Microstructure and Properties of Superplastic Welding between 4OCr and CrWMn Steels

Superplastic welding of tool steel and structural steel was investigated. The welding between 40Cr and CrWMn steels was carried out under the conditions of temperature 750～780°C, strain rate 2×10-4 s-1, compressive stress 50～90 MPa for 3～5 min. The joints show similar strength to that of 40Cr steel and the good metallurgical joining is formed. The structural change occurring during superplastic welding was analyzed by metallography and distribution of carbon content in the vicinity of the welding joint was also determined. The mechanism of superplastic welding for steels is proposed to be the disappearance of original bond interfaces caused by atomic diffusion and the grain sliding.     

钢的恒温超塑性固相焊接研究

在对结构钢 (40Cr)同材、结构钢 (40Cr)与工具钢 (T1 0A、GCr1 5 )异材实施恒温超塑性固相焊接可行性全面分析的基础上 ,通过对结构钢、工具钢待焊面表层实施高频淬火组织超细化处理 ,在非真空、无保护气氛下 ,系统地探讨了恒温超塑性固相焊接工艺参数对接头质量的影响 .试验结果表明 :只要选择适宜的焊接工艺参数 ,经短时间压接可使接头强度达到或接近 40Cr母材的强度 ,实现钢的同材和异材恒温超塑性固相焊接 .     

超塑焊接接头变形特点分析

本文以结构钢 (4 0Cr)与工具钢 (T1 0A)为研究对象 ,探讨了两种压前组织超细化预处理工艺 (整体循环淬火和高频淬火 )及压接工艺因素对恒温超塑焊接头变形的影响。试验结果表明 :恒温超塑焊接属小变形焊接 ,其接头变形主要表现为应变的时间积累。压前组织越细 ,其接头变形越大 ,与 4 0Cr侧相比 ,T1 0A侧接头变形均较大     

45钢与40Cr钢焊接工艺研究

本文着重介绍了45钢与40Cr钢的焊接特点,焊接工艺的选择,试验条件及所采用的焊接工艺,并对试验结果进行了分析,表明45钢与40Cr钢选择合理的焊接工艺和方法,对焊后的接头性能相当于45钢退火状态下的机械性能,能够用于公司的批量焊接生产。     

40Cr钢焊接区表面高频淬火后的超塑焊接

探讨了４０Ｃｒ钢焊接区表面局部高频淬火后超塑焊接的可行性及影响因素，并对接头组织进行了观察和分析。试验结果表明，焊接区局部高频淬火后的４０Ｃｒ钢在其超塑变形温度及应变速率范围内，经短时超塑压接其接头抗拉强度可达到母材之值。     

Superplastic Solid-Phase Welding of 40 Cr-T10A Steel

The microstructure of 40Cr and T10A steel sample and its surface to be welded is ultra-fined through salt-bath cyclic quenching and high frequency hardening, then the surface is cleaned. Under non-vacuum and no shielded gas, the welding parameter of isothermal superplastic solidphase welding and the effect of surface microstructure prior to pressure welding on the quality of joint are studied. At the temperature of 730~750℃ and at initial strain rate of (2~4) × 10-4 s-l, the strength of the joint is up to or close to that of 40Cr base metal in 3-5 min pressure welding     

Cr12MoV钢焊接区表面高频淬火后的超塑性焊接

对Cr12MoV钢进行表面高频淬火后超塑性焊接,选用的工艺参数为:加热温度为800℃,焊接时间t=5min,预压应力σ0=56.6MPa,初始应变速率ε0=2.5×10-4s-1。对接头组织进行了观察和分析。试验结果表明,焊接区局部高频淬火后的Cr12MoV钢在其超塑变形温度及应变速率范围内,经短时间超塑焊接,其接头抗拉伸强度可以达到母材值。     

Microstructural evolution of tool steels after Nd-YAG laser repair welding

The present paper is aimed at investigating the microstructural behaviour of tool steels after repair welding or refurbishing by a pulsed Nd-YAG precision laser. The 1.2311 (40CrMnMo7), 1.2083 (X42Cr13) and 1.2343 (X38CrMoV5-1) steels were selected for experimental investigations to cover a wide range of steel grades, commonly used in tooling industry.Laser repair welding condition was simulated by preparing small deposits in one or more passes on steel samples having several reference geometries. Investigations on microstructural properties, microhardness evolution and on defect formation were carried out. The effects of different laser welding parameters were also considered.The study allowed to state several fundamental information on tool behaviour during repair welding in order to gain a deeper insight into this process, routinely considered in industrial practice but often neglected in scientific research works on welding metallurgy.     

