矿山支护用热轧36U型钢开裂分析

通过分析化学成分、显微组织和夹杂物对矿山支护用热轧36U型钢开裂的原因进行了分析。结果表明:非金属夹杂物是导致36U型钢开裂的主要原因,基体中带状组织严重,并存在异常贝氏体组织均能引起钢材开裂。并提出了预防措施。     

AH36高强度船板拉伸试样断口分离原因分析

宝钢在生产A36船板钢的过程中,个别拉伸试样产生了断口分离现象。本文结合A36船板钢的冶炼和轧制实际情况,对分离严重部位进行了理化检验,分析结果表明：中心偏析和明显的带状组织是造成拉伸断口分离的根本原因。本文对此提出了相应的改进措施,以减少此类缺陷的产生。     

FH36高强度船板组织和性能研究

采用NbTi微合全化成分设计以及TMCP工艺轧制,在实验室成功研制了TMCP-FH36船体结构用钢。试验钢轧态组织为“铁素体＋贝氏体＋珠光体”,晶粒细小,综合力学性能完全满足船级社规范要求,特别是在-60℃试验温度下,冲击功达到200J以上。     

DH36钢在模拟海洋环境干湿交替过程中的腐蚀行为

海洋环境中钢铁设备会受到严重腐蚀,浪花飞溅区的干湿交替状况下最为严重,对钢铁在该环境下腐蚀机理的研究很有必要。以模拟全浸区钢样作对比,利用扫描电镜和x射线衍射仪对DH36j海洋用钢试样的腐蚀形貌和腐蚀产物成分进行了分析,探讨了其在干湿交替过程中的腐蚀规律及其机理。结果表明：干湿交替DH36钢试样阴极过程的溶解氧还原的极限扩散控制特征基本消失,而受腐蚀产物还原为主的电荷传递控制;干湿交替钢样生成的腐蚀产物较多,锈层自身氧化剂的作用使得阴极电流变大,导致模拟干湿交替试样的腐蚀速率远大于全浸区试样的。     

在扩径过程中DH36钢管开裂原因分析

海洋平台用DH36钢管在扩径过程中出现开裂,采用化学成分分析、扫描电镜分析、能谱分析、氧化分析、金相检验等方法对钢管的开裂原因进行了分析。结果表明:该DH36钢管开裂是由钢板原始缺陷引起的。钢坯在加热炉中加热时,缺陷表面再次发生氧化形成氧化圆点,轧制时缺陷被碾压变形,形成裂纹;在钢管扩径时,裂纹扩展最终导致钢管开裂。     

A32/A36船板钢拉伸试验分层缺陷原因分析及冶炼工艺改进

A32/A36船板钢在拉伸试验后出现了分层缺陷。利用光学显微镜、扫描电镜和能谱仪对分层缺陷严重的部位进行了分析。结果表明:分层缺陷主要与铸坯中存在元素偏析形成的铌、钛碳化物和硫化物夹杂有关。提出了改进冶炼和轧制工艺等相关措施并应用于实际生产,使废品率由12%降低到5%。     

热输入对E36钢SAW焊缝组织及韧性的影响

为提高建造海洋采油平台的效率、减少生产周期,进而为实际生产提供数据支持,采用3种不同热输入对海洋采油平台用E36钢进行埋弧焊焊接,通过光学显微镜(OM)、透射电镜(TEM)、扫描电镜(SEM)和电子背散射衍射技术(EBSD)对焊缝微观组织及夹杂物形貌进行了观察,研究了不同热输入对焊缝组织及韧性的影响,并分析了不同热输入对焊缝夹杂物尺寸分布和成分的影响.结果表明:热输入为50 k J/cm时,焊缝金属韧性较好;随着焊接热输入的增加,焊缝的冲击韧性降低,但仍能满足性能指标,焊缝金属中夹杂物成分相差较大,有效夹杂物数量减少,焊缝金属中大角度晶界比例减少;对于E36钢,热输入为160 k J/cm时不仅能使韧性符合要求还能提高生产效率.     

提高高强度钢使用寿命的科技进展

系统介绍了近5年在国家973重大基础研究规划支持下,由一支多专业结合的团队,开展了"提高钢铁质量和使用寿命的冶金学基础研究".为提高工程结构用钢的使用寿命,研究了高强度廉价耐候钢,特别是Mn-Cu-细晶,P-RE-超细晶的协同作用和超低碳贝氏体组织对钢耐蚀性的影响;为提高机械制造用钢的使用寿命,研究了高强度钢的超高周疲劳断裂机制,特别是夹杂物尺寸对钢疲劳性能的影响;为提高合金结构钢的质量研究了微米级夹杂物的形成理论和控制技术.     

利用TMCP开发F550高强度船板钢的实验研究

使用Gleeble 3800热模拟实验机研究了一种低C微合金SiMnCrNiMo钢的奥氏体连续冷却相变(CCT)行为,使用辊径750mm的二辊可逆实验轧机进行了系列TMCP实验,开发出F550高强度船板。生产F550船板的TMCP工艺为:在奥氏体再结晶区和未再结晶区进行两阶段轧制,精轧温度800～820℃,精轧压下率67%,轧后以14～18℃/s的速率冷却至350～500℃。钢板的显微组织为细密贝氏体,其屈服强度大于590MPa,抗拉强度大于700MPa,-60℃下Charpy冲击吸收能量高于230J。     

