Influence of vanadium and/or niobium additions on delayed fracture behavior in high strength spring steel was studied by hydrogen permeation method and slow strain rate technique （8SRT）, and its mechanism was analyz...Influence of vanadium and/or niobium additions on delayed fracture behavior in high strength spring steel was studied by hydrogen permeation method and slow strain rate technique （8SRT）, and its mechanism was analyzed. The results show that apparent diffusion coefficient of hydrogen in microalloyed spring steels Nb-V-steel and Nb-steel is lower than that in non-microalloyed steel 60Si2MnA. Percentage of strength reduction in SSRT in air after precharged hydrogen of the microalloyed steels is smaller than that of 60Si2MnA. Addition of the microalloys changes the fracture characteristics. Thence, vanadium and/or niobium additions are a very effective and economy means to improve the hydrogen-induced delayed fracture resistance of high strength spring steel.展开更多
This work aims at the development of carbon steel AISI 1536 through the microalloying addition of boron. Three grades of this steel with different content of boron up to 0.0055% were melted in 100 kg induction furnace...This work aims at the development of carbon steel AISI 1536 through the microalloying addition of boron. Three grades of this steel with different content of boron up to 0.0055% were melted in 100 kg induction furnace. The pro- duced steels were hardened at 960°C for 30 min., followed by tempering at different temperatures and durations. All hardened steels have martensite phase as illustrated with microstructures and X-ray diffraction. Hardness of all tem- pered steel samples was measured to calculate the activation energies of carbon migration through martensite phase. The results indicated that the activation energies of carbon migration through martensite phase decreases with the in- crease of boron content due to its positive effect on the crystallinity of martensite phase. Also, the results showed that the addition of boron up to 0.0023% can improve the steel properties at the lowest temperature and tempered time.展开更多
Understanding the weldability of steel in relation to the use of carbon equivalent is very necessary </span><span style="white-space:normal;font-family:"">for</span><span style...Understanding the weldability of steel in relation to the use of carbon equivalent is very necessary </span><span style="white-space:normal;font-family:"">for</span><span style="white-space:normal;font-family:""> the welding industry. The study was poised to unearth the fundamentals of carbon equivalent as applied in evaluating the weldability of steel. The study used </span><span style="white-space:normal;font-family:"">a </span><span style="white-space:normal;font-family:"">two-stage design approach to address the problem of carbon equivalence weldability of steel, thus, survey and experimental. Two different steels were tested to ascertain their chemical composition which could inform carbon equivalent calculation, and the results revealed microalloy and low alloy steels respectively. In subjecting the microalloy steel to carbon equivalent analyses of the AWS and IIW coefficients;revealed a value (CEV) = 0.11 each, suggesting that this microalloy steel has excellent weldability;no preheat</span><span style="white-space:normal;font-family:"">ing</span><span style="white-space:normal;font-family:""> is required. A successful welding operation on this steel does not depend on preheat</span><span style="white-space:normal;font-family:"">ing</span><span style="white-space:normal;font-family:"">.<b> </b>Also</span><span style="white-space:normal;font-family:"">,</span><span style="white-space:normal;font-family:""> the average results of the low alloy steel revealed a value (CEV) = 0.37 and 0.32 respectively, suggesting that this type of steel has very good weldability and may require </span><span style="white-space:normal;font-family:"">to </span><span style="white-space:normal;font-family:"">preheat. It is recommended that welders have </span><span style="white-space:normal;font-family:"">a </span><span style="white-space:normal;font-family:"">general idea about the weldability of steel with regard to carbon equivalent calculation. In addition</span><span style="white-space:normal;font-family:"">,</span展开更多
基金Item Sponsored by CITIC-CBMM Niobium Steel Research and Development Projects of China(2007RMJS-D031)
文摘Influence of vanadium and/or niobium additions on delayed fracture behavior in high strength spring steel was studied by hydrogen permeation method and slow strain rate technique （8SRT）, and its mechanism was analyzed. The results show that apparent diffusion coefficient of hydrogen in microalloyed spring steels Nb-V-steel and Nb-steel is lower than that in non-microalloyed steel 60Si2MnA. Percentage of strength reduction in SSRT in air after precharged hydrogen of the microalloyed steels is smaller than that of 60Si2MnA. Addition of the microalloys changes the fracture characteristics. Thence, vanadium and/or niobium additions are a very effective and economy means to improve the hydrogen-induced delayed fracture resistance of high strength spring steel.
文摘This work aims at the development of carbon steel AISI 1536 through the microalloying addition of boron. Three grades of this steel with different content of boron up to 0.0055% were melted in 100 kg induction furnace. The pro- duced steels were hardened at 960°C for 30 min., followed by tempering at different temperatures and durations. All hardened steels have martensite phase as illustrated with microstructures and X-ray diffraction. Hardness of all tem- pered steel samples was measured to calculate the activation energies of carbon migration through martensite phase. The results indicated that the activation energies of carbon migration through martensite phase decreases with the in- crease of boron content due to its positive effect on the crystallinity of martensite phase. Also, the results showed that the addition of boron up to 0.0023% can improve the steel properties at the lowest temperature and tempered time.
文摘Understanding the weldability of steel in relation to the use of carbon equivalent is very necessary </span><span style="white-space:normal;font-family:"">for</span><span style="white-space:normal;font-family:""> the welding industry. The study was poised to unearth the fundamentals of carbon equivalent as applied in evaluating the weldability of steel. The study used </span><span style="white-space:normal;font-family:"">a </span><span style="white-space:normal;font-family:"">two-stage design approach to address the problem of carbon equivalence weldability of steel, thus, survey and experimental. Two different steels were tested to ascertain their chemical composition which could inform carbon equivalent calculation, and the results revealed microalloy and low alloy steels respectively. In subjecting the microalloy steel to carbon equivalent analyses of the AWS and IIW coefficients;revealed a value (CEV) = 0.11 each, suggesting that this microalloy steel has excellent weldability;no preheat</span><span style="white-space:normal;font-family:"">ing</span><span style="white-space:normal;font-family:""> is required. A successful welding operation on this steel does not depend on preheat</span><span style="white-space:normal;font-family:"">ing</span><span style="white-space:normal;font-family:"">.<b> </b>Also</span><span style="white-space:normal;font-family:"">,</span><span style="white-space:normal;font-family:""> the average results of the low alloy steel revealed a value (CEV) = 0.37 and 0.32 respectively, suggesting that this type of steel has very good weldability and may require </span><span style="white-space:normal;font-family:"">to </span><span style="white-space:normal;font-family:"">preheat. It is recommended that welders have </span><span style="white-space:normal;font-family:"">a </span><span style="white-space:normal;font-family:"">general idea about the weldability of steel with regard to carbon equivalent calculation. In addition</span><span style="white-space:normal;font-family:"">,</span