不锈钢06Cr19Ni10和碳素钢Q235异种钢埋弧焊焊接工艺研究

根据生产过程中不锈钢06Cr19Ni10和碳素钢Q235-B异种钢板材的埋弧焊焊接问题,结合产品的结构特性和两种材料的焊接性,分析探索了异种钢材焊接的工艺方法,制定了切合实际生产的工艺方案,解决了生产成本高的难题。     

Prediction of residual stresses in welds of similar and dissimilar steel weldments

The fabrication of structural member using dissimilar steels renders steel structures lighter and more economical. However, it always involves welding process and produces different residual stresses in welds as compared with welding of similar steels. This paper presents the characteristics of residual stresses in welds of similar and dissimilar steel weldments by carrying out three-dimensional (3-D) thermal elastic-plastic finite element (FE) analysis. The materials used in this investigation were SM400, SM490, SM520 and SM570, widely used structural steels in welded structure. Results show that the maximum longitudinal residual stresses in welds of the similar steel weldments increase with increasing yield stress of the steel welded (SM400 < SM490 < SM520 < SM570). In case of the dissimilar steel weldments, the difference between the longitudinal residual stresses in welds increases with increasing yield stress of the steel welded together with SM400 (SM490 < SM520 < SM570).     

Characterizations of 21-4N to 4Cr9Si2 stainless steel dissimilar joint bonded by electric-resistance-heat-aided friction welding

A new welding process, electric-resistance-heat-aided friction welding (ERHAFW), was introduced in this study. To further improve the joint quality and energy-saving, electric resistance welding was combined with the conventional continuous-drive friction welding. 21-4N (austenitic stainless steel) and 4Cr9Si2 (martensitic stainless steel) valve steel rods of 4 mm diameter were used as base metals. The results show that electric-resistance-heat-aided friction welding can be applied to join thin rods within a relatively short time, which is very difficult for conventional friction welding (FW). The microstructure of ERHAFW bonded 21-4N to 4Cr9Si2 presents non-uniform across the joint. Different structure zones are observed from the weld line to both sides, which are the weld center, thermo-mechanically affected zone (TMAZ) and heat affected zone (HAZ). These regions exhibit different structures owing to the difference in the thermophysical and mechanical properties of these two steels under the fast heating and cooling during welding. The variation of microhardness in the joint is attributed to the microstructure change. The higher microhardness is obtained in the weld center and TMAZ of 4Cr9Si2 corresponding to the presence of fine tempered martensite and carbides.     

Influence of chromium on superplasticity in ultra-high carbon steels

The influence of chromium additions to ultra-high carbon steels has been investigated. A common bearing steel (52100 containing 1% C and 1.5% Cr), a 1.6%+1.5% Cr steel (designated 52160) and a plain 1.6% C steel have been compared. Chromium is found to enhance greatly the superplastic properties. This is because the chromium enters the cementite and thereby stabilizes it. This in turn allows very little grain growth in ferrite to occur during superplastic deformation. A value of 1220% elongation to failure in 52160 was found at 650° C at an initial engineering strain rate of 1% min^?1. The influence of strain rate on the elongation to failure has also been investigated in this material.     

模具钢表面热喷熔层的超塑性扩散焊接

在 3Cr2W 8V模具钢表面进行了Ni6 0自熔性合金粉末氧 乙炔火焰热喷熔处理 ,并对喷熔层进行了超塑性压缩试验。能谱分析和性能试验表明 ,超塑性扩散焊增大了扩散层深度 ,与未经超塑性压缩的Ni6 0喷熔试样相比 ,经超塑性压缩的喷熔层的抗摩擦磨损性能得到了很大的提高     

含Cu抗菌不锈钢的工艺与耐蚀性能

与普通0Cr17铁素体不锈钢和0Cr18Ni9奥氏体不锈钢相比，含铜铁素体和奥氏体抗菌不锈钢均具有良好的冷热加工性能和焊接性能．通过提高浇铸温度，抗菌不锈钢能保持良好的铸造性能．奥氏体抗菌不锈钢的抗应力腐蚀性能比0Cr18Ni9不锈钢有很大的提高，而铁素体抗菌不锈钢比0Cr17有明显的下降．与相应的普通不锈钢相比，两种类型抗菌不锈钢的耐点蚀性能均略有下降．     

TP304H与12Cr1 MoV锅炉管异种钢的焊接

利用舍夫勒组织图对韶关发电厂SA2 13TP30 4H与 12Cr1MoV异种钢接头可能出现的焊接组织进行了分析 ,制订出了合理的焊接工艺 ,并对锅炉上的SA2 13TP30 4H与 12Cr1MoV钢焊口进行了施焊 ,经 17个月的运行 ,10 4个焊口未出现爆漏现象     

