaries inα-andγ-Fe[J].Phys.Rev.,2011,84B:144121
[28]Hutchinson B,Ridley N.On dislocation accumulation and work hardening in Hadfield steel[J].Scr.Mater.,2006,55:299
[29]Idrissi H,Renard K,Ryelandt L,et al.On the mechanism of twin formation in Fe-Mn-C TWIP steels[J].Acta Mater.,2010,58:2464
[30]Hermida J D,Roviglione A.Stacking fault energy decrease in austenitic stainless steels induced by hydrogen pairs formation[J].Scr.Mater.,1998,39:1145
[31]Steinmetz D R,Japel T,Wietbrock B,et al.Revealing the strainhardening behavior of twinning-induced plasticity steels:Theory,simulations,experiments[J].Acta Mater.,2013,61:494
[32]Saeed-Akbari A,Mosecker L,Schwedt A,et al.Characterization and prediction of flow behavior in high-manganese twinning induced plasticity steels:Part I.Mechanism maps and work-hardening behavior[J].Metall.Mater.Trans.,2012,43A:1688
[33]Idrissi H,Renard K,Schryvers D,et al.On the relationship between the twin internal structure and the work-hardening rate of TWIP steels[J].Scr Mater.,2010,63:961
[34]Sevillano J G.Geometrically necessary twins and their associated size effects[J].Scr.Mater.,2008,59:135
[35]Hong S,Lee J,Lee B J,et al.Effects of intergranular carbide precipitation on delayed fracture behavior in three twinning induced plasticity(TWIP)steels[J].Mater.Sci.Eng.,2013,A587:85
[36]Herbig M,Kuzmina M,Haase C,et al.Grain boundary segregation in Fe-Mn-C twinning-induced plasticity steels studied by correlative electron backscatter diffraction and atom probe tomography[J].Acta Mater.,2015,83:37
[37]Hickel T,Sandl?bes S,Marceau R K W,et al.Impact of nanodiffusion on the stacking fault energy in high-strength steels[J].Acta Mater.,2014,75:147
[38]Mahajan S,Chin G Y.Formation of deformation twins in f.c.c.crystals[J].Acta Metall.,1973,21:1353
[39]Gutierrez-Urrutia I,Raabe D.Influence of Al content and precipitation state on the mechanical behavior of austenitic high-Mn lowdensity steels[J].Scr.Mater.,2013,68:343