445M铁素体不锈钢缝隙腐蚀性能的研究

研究了445M铁素体不锈钢(%:0.004～0.005C、22.24～22.29Cr、1.10～1.65Mo、0.015～0.016P、0.003～0.004S、0.012～0.016N、0.22～0.38Ti)和316L奥氏体不锈钢(%:0.022C、16.80Cr、10.19Ni、2.02Mo、0.025P、0.001S、0.046N)在40～60℃氯离子浓度(250～5 000)×10^-6的氯化钠溶液的缝隙腐蚀性能。结果表明,445M铁素体不锈钢的耐缝隙腐蚀性能优于316L奥氏体不锈钢;当445M钢中的Mo含量由1.10%提高至1.65%时,钢的耐缝隙腐蚀性能明显提高,表明点蚀当量Cr+3.3Mo是衡量不锈钢耐点蚀和耐缝隙腐蚀的重要指标。     

可望替代SUS相类似牌号的机械结构用高氮不锈钢的开发

虽然SUS304和SUS316的耐蚀性较好,但作为结构材料尚有不足,在含有氯离子的腐蚀环境下容易发生点蚀等耐蚀性问题尚待解决。因此,作为其替代材料,近来高氮不锈钢引起了人们的关注。本文介绍耐海水性、高强度、非磁性高氮奥氏体不锈钢的开发     

Low molybdenum ultra-pure ferritic stainless steel for solar water heaters

In order to meet the demands of service life and the synthetical performance/price ratio of stainless steel in the solar water heater industry,the low molybdenum ultra-pure ferritic stainless steel(FSS) B445J1M was developed at Baosteel.In this study,comparative studies were carried out on the mechanical properties,the formability and the corrosion resistance of B445J1M,304 and 444,and the advantages and application fields of B445J1M were summarized.     

443高铬铁素体不锈钢耐蚀性能评价

通过盐雾试验、电化学试验和应力腐蚀试验,并结合扫描电镜,对比研究了443超纯铁素体不锈钢和304奥氏体不锈钢的耐腐蚀性能。结果表明:碳、氮间隙元素极低的高铬443超纯铁素体不锈钢点腐蚀速率小于304奥氏体不锈钢,具有比304更优异的耐氯离子腐蚀性能;同时,443不锈钢不具有晶间腐蚀敏感性,而304具有严重的晶间腐蚀敏感性;304不锈钢有可能发生应力腐蚀断裂,443不锈钢没有这种危险。可见,443超纯铁素体不锈钢是304奥氏体不锈钢理想的替代材料,可用于电梯、建筑装饰、厨具等众多行业。     

NKK研究出耐海水腐蚀的复层不锈钢

NKK已研制出耐海水腐蚀性能好的第一块不锈钢复层板。过去普遍使用的SUS304、SUS316钢耐海水腐蚀性差,而其他产品如高Ni-Cr ASTMA240 S31254钢,虽然耐海水腐蚀,但是价格高。最初,在制造耐海水不锈钢复层板时,由于在包覆过程中不锈钢易于活化,而造成耐腐蚀性明显降低。通过添加特殊元素以及使Cr(25%)、Ni(22%)、Mo(4.5%)的不锈钢可加工性大大提高,因而耐腐蚀性能明显改善。     

B443超低碳氮铁素体不锈钢的研究

为开发价格昂贵的SUS304奥氏体不锈钢的替代产品,试验研究了不同含量C N和Nb,Ti稳定化对B443系列铁素体不锈钢再结晶组织、力学性能、点蚀电位的影响.试验结果表明,Nb,Ti双稳定化提高了B443铁素体不锈钢的再结晶温度和点蚀电位.在试验室研究基础上,宝钢不锈钢分公司试制了B443NT超低碳氮铁素体不锈钢.该产品不仅具有与SUS304相当的耐腐蚀性能,而且具有优良的深拉伸性能和满意的焊接性能,可用于运输、建筑、厨具等众多行业.     

