Improving the production of pipe steel

Melts of pipe steel (strength class K52) obtained at the casting and rolling complex of AO OMK (a branch of AO OMK-Stal’) are analyzed. The initial data correspond to a set of 30 melts. The production system includes batch preparation, steel production in an arc furnace, treatment in a ladle–furnace unit, vacuum treatment (with microalloying and modification), hot rolling, and cutting of the rolled steel into sheet and strip. The basic factors affecting steel quality are identified. The rejection of the steel produced is mainly due to brittle and undeformable nonmetallic silicate inclusions. Changes in the process so as to reduce the content of nonmetallic silicate inclusions are recommended.     

Improving the production of cold-rolled steel

The influence of the basic technological factors on the loss of strip width in cold rolling is considered. The influence of technological factors and the state of the working rollers on the formation of light bands (impressions) at each working roller in the first cell of the old-rolling mill is investigated. Means of eliminating these problems in the production of cold-rolled steel are proposed.     

Special features of the production of low-alloy powder steel for structural and antifriction purposes

Conclusions The use of a minimal amount of plasticizer (not more than 0.5%) in the compacted charge and molds with additional drainage make it possible with a single compaction and sintering to obtain highly dense powder products — (7.2-7.3)·10³ kg/m³ — with a compacting pressure of 1000 MPa. Sintering of highly dense powder material ZhGr0,8D2N1 for 3.6 ksec is accompanied by its decompaction in consequence of degassing; extending the sintering time to 10.8 ksec reduces the porosity and improves the mechanical porperties of the products.The combination of the processes of sintering and hardening of rollers made of powder steel ZhGr0,8D2N1 in the plant Degussa makes it possible to obtain great hardness (of the order of 50–53 HRC) of products with a porosity of 5–10% after their cooling in oil. In comparison with existing technological processes, this one is distinguished by high productivity and degree of automation and mechanization; all this meets perfectly the requirements of mass production.Study of the refrigerating capacity of compressors confirmed the possibility of successfully using porous components operating in dynamic regimes under conditions of liquid lubrication, using capillary phenomena and the effect of hydraulic obliteration of fine communicating pore channels for lubricating the surfaces of friction pairs.Translated from Poroshkovaya Metallurgiya, No. 9(297), pp. 42–47, September, 1987.     

Improving the production of superthin anisotropic electrical steel

Electrical steel with scattered ribbed texture may be used as the initial material in the production of superthin anisotropic electrical steel with perfect (110)[001] texture by the Littmann method. The possibility of producing superthin anisotropic electrical steel with 0.5 wt % Cu is demonstrated.     

Effective rough rolling of low-alloy steel

The behavior of surface defects in continuous-cast slabs is investigated during rough rolling. A model of the change in defect shape is developed, and recommendations are made regarding the prevention of crack motion toward the strip axis.     

低合金钢中总化合氮的测定

介绍了低合金钢中总化合氮的测定方法。首先利用 5 g/L的柠檬酸和 5.0g/L氯化钾水溶液进行电解 ,然后溶解电解残渣 ,再蒸馏滴定 ,测定电解残渣中的总化合氮。该方法易于操作 ,实用性强 ,精密度和准确度都达到要求 ,为提高钢材性能研究提供了依据。     

Predicting the ferrite grain size in low-alloy steel

Mathematical models are proposed for calculating the onset temperature of ferrite transformation and the ferrite grain size as a function of the cooling conditions and the initial austenite grain size. The models are calibrated on the basis of experimental data for steels with ferrite-pearlite microstructure. The models are integrated in HSMM software, with considerable gain in computational power when considering the mechanical properties of steel rolled on the 2000 mill at OAO Severstal??.     

Tempering behaviour of a dual-phase low-alloy steel

The tempering behaviour of a dual phase steel of 0.08% C, 1.21% Mn, 1.00% Si, 0.42% Cr, and 0.41% Mo composition with two different martensite contents of 30 and 52%. (obtained by intercritical treatments at 820 and 860°C, respectively) has been studied. The ultimate tensile strength decreased and percentage elongation increased continuously with increasing tempering temperature up to 600°C for both intercritical treatments. The yield strength has, however, increased up to 300°C, beyond which it decreased for the steel with 30% martensite. In contrast it remained almost constant for 52% martensite up to 300°C, beyond which it decreased. The martensite of dual-phase steel for both the intercritical treatments has undergone microstructural changes on tempering that are akin to those of fully martensitic low carbon steels. The SEM fractographs from the as-quenched specimens indicate that the tensile specimens failed by microvoid coalescence with the martensite areas appearing facetted and featureless while those for 600°C tempered condition by the formation of equiaxed dimples.     

Microstructure in low-carbon low-alloy high-strength pipe steel

The microstructure of a broad range of low-carbon low-alloy high-strength pipe steels produced by thermomechanical treatment is studied by transmission electron microscopy. Such steels consist of a mixture of various types of ferrite matrix with high-carbon phases and structural components. The classification of the structures is refined, with separate consideration of the components forming the low-carbon ferrite matrix and the high-carbon components that appear as isolated regions and also as layers and inclusions in bainitic ferrite. A deformational dilatometer is used to determine the temperatures ranges in which the various phases and structural components are formed.