This work investigated the gradient microstructure evolution and tensile property of LPBF fabricated 15-5 precipitation hardening stainless steel in post-process direct ageing(DA)and solution treating&ageing(STA)....This work investigated the gradient microstructure evolution and tensile property of LPBF fabricated 15-5 precipitation hardening stainless steel in post-process direct ageing(DA)and solution treating&ageing(STA).The varied microstructures for austenite and small-sized oxide inclusions at different sample heights in the as-built(AB)condition was generally preserved after DA treatment.However,austenite was almost disappeared,and oxide particle grew significantly after the STA treatment.As a result,the tensile property differences in sample top and bottom for AB and DA conditions did not occur in the STA samples.For the influence of post-process heat treatment,the STA condition had the highest yield strength due to the highest volume fraction of nano-sized Cu precipitates.However,the DA specimen had the highest ultimate tensile strength and elongation owing to the considerable amount of austenite phase and associated transformation induced plasticity effect.展开更多
Microstructure transformation and aging hardening behavior of 15-5 PH stainless steel were studied by optical microscopy （OM）, X-ray diffraction （XRD） and transmission electron microscopy （TEM）. The results show...Microstructure transformation and aging hardening behavior of 15-5 PH stainless steel were studied by optical microscopy （OM）, X-ray diffraction （XRD） and transmission electron microscopy （TEM）. The results showed that the 15-5 PH stainless steel consists of NbC precipitates and lath matensite with a high dislocation density after solution treatment. With increasing aging temperature and aging time, the martensitic laths were resolved gradually. Meanwhile, the nanometric-sized Cu precipitates gradually coarsened and lost their coherency with＇the martensite matrix, which exhibited an elliptical shape finally. Fine Cu precipitates can lead to significant dispersion hardening effect, while the coarsened Cu precipitates have no contribution to strengthening. The reversed austenite was observed in the speci- mens aged at 550 ℃ and above; moreover, the amount of reversed austenite increased as aging temperature in- creased. The precipitation hardening behavior of 15-5 PH stainless steel may depend on the balance between the softening caused by the formation of reversed austenite and the hardening caused by the precipitation of copper.展开更多
The stress corrosion cracking（ SCC） behavior of PH13-8Mo precipitation hardening stainless steel（ PHSS） in neutral NaCl solutions was investigated through slow-strain-rate tensile（ SSRT） test at various applied ...The stress corrosion cracking（ SCC） behavior of PH13-8Mo precipitation hardening stainless steel（ PHSS） in neutral NaCl solutions was investigated through slow-strain-rate tensile（ SSRT） test at various applied potentials. Fracture morphology,elongation ratio,and percentage reduction of area were measured to evaluate the SCC susceptibility. A critical concentration of 1. 0 mol / L neutral NaCl existed for SCC of PH13-8Mo steel. Significant SCC emerged when the applied potential was more negative than -0. 15 VSCE,and the SCC behavior was controlled by an anodic dissolution（ AD） process.When the applied potential was lower than -0. 55 VSCE,an obvious hydrogen-fracture morphology was observed,which indicated that the SCC behavior was controlled by hydrogen-induced cracking（ HIC）.Between -0. 15 and -0. 35 VSCE,the applied potential exceeded the equilibrium hydrogen evolution potential in neutral NaCl solutions and the crack tips were of electrochemical origin in the anodic region; thus,the SCC process was dominated by the AD mechanism.展开更多
以实际工艺流程50 t EBT-VOD-LF-VC冶炼15-5PH不锈钢为背景,通过FactSage 8.0和经典Wagner模型研究冶炼硅铝复合脱氧过程中钢液中的铝含量、炉渣组成以及冶炼温度等因素对钢液中氧含量的影响进行了热力学研究。结果表明:Al-Si复合脱氧为...以实际工艺流程50 t EBT-VOD-LF-VC冶炼15-5PH不锈钢为背景,通过FactSage 8.0和经典Wagner模型研究冶炼硅铝复合脱氧过程中钢液中的铝含量、炉渣组成以及冶炼温度等因素对钢液中氧含量的影响进行了热力学研究。结果表明:Al-Si复合脱氧为15-5PH不锈钢冶炼过程中的最佳脱氧工艺,为了保证脱氧的冶炼效果,应控制钢液中的酸溶铝的质量分数在0.015%左右;降低冶炼温度有利于降低钢液平衡氧含量;考虑炉渣的物理性能和钢渣界面平衡反应得出脱氧工艺的最优炉渣成分,碱度为2.5~3.0,w((Cr_(2)O_(3)))=0.5%,w((Al_(2)O_(3)))=20%,w((MgO))=5%,w((CaF_(2)))=5%;经过工艺优化后生产的15-5PH不锈钢中氧含量明显降低,均满足产品要求,炉渣碱度对平衡氧含量和实际生产全氧含量的影响规律基本相同。展开更多
基金Sheng Cao thanks the support from the National Natural Science Foundation of China(No.52204391)the Special Fund Project for Science and Technology Innovation Strategy of Guangdong Province(Nos.STKJ202209021 and STKJ2023040)+1 种基金the Characteristic Innovation Project(Natural Science)for Regular University in Guangdong Province(No.2022KTSCX038)the Shantou University Research Foundation for Talents(No.NTF21013).