445J2超纯铁素体不锈钢和316L超低碳奥氏体不锈钢在溴化锂溶液的点蚀分析

445J2铁素体不锈钢由于高的导热率、低的热膨胀系数以及良好的耐蚀性能使得其作为溴冷机中一些部件的良好候选材料,本文采用电化学测试方法对比研究了445J2超纯铁素体不锈钢(/%:0.01C,22.5Cr, 1.9Mo, 0.27Nb, 0.20Ti, 0.09Al, 0.36Cu, 0.015P,0.001S,0.015N)和316L奥氏体不锈钢(/%:0.002C,16.8Cr, 10.19Ni, 2.02Mo, 0.025P,0.0008S)在20～60℃0.1～1M的溴化锂溶液中的点蚀行为,并采用扫描电镜(SEM)和能谱分析仪(EDS)对电化学结果进行表征。结果表明,随着LiBr温度和浓度的升高,两种钢腐蚀电流密度增大,点蚀电位降低,耐点蚀性变差;氧化物和硫化物夹杂会引起两种钢的点蚀;高含量的Cr以及Mo、Ti、Nb、Al等合金元素使445J2钢具有优异的耐点蚀性能。     

钴元素对SUS304不锈钢耐点腐蚀性能的影响

开发红土镍矿是解决镍资源危机的重点,由于红土镍矿中钴和镍伴生,导致不锈钢中钴元素的存在。本文以SUS304不锈钢钢板和电解钴为原料,采用真空感应冶炼炉和三高石墨铸模浇铸不同钴含量试样,利用线切割机加工腐蚀试样,进行三氯化铁点腐蚀试验。试验结果表明：钴元素的加入增大了铸态SUS304不锈钢点腐蚀敏感性,降低了铸态SUS304不锈钢耐点腐蚀性能,当钴含量小于0．3％时,点腐蚀速率没有增加,当钴含量为0．4％和0．5％时,点腐蚀速率明显增大。     

宝新深冲产品应用分析

为开发深冲用冷轧不锈钢产品（即DDQ产品）,扩大宝钢不锈钢在冷冲压制品市场的占有率,在对奥氏体不锈钢形变理论分析及冷冲压制品市场调研的基础上,对304系列钢种中的304Ni8.5、304Ni9及SUS304Cu按不同工艺进行了试制生产,并将试制产品供不同成形方式制品加工试用。试用结果表明：宝新304Ni8.5、304Ni9及SUS304Cu深冲系列产品具有较好的流动性,较适合于热水器内胆等以拉深成形为主要成形方式的冲压加工,其中304Ni8.5及SUS304Cu的极限深冲比在2.4以上、304Ni9的极限深冲比可达2.9以上,而水槽等以胀形为主要成形方式的冲压制品,使用宝新一般冲压类产品更为适合。     

合金元素对铁素体不锈钢耐应力腐蚀开裂性能的影响

通过42%沸腾氯化镁U型弯曲试验,结合扫描电子显微镜、X射线衍射分析,研究了合金元素Ni、Cu、Mo对铁素体不锈钢耐氯化物应力腐蚀开裂性能的影响规律。结果表明,Ni、Cu元素能够提高铁素体不锈钢应力腐蚀开裂的敏感性,单独添加Mo元素不会降低铁素体不锈钢耐应力腐蚀开裂的能力,但是钢中Mo、Cu元素同时存在时,应力腐蚀开裂的敏感性大大增加。钢中析出的ε-Cu在氯离子环境中形成点蚀,引起了铁素体不锈钢应力腐蚀开裂。     

Investigation on the cold-strip breakage of SUS445J2 ultra-pure ferritic stainless steel during rolling process

In this work,the cause of the cold-strip breakage of SUS445J2 ultra-pure ferritic stainless steel was investigated using optical microscopy,energy dispersive spectroscopy,and electron backscatter diffraction technique.Results show that during cold rolling,the breakage of the stainless steel strip was mainly caused by massive niobium-rich(Nb-rich)carbides present in the center of the strip.Furthermore,cracks initiated at these carbides in the central layer.The massive carbide precipitates resulted from the segregation and enrichment of Nb,titanium(Ti),and carbon(C)in the central layer during the subsequent solidification stage of SUS445J2 stainless steel.Additionally,the banded structure and coarse ferrite grains in the central layer reduced the plasticity of the material,causing cracks to propagate along these grains and finally leading to cold-strip breakage.By reducing the solidification cooling rate of the billet,increasing the pouring temperature,discretizing Nb,Ti,and C enrichment via electromagnetic stirring,and forming equiaxed crystals in the central layer,the precipitation of harmful massive Nb-rich carbides in the central layer could be effectively avoided.     

