自动变光焊接护目镜响应特性测试仪研究

为制定变光焊接护目镜新产品专业标准提供支撑，进行了焊接弧光特性和变光焊接护目镜响应特性研究，解决了焊接弧光模拟、弧光信号检测、时间小信号检测等技术关键，研制了响应特性测试系统，并进行实测分析。便携式测试仪采用暗箱全封闭结构，能产生模拟的交直流弧焊信号，能检测10^-1～10^4lx照度的光信号并保持线性，能检测弧光作用下护目镜可见光透射比的整个变化过程，最大采样频率达30kHz，确保测试精度，能按响应时间定义进行记录和运算，测试接口具有通用性。     

Enhancement of UV and chromate mutagenesis by nickel ions in the Chinese hamster HGPRT Assay †

1. The HGPRT (Hypoxanthine‐Guanine‐Phospho‐Ribosyl‐Transferase) assay with Chinese Hamster V79 cells was used to measure the mutagenic effects of UV irradiation, potassium dichromate and nickel chloride. The agents were tested separately and in the combinations of UV plus nickel and dichromate plus nickel.

2. UV, Cr(VI) and Ni(II) were confirmed to be mutagenic in the V79 cell assay. The combination of UV(5J/m²) and Ni(II) (0.5 mM) caused a mutation rate 11.2 times above that corresponding to the sum of the individual mutation rates of these agents. The combined action of Cr(VI) (0.1 mM) and Ni(II) (0.5 mM) produced a mutation rate 2.8 fold above that corresponding to the sum of the individual rates of the separate agents.

3. The enhancing effect of nickel chloride on the mutagenicity of UV or Cr(VI) is interpreted by an interference of Ni(II) with the repair of DNA lesions.     

The controlled short circuit GMAW process: A tutorial

The paper reviews the principles, benefits and limitations of the conventional short circuit transfer mode in GMA welding before describing the development and benefits of the controlled short circuit approach. Various options are described and an attempt is made to categorize the current commercial systems.     

Emissions of fluorides from welding processes

The levels of fluoride airborne particulates emitted from welding processes were investigated. They were sampled with the patented IOM Sampler, developed by J. H Vincent and D. Mark at the Institute of Occupational Medicine(IOM), personal inhalable sampler for simultaneous collection of the inhalable and respirable size fractions. Ion chromatography with conductometric detection was used for quantitative analysis. The efficiency of fluoride extraction from the cellulose filter of the IOM sampler was examined using the standard sample of urban air particle matter SRM-1648 a. The best results for extraction were obtained when water and the anionic surfactant N-Cetyl-N-N-Ntrimethylammonium bromide(CTAB) were used in an ultrasonic bath. The limits of detection and quantification for the whole procedure were 8 μg/L and 24 μg/L, respectively The linear range of calibration was 0.01–10 mg/L, which corresponds to 0.0001–0.1 mg of fluorides per m3 in collection of a 20 L air sample. The concentration of fluorides in the respirable fraction of collected air samples was in the range of 0.20–1.82 mg/m3, while the inhalable fraction contained 0.23–1.96 mg/m3 of fluorides during an eight-hour working day in the welding room.     

PTA锻焊反应器的制造

本文对PTA装置上的大型铬钼钢锻焊反应器,在制造过程中的几个关键技术进行了介绍：控制材料的化学成分提高铬钼钢材料的抗回火脆化能力;采用先进的冶炼工艺和锻造技术保证大型锻件的质量;优化铬钼钢封头正火热处理中的冷却工艺来保证材料的性能指标;采用合理的焊接工艺,既保证了厚壁环焊缝的焊接质量,又降低了制造成本;优化堆焊工艺,保证了反应器内壁的堆焊质量;正确选择热处理规范,对铬钼钢压力容器至关重要。     

某铁路货车检修车间污染治理分析

某车辆段货车检修中抛丸除锈、电焊、喷漆、探伤等工艺存在粉尘颗粒物、有机废气等职业危害因素.检测表明,电焊烟尘产生的粉尘颗粒物为主要污染源,急需治理.通过改造设置下送上回式的排烟除尘系统,车间污染情况得以有效改善,经检测室内粉尘满足工作场所有害因素职业接触限值要求,颗粒物排放满足国家环保标准要求.     