文摘This work investigated the gradient microstructure evolution and tensile property of LPBF fabricated 15-5 precipitation hardening stainless steel in post-process direct ageing(DA)and solution treating&ageing(STA).The varied microstructures for austenite and small-sized oxide inclusions at different sample heights in the as-built(AB)condition was generally preserved after DA treatment.However,austenite was almost disappeared,and oxide particle grew significantly after the STA treatment.As a result,the tensile property differences in sample top and bottom for AB and DA conditions did not occur in the STA samples.For the influence of post-process heat treatment,the STA condition had the highest yield strength due to the highest volume fraction of nano-sized Cu precipitates.However,the DA specimen had the highest ultimate tensile strength and elongation owing to the considerable amount of austenite phase and associated transformation induced plasticity effect.
基金Item Sponsored by National High Technology Research and Development Program of China(2012AA03A507)Key Laboratory Foundation of Metal Material Microstructure Control of Jiangxi Province of China(JW201223001)Foundation of Jiangxi Educational Committee of China(GJJ14534)
文摘Microstructure transformation and aging hardening behavior of 15-5 PH stainless steel were studied by optical microscopy （OM）, X-ray diffraction （XRD） and transmission electron microscopy （TEM）. The results showed that the 15-5 PH stainless steel consists of NbC precipitates and lath matensite with a high dislocation density after solution treatment. With increasing aging temperature and aging time, the martensitic laths were resolved gradually. Meanwhile, the nanometric-sized Cu precipitates gradually coarsened and lost their coherency with＇the martensite matrix, which exhibited an elliptical shape finally. Fine Cu precipitates can lead to significant dispersion hardening effect, while the coarsened Cu precipitates have no contribution to strengthening. The reversed austenite was observed in the speci- mens aged at 550 ℃ and above; moreover, the amount of reversed austenite increased as aging temperature in- creased. The precipitation hardening behavior of 15-5 PH stainless steel may depend on the balance between the softening caused by the formation of reversed austenite and the hardening caused by the precipitation of copper.
基金supported by the National Natural Science Foundation of China(No.51171023)the Fundamental Research Funds for the Central Universities(No.FRF-TP-14-011C1)+1 种基金National Basic Research Program of China(973 Program )(No.2014CB643300 )the Beijing Municipal Commission of Education
文摘The stress corrosion cracking（ SCC） behavior of PH13-8Mo precipitation hardening stainless steel（ PHSS） in neutral NaCl solutions was investigated through slow-strain-rate tensile（ SSRT） test at various applied potentials. Fracture morphology,elongation ratio,and percentage reduction of area were measured to evaluate the SCC susceptibility. A critical concentration of 1. 0 mol / L neutral NaCl existed for SCC of PH13-8Mo steel. Significant SCC emerged when the applied potential was more negative than -0. 15 VSCE,and the SCC behavior was controlled by an anodic dissolution（ AD） process.When the applied potential was lower than -0. 55 VSCE,an obvious hydrogen-fracture morphology was observed,which indicated that the SCC behavior was controlled by hydrogen-induced cracking（ HIC）.Between -0. 15 and -0. 35 VSCE,the applied potential exceeded the equilibrium hydrogen evolution potential in neutral NaCl solutions and the crack tips were of electrochemical origin in the anodic region; thus,the SCC process was dominated by the AD mechanism.
文摘以实际工艺流程50 t EBT-VOD-LF-VC冶炼15-5PH不锈钢为背景,通过FactSage 8.0和经典Wagner模型研究冶炼硅铝复合脱氧过程中钢液中的铝含量、炉渣组成以及冶炼温度等因素对钢液中氧含量的影响进行了热力学研究。结果表明:Al-Si复合脱氧为15-5PH不锈钢冶炼过程中的最佳脱氧工艺,为了保证脱氧的冶炼效果,应控制钢液中的酸溶铝的质量分数在0.015%左右;降低冶炼温度有利于降低钢液平衡氧含量;考虑炉渣的物理性能和钢渣界面平衡反应得出脱氧工艺的最优炉渣成分,碱度为2.5~3.0,w((Cr_(2)O_(3)))=0.5%,w((Al_(2)O_(3)))=20%,w((MgO))=5%,w((CaF_(2)))=5%;经过工艺优化后生产的15-5PH不锈钢中氧含量明显降低,均满足产品要求,炉渣碱度对平衡氧含量和实际生产全氧含量的影响规律基本相同。