Development of ferritic stainless steel B445R with superior corrosion resistance for architectural applications

The dull-finish ferritic stainless steel(FSS) sheet B445R for architectural roofing has been developed by Baosteel.This steel product exhibits excellent corrosion resistance superior to that of SUS 316L with a lower cost.It can be easily formed into roofing panels by ordinary processes.Moreover,the thermal strain of it is less than SUS 316L because of its lower thermal expansion coefficient,and its reflectivity is lower due to the dull-finish treatment.All of these features make it capable of being used as architectural roofing materials in coastal regions.     

建筑用高耐蚀性铁素体不锈钢B445R的研制

宝钢研制出了建筑屋顶装饰用铁素体不锈钢B445R毛面产品。该产品的耐蚀性比奥氏体不锈钢SUS316L更优越,成本也比SUS316L低,采用常规的成形方法就可以将其加工成屋顶面板。此外,由于该产品的热膨胀系数比SUS316L小,故其热变形也比SUS316L小,同时由于进行了毛化处理,其表面具有较低的光反射能力。所有这些优点使其有能力成为沿海地区建筑物的屋顶装饰材料。     

SUS444不锈钢断带成因和解决途径

SUS444冷轧不锈钢带钢在生产过程中发生频繁的断带事故,导致产品不能及时交货。分析了SUS444不锈钢板坯移库、穿带震动以及修磨过程的环境温度等工序的作业特点,特别当材料的加工截面尺寸较大时,因塑韧性偏低、对环境温度敏感等特性,容易发生断裂失效。研究了材料自身夹杂物的内在诱因与断带的关联度。提出了一些工艺改进措施,有效地控制了SUS444的断带事故,为保证用户合同及时完成和恢复生产提供了技术支撑。     

High performance ferritic stainless steel B445R for architectural applications

Traditionally,austenitic stainless steels 304 and 316 have been employed in coastal regions as roofing materials unfortunately,they are expensive and not fully resistant to pitting corrosion under severe coastal corrosive environment.A ferritic stainless steel B445R was developed.Compared with austenitic 316L,B445R is①less costly;②uperior corrosion resistant with minor maintenance for long-term service;③insusceptible to thermal distortion in the welding seam. B445R sheet shows a higher yield strength and lower tensile strength,lower elongation and lower work-hardening than austenitic 316L.It can be easily fabricated and deformed just like plain carbon steel.After bending 180o,there is no occurrence of "cracking" or noticeable "orange peel".The formability of the welding seam is also satisfactory.The pitting potential of B445R is 650 mV,larger than that of 304 and 316L,as shown in Fig.1. The corrosion rate of B445R submerged in 6%FeCl,solution is 0.3 -0.56 g/(m² ? h^-1),much lower than that of 316L,as shown in Fig.2.The superior pitting corrosion resistance of B445R can be ascribed to synergetic effect of higher Cr and Mo. Dull-finished B445R sheets have been employed as the roofing materials for Guangzhou Asian Games Arena,as shown in Fig.3.About 380 t of 1.0 mm B445R with dull finish was used for roofing panels.About 100 t of 0.8 mm B445R with hairline or fluororesin paint finish was used for side wall panels.The composite roof build-up （from up to bottom） includes:①shingles of ferritic stainless steel B445R;②Kalzip-type standing seam of austenitic 304;③water-proof DFM;④structural steel;⑤75 mm thick insulation;⑥secondary purlin of 150 mm×100 mm×4.5 mm of galvanizied Q235;⑦0.8 mm thick profile deck of galvanizied Q235;⑧acoustic insulation.The roofing shingles or panels with the same width but different length were formed by bending four sides and fixed to a "L" shape reinforcing frames of stainless steel by fasteners.The "L" frames was connected to ribs of the standing seam by a clamping fixture made of aluminum.     

SUS430不锈钢夹杂物的变化规律研究

对采用EAF-AOD-LF-CC工艺路线生产SUS430不锈钢炼钢过程夹杂物的成分组成和形貌、尺寸变化进行了分析,结果表明,SUS430不锈钢中主要形成呈球状或不规则球状分布的硅酸盐复合夹杂物,其变形能力较差。随着LF精炼和连铸过程的进行,SUS430不锈钢钢水中夹杂物的平均直径呈逐渐减小的趋势,铸坯夹杂物的平均直径为3.4μm左右,5μm以上的夹杂物占夹杂物总数的1%以下。变形能力较差的硅酸盐夹杂和镁铝尖晶石夹杂是引起SUS430不锈钢冷轧板表面线鳞缺陷的重要原因,采用钙处理和复合脱氧工艺,对改善SUS430不锈钢冷轧板的表面线鳞缺陷有利。