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一、前言在含有V,Ti,Nb的许多钢种中,都存在着晶粒不匀现象,关于造成混晶的原因,尚在研究中。高压锅炉管材技术标准YB-529-70中规定,管材实际晶粒度检查是在一个视场中晶粒度级差不得大于3级,做为出厂和验收的技术条件。对这一技术要求在较长时间内引起很多争论。在我厂实际检验中,常发现在一个管子检验样上,选一个视场检查晶粒度级差不大于3级,可在几个视场上检查晶粒
I. Preface In many steels containing V, Ti, Nb, there is a phenomenon of grain unevenness. The reason for the mixed crystal is still under study. High-pressure boiler pipe technology standard YB-529-70 stipulates that the actual grain size inspection is in a field of view of the grain size difference of not more than 3, as the factory and acceptance of the technical conditions. The technical requirements for a long time caused a lot of controversy. In our factory actual inspection, often found in a tube test sample, choose a field of view of grain size difference is not more than 3, in a few fields of view check the grain