THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON

The Design and Analysis of Experiments

Welding science and technology

Cooling rate of the weld during solidification has significant influence on metallurgical and mechanical properties of welded joint. In the present study, cooling rates have been predicted during electron beam welding of AISI 304 stainless steel for different values of energy input per unit length using physics-based phenomenological model and commercial finite element analysis. Cooling rates predicted by the above models have been validated with the experimental cooling rate estimated indirectly from the secondary dendritic arm spacing (SDAS) obtained in the microstructure of the welded sample. The predicted cooling rate is observed to vary inversely with the energy input per unit length, as expected. It has also been correlated with the grain characteristics like grain size and grain boundary character distribution (GBCD) obtained by EBSD analysis of the weld metal. An increase in low-angle boundary has been observed with the increase in cooling rate, which has been attributed to an increase in dislocation density.

Cooling rate predictions and its correlation with grain characteristics during electron beam welding of stainless steel

Influence of the interpass temperature on t8/5 and the mechanical properties of submerged arc welded pipe

The weldability of carbon steel is determined by carbon equivalent (CE) for predicting/estimating preheat temperatures necessary for weld integrity of the weldment. The microstructure of the welded...

A review of weldability of carbon steel in arc-based welding processes

An experiment based thermal analysis has been performed to obtain the thermal histories, which can be applied to determine cooling rate of weldment. During fusion welding process it is possible to determine temperature at any point by using thermocouple and from such data it is possible to draw thermal histories for any point of interest, such thermal histories can be utilized to determine cooling rate. The temperature distribution and cooling rate during the welding process have significant effect on the mechanical and metallurgical properties of a weldment. The changes in microstructure, grain growth and hardness in a weldment are very dependent on the temperature distribution and cooling rate. These studies are utilized to investigate the micro-structure and microhardness of the heat affected zone (HAZ) and weldment. In present work, the influence of heat input and cooling rate on microhardness has been investigated. Full factorial design is used to conduct the experiment with three factors and two levels. Eight combinations and two set of heat input are designed with different combinations of SAW welding parameters. Temperature distribution curves and cooling rate have been drawn. The effect of selected welding parameters (Wire feed rate, Open circuit Voltage and welding Speed) on the microhardness have been investigated.

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Rahul Kumar

Papers

Experimental Determination of Cooling Rate and its Effect on Microhardness in Submerged Arc Welding of Mild Steel Plate (Grade c-25 as per IS 1570)