Welding processes for wear resistant overlays

This paper presents a comprehensive survey of welding processes used to deposit wear resistant overlays. It is based on both literature review and research work performed at the Canadian Centre for Welding and Joining. The focus is on the two most popular material systems used for wear resistant overlays: nickel-base with the addition of tungsten carbide particles, and iron-base in which chromium carbides of the form M₇C₃ nucleate during solidification. The processes surveyed in detail are plasma transfer arc welding, submerged arc welding, laser beam welding, gas metal arc welding-related processes using tubular wires, oxy-acetylene flame brazing, and the still-experimental applications of friction stir processing. Cost and market are key factors influencing technical decisions on wear protection overlays, but the information is scarce and often tightly guarded. An informal survey from our industrial partners is included.     

箱形长钢梁内焊接危害分析与对策

大跨度起重机箱形梁,因结构强度的要求,需要从两端进入梁内施焊。由于截面小、长度大,作业中产生大量烟尘、毒气,不能及时排出,严重损害工人身体健康。特别在高温季节,焊接热又使梁内温度增高,操作者闷热难忍,危害身心健康,影响工作效率。本文在实验研究基础上,分析了箱形长钢梁内多人焊接时,产生的烟尘、毒气及其分布情况,并“以人为中心”,剖析各种解决焊接危害技术的特点,提出适用于截面在1～2m~2、长度在30～50m范围的钢梁内多人施焊时的排烟降温对策。     

焊接工程质量与焊接工程文件

焊接质量只能是过程控制作为国际焊接标准体系中的核心标准ISO 3834给出过程控制手段就是焊接工程文件对不同质量等级对应的文件要求不同,等级越高的焊接产品,其过程控制的文件也越多,控制点更细,保证产品达到高品质要求.与之对比某事故工程的反例,该工程的焊接文件漏项多,过程控制不能保障焊接工程的安全.通过对比国际标准,发现由于国内产品焊接标准不够成熟,没有规定产品GB/T 12467质量等级(类似ISO 3834-2,3,4),因此文件分级欠专业要求.焊接制造业升级必然是标准先行,焊接标准明确质量等级,焊接工程文件体系也将完善,从而为保障焊接工程的安全运行保驾护航.     

A comparative study on the effect of GTAW processes on the microstructure and mechanical properties of P91 steel weld joints

Modified 9Cr-1Mo (P91) steel is widely used in the construction of power plant components. In the present study, a comparative study on influence of activated flux tungsten inert gas (A-TIG), and gas tungsten arc (GTA) welding processes on the microstructure and the impact toughness of P91 steel welds was carried out. P91 steel welds require a minimum of 47 J during the hydrotesting of vessels as per the EN1557: 1997 specification. Toughness of P91 steel welds was found to be low in the as-weld condition. Hence post-weld heat treatment (PWHT) was carried out on weld with the objective of improving the toughness of weldments. Initially as per industrial practice, PWHT at 760 °C – 2 h was carried out in order to improve the toughness of welds. It has been found that after PWHT at 760 °C – 2 h, GTA weld (132 J) has higher toughness than the required toughness (47 J) as compared with A-TIG weld (20 J). The GTA weld has higher toughness due to enhanced tempering effects due to multipass welding, few microinclusion content and absence of δ-ferrite. The A-TIG weld requires prolonged PWHT (i.e. more than 2 h at 760 °C) than GTA weld to meet the required toughness of 47 J. This is due to harder martensite, few welding passes that introduces less tempering effects, presence of δ-ferrite (0.5%), and more alloy content. After PWHT at 760 °C – 3 h, the toughness of A-TIG weld was improved and higher than the required toughness of 47 J.