En studie av hur olika parametrar påverkar sträckgräns och hårdhet under kallvalsning
Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
This study concerns different quality parameters in cold pilgering of seamless steel tubes. Three steel grades have been examined. The aim of the study is to increase the knowledge regarding the process and present statistical support for what factors affect the yield strength, hardness and variation in hardness of the steel during cold pilgering. The independent variables are area reduction, reduction mode, pilger mill, and tool’s design. Secondary data from a steel producing company has been used to evaluate the relevant factors. The relationships between dependent and independent variables have been studied by plotting and regression analysis.The analysis resulted in several statistical models that explain the various connections. The analysis shows that all explanatory variables have a positive effect on the hardness of the material for two steel grades. The yield strength also depends on several variables. The analysis of the third steel grade suffers from lack of data; therefore these models do not get as high a coefficient of determination. A discussion about validity and reliability follows throughout the study. Different weaknesses in the parameters have been detected and several suggestions on improvements have been presented. Finally the report contains reasoning about alternative methods and how the study can be further developed. Since the competition in the steel producing business is severe, the company has chosen not to publicize the results of the study further. Hence this abstract is the only thing published.
Place, publisher, year, edition, pages
2013. , 73 p.
Teknik, Kvalitetsteknik, regressionsanalys, kallvalsning
IdentifiersURN: urn:nbn:se:ltu:diva-54772Local ID: bb34d6ec-bc36-433b-a1d1-987cd266b987OAI: oai:DiVA.org:ltu-54772DiVA: diva2:1028154
Subject / course
Student thesis, at least 30 credits
Industrial and Management Engineering, master's level
Validerat; 20130412 (global_studentproject_submitter)2016-10-042016-10-04Bibliographically approved