铁素体-珠光体型非调质钢的高周疲劳破坏行为

研究了三种碳和钒含量不同的铁素体-珠光型非调质钢的高周疲劳破坏行为,并与调质钢进行了对比.结果表明,铁素体-珠光体型非调质钢的高周疲劳性能与其微观组织特征有关.提高铁素体相硬度,其疲劳极限及疲劳极限比均提高,疲劳极限比最高可达0.60,远高于调质钢的0.50;热轧态粗大的网状铁素体-珠光体组织的疲劳性能较差,低于同等强度水平的高温回火马氏体组织。铁素体-珠光体型非调质钢疲劳破坏机制不同于调质钢,其疲劳裂纹基本上萌生于试样表面的铁素体/珠光体边界,并优先沿着铁素体/珠光体边界扩展;对于同等强度水平的调质钢,不存在像铁素体那样的软相,因而易在试样表层粗大的夹杂物处萌生疲劳裂纹.     

Microstructures and mechanical properties of welded joints of novel 3Cr pipeline steel using an inhouse and two commercial welding wires

The welded joints of the novel 3Cr pipeline steel were fabricated via the gas tungsten arc welding (GTAW) technique using an inhouse welding wire labeled as R01 and two kinds of commercial wires (H08Cr3MoMnA and TGS-2CML). Microhardness, impact toughness and tensile properties of the joints were measured, and microstructure characteristics were observed by scanning electron microscopy (SEM). The results show that under selected welding procedure, the joints of R01 can achieve quite good mechanical properties without preheating and post weld heat treatment (PWHT). After thermal refining, elongation (15.2%) doubled and met the DNV-OS-F101 standard. For low carbon or super low carbon pipeline steels such as 3Cr steel, the revised formula with the carbon applicable coefficient (A(c)) was quite good for predicting the maximum hardness in heat affected zone (HAZ). Compared with these two selected commercial wires, the inhouse welding wire R01 can provide the highest cost-performance ratio.     

Uniaxial ratchetting in steels with different cyclic softening/hardening behaviours

The cyclic deformation of three structural steels, SS316L stainless steel, 40Cr3MoV bainitic steel and 25CDV4.11 steel, were studied experimentally by uniaxial cyclic straining or stressing tests at room temperature. The cyclic softening/hardening behaviours of the steels were discussed first by cyclic straining tests; and then the effects of cyclic softening/hardening behaviours on the uniaxial ratchetting of the materials were investigated by asymmetrical cyclic stressing tests. It is concluded from the experimental results that the ratchetting greatly depends on the cyclic softening/hardening behaviours of the materials, as well as the loading history. Different ratchetting and failure behaviours are observed for the prescribed steels. It is also stated that the proposed unified visco‐plastic constitutive model can provide a fairly reasonable simulation of the uniaxial ratchetting of SS316L stainless steel and 25CDV4.11 steel; but cannot simulate the ratchetting of 40Cr3MoV bainitic steel since the dependence of cyclic softening behaviours on the applied inelastic strain amplitude cannot be reasonably described in the discussed constitutive model. Some significant conclusions are obtained, which are useful to construct constitutive model to describe the ratchetting of the materials with different cyclic softening/hardening behaviours.     

Deformation and microstructure evolution of a duplex stainless steel under out-of-phase thermo-mechanical fatigue

Abstract

Thermo-mechanical fatigue (TMF) of the duplex stainless steel SAF2205 (X2CrNiMoN22-5-3) was studied in the temperature range of 100–350°C. The tests were carried out on the duplex steel and on single-phase ferritic (X6Cr17, AISI 430) and austenitic steels (X2CrNiMo18-14-3, AISI 316L) similar to the two phases of the duplex steel for comparison. The mechanical behaviour of the three steels is analysed and discussed together with microstructural investigations by scanning electron microscopy, including electron backscatter diffraction and electron channelling contrast imaging.     

底注钢锭模设计及特种Cr-Ni、Cr-Mo钢锻件的试制

指出了Ｃｒ Ｍｏ钢、Ｃｒ Ｎｉ钢等特种钢锻件生产中存在的工艺问题。设计了专用的底注钢锭模,试制出符合ＡＳＴＭＡ１８２－７８标准要求的Ｃｒ９Ｍｏ、１．２５Ｃｒ０．５Ｍｏ、Ｃｒ２５Ｎｉ２０钢锻件,解决了这些特种钢的原材料供应难题。