40Cr钢油缸断裂原因

采用宏观观察、化学成分分析、金相检验、扫描电镜和能谱分析、显微硬度测试等方法分析了40Cr钢油缸断裂的原因。结果表明：油缸断裂主要与硫元素含量超标、硫化物聚集、表面凹坑缺陷及热处理不均匀有关;硫元素易产生“热脆”,聚集的条状夹杂物破坏了基体的连续性,使油缸产生微裂纹,在表面凹坑处产生应力集中,热处理不均匀使组织产生内应力,萌生的裂纹及表面凹坑在以上因素的作用下不断扩展,最终导致油缸断裂。     

Temperature‐dependent characteristics of DH36 steel fatigue crack propagation

DH36 steel is a widely used material in marine engineering. The fatigue crack propagation rates of DH36 steel at low temperatures have a crucial influence on the fatigue strength of structures operating in polar environments. The objective of this paper is to investigate the fatigue crack propagation behaviour of DH36 steel at low temperatures (?60°C to 20°C) by carrying out tensile tests and fatigue crack propagation tests of DH36 steel, in order to obtain the fatigue crack propagation behaviour of DH36 steel. The influence of the elastic modulus on the crack length measured by the compliance method is considered. On the basis of the Paris law, the crack propagation rate at different temperatures is investigated. The results and the observed failure modes indicated that fatigue ductile‐to‐brittle transition (FDBT) occurred as the temperature was lowered.     

E36船体结构钢板水火弯板工艺适应性研究

采用不同加热温度对E36船体结构钢板进行热弯曲试验。结果表明,E36船体结构钢板具有良好的水火弯板工艺适应性,水火弯板后钢板性能均能满足要求,其强度略有升高,塑性略有下降,加热温度750℃时冲击韧性变化不大,加热温度800℃时冲击韧性显著降低,这可能是由于较高加热温度导致了焰道中心晶粒粗大所致。     

Nb-B复合高强度集装箱板的组织与性能

为研究Nb-B复合高强度集装箱板的相变规律,研究终轧温度和轧后冷却速度对钢板组织和力学性能的影响规律以及钢板的耐腐蚀性能,利用Gleeble-1500热模拟试验机测定了实验钢的动态CCT曲线,在实验室轧机上进行热轧实验,并采用盐雾腐蚀试验（NSS）和周期侵蚀试验（NaHSO3）检验实验钢的腐蚀性能.结果表明：实验钢动态...     

应用炉卷轧机开发700MPa级高强韧性钢板

700MPa级高强韧性钢板具有强度高、低温韧性好以及焊接性能优良的特点.然而,传统的铁素体/珠光体钢的屈服强度一般低于500MPa,不能满足强度要求.本研究采用现代炉卷轧机并结合控轧控冷工艺在安阳钢铁公司研制开发出700MPa级高强韧性钢板,其屈服强度大于560MPa、抗拉强度大于670MPa、延伸率大于16%、-40℃冲击功大于47J.     

Investigation on processing of ASTM A131 Eh36 high tensile strength steel using selective laser melting

ABSTRACT

In this paper, selective laser melting (SLM) technique was used to investigate the processing of EH36 high tensile strength steel commonly used in the shipbuilding applications. EH36 powder was produced according to ASTM A131 standards using gas atomisation process. SLM process parameters, including scanning speed and hatch spacing, were investigated to produce test specimens with high density. Parts were successfully built using SLM without cracks. Density tests were performed according to ASTM B962 standards. Light optical microscopy and scanning electron microscopy showed slight porosities and martensitic microstructure respectively. The study concluded that EH36 parts could be produced using SLM and this provided foundation work for the technical feasibility of fabricating high tensile strength steel components for the shipbuilding industry.     

590MPa高强度船用钢板调质工艺的优化

为提高590 MPa船用钢板的综合力学性能,对40 mm厚船用HQ60T钢板进行了调质工艺的研究.采用不同的正火工艺获得了不同的组织结构,进行了不同淬火和回火温度的热处理试验,对不同试样进行了金相分析和力学性能的试验,详细观察了各种热处理状态下试验钢的微观组织,讨论了组织演变规律及其对性能的影响.试验表明:相同调质处理条件下,随着正火温度的提高,钢板强度下降,韧性提高;在580℃回火的条件下,韧性指标随淬火温度的升高,先升高后降低,在920℃时出现峰值;回火温度高于580℃,钢板韧性下降,强度下降加快.研究表明,在920℃时水淬,然后580℃回火时钢板综合力学性能最好.     

The effects of strength models in numerical study of metal plate destruction by contact explosive charge

Based on a complete mathematical model, the authors set up a problem of metal plate destruction by contacting explosive charge in highly nonlinear dynamic software AUTODYN and solved in two cases using the Johnson–Cook and von Mises strength models. The numerical simulation results were compared with the experimental results and showed a good fit of numerical calculations versus experiments by using the von Mises strength model. The study also shows that the Johnson–Cook strength model, if applied unreasonably, will lead to large errors, which would help to avoid mistakes in the future high speed impact study.     

Effect of high filling ratio on the weld strength of hot plate welded calcite filled polypropylene and its comparison with talc filling

In this paper, the effect of the hot plate welding parameters on the weld strength of 40 % calcite filled polypropylene were investigated by utilizing design of experiment and compared to talc filled polypropylene. The plate temperature and the heating time were considered as the process parameters. A mathematical predictive model of the weld strength was developed in terms of welding parameters. The results show that the mathematical model correlates well with the experimental results. The optimum welding parameters of calcite filled polypropylene are determined as 260 °C of plate temperature and heating time of 25 s. The welding strength of the joint welded at optimum parameters is found as 18.32 MPa. Hot plate welding efficiency of the 40 % calcite filled polypropylene is observed to be higher than 40 % talc filled polypropylene material.