Effect Of Sulfide Inclusions Research Articles

Failure Analysis of Friction Weld in Rear Axle Casing

In this study, Housing and Spindle failed at Friction weld (FRW) interface and sample submitted was from a Passenger vehicle after covering 18410 Kms was considered to address the repeated weld failures reported in Rear Axle Casing. The Metallurgical examinations revealed, chemical composition and hardness found satisfactory whereas Microstructure reveals presence of MnS (Manganese Sulphide) Inclusions at the friction weld interface resulting in insufficient friction weld fusion.SEM and Metallographic examinations confirmed the Orientation of MnS (Manganese sulphide) along the surface of the Spindle that was subjected to Friction welding (FRW) resulting in insufficient weld fusion. Microstructure observation of Spindle shows inclusions of Type A - Thick 2 against the allowable limits in Raw Material Type A - Thick 1. Also, the elongated MnS inclusions at the Friction weld (FRW) Interface act as initiation sites, "Stress raiser "that is more vulnerable to failure due to comparatively less tensile and impact strength than base metal similar to the effect of flake graphite’s in cast iron. Due to the anisotropy and orientation of the sulfide inclusions there is reduction in transverse ductility in reduced area and not much significant effect in longitudinal direction. Inclusion control by calcium treatment or Electro slag re-melting in spindle raw material will significantly improve the ductility and toughness of friction weldments. This paper aims to study the effect of Sulfide inclusions on weldability, mechanical properties of weld Interface and role as fracture initiation site.

Microscopic Evaluation of a Damaged Press Casing and Analysis of Failure by Finite Element Method

The paper presents an instance of a failure of the casing of a press used to make hexagonal clamps on tubes used in power engineering. The failure occurred during the press operation. The results of microscopic investigations of the cracked area show that the crack was initiated by excessive accumulation of sulfide inclusions with an unfavourable banded structure that formed in the steel. An EDS analysis identified MnS involved in the crack mechanism.Moreover, an FEM simulation of the pressure distribution and an annulus model of axial loading were used to analyse the stress and strain values arising in the press casing under compression. It was found that normal compressive stresses in direction Z were much larger in the region where the crack occurred, which means that the press casing mechanical manufacturing process creates the largest stresses in the fillet radius area. On the other hand, the effect of sulphide inclusions in the material were also considered as a cause of failure.It is concluded that both these factors – equivalent stresses and the high level of sulphide inclusions in the steel structure have an impact on the press casing failure.

Real time pit initiation studies on stainless steels: The effect of sulphide inclusions

It has long been accepted that manganese sulphide favours pitting on stainless steels. However, there are different standpoints on the most important mechanism for pit initiation; due to dissolution of sulphide inclusions, chromium depletion around the inclusion or mechanical rupture of the passive film by metal chlorides. Analysing the pitting potential and metastable pitting rates on different grades of stainless steels has rationalised the effect of sulphide content on pitting corrosion resistance. In situ atomic force microscopy (AFM) has been used in conjunction with conventional electrochemical techniques for imaging real time pit initiation events.

Effect of sulfur on the fractographic characteristics of failure for low-carbon low-alloy steel

1. An increase in hot-rolled ferrite-pearlite steel 09G2 of sulfur content from 0.007 to 0.040 wt.%, causing an increase in the volume fraction of sulfide inclusions ((0.37...2.12)·10−3) with an almost constant size, leads to an increase by approximately a factor of two in the brittle zones of fractures of the proportion of intercrystalline failure due to segregation of sulfur along ferrite and pearlite grain boundaries, and by a factor of two to ten in the proportion of pitting failure connected with formation of pits at large MnS particle inclusions. The degree of the effect of sulfide inclusions on the proportion of pitting failure increases with a reduction in test temperature from −20 to −60°C. 2. In the transition temperature range (Ttest=−20°C) an increase in the steel of sulfide volume fraction (by a factor of 5.5) does not markedly affect the nature of leading TC microcrack distribution at the tip of a large microcrack: they propagate predominantly counter to a brittle macrocrack. The effect of sulfide inclusions on the nature of leading microcrack distribution becomes marked with a reduction in test temperature to −60°C when the proportion of pitting failure in the brittle fractures of specimens of test steel containing 0.007–0.040 wt.% sulfur differs by a factor of ten due to a marked increase in the proportion of counter leading TC microcracks in the steel with an increase in sulfur content. 3. A tendency is detected towards an increase in ferrite grain size with an increase in sulfur content from 0.007 to 0.040 wt.% in steel 09G2. An increase in volume fraction of sulfides (0.37...2.12)·10−3 does not affect the frequency of TC microcrack generation in ferrite grains.

Wear resistance of quenched and tempered AISI 4137H steel

Abrasive wear resistance of quenched and tempered AISI 4137H steel was studied using the dry sand/rubber wheel test. The variables studied included hardness, tempering temperature, and cleanliness of the steel. The effect of sulfide inclusions on the relative wear performance of the steel was examined. Debris from the wear tests was analyzed using SEM and sieve analysis. The effects of steel cleanliness and sulfide inclusion shape on abrasion resistance are explained in terms of the relative ease for chip formation and its subsequent detachability during the abrasion process.

Effect of various sulfide stringer populations on the ductility of hot-rolled CMn steels

The effect of sulfide inclusions on anisotropy of axisymmetric and plane-strain fracture strain was investigated in three 0.1% C, 1.0% Mn steels containing 0.004, 0.021, or 0.028% S. The effect of the sulfide inclusions on axisymmetric and plane-strain fracture strain correlated with the projected area of inclusions per unit volume, A r , or the mean local area fraction of inclusions on a plane perpendicular to the tensile direction regardless of tensile direction: transverse or through thickness. The magnitude of A r was orientation dependent and was directly proportional to the volume fraction of inclusions and inversely proportional to the inclusion dimension parallel to the tensile direction. Dirichlet cell tessellation procedures were used to calculate local area fractions of inclusions, nearest-neighbor distances, and near-neighbors distances on longitudinal, transverse, and through-thickness planes. The mean local area fraction of inclusions was orientation dependent and was significantly larger than the total area fraction. The mean nearest-neighbor and near-neighbors distances were also dependent on orientation. The near-neighbors distances were incorporated into a simple anisotropic model of ductile fracture which gave good agreement with the observed fracture strains for both transverse and through-thickness specimens.

Effect of shape of sulfide inclusions on anisotropy of inclusion spacings and on directionality of ductility in hot-rolled C-Mn steels

The effects of sulfur content (0.004 or 0.013 pct) and sulfide morphology (stringered or globular) on anisotropy of tensile ductility and Charpy shelf energy were investigated in a series of 0.1 and 0.2 pct carbon, 1.0 pct manganese steels. The effect of sulfide inclusions on fracture strain or Charpy shelf energy correlated with the projected area of inclusions per unit volume,Av, on a plane perpendicular to the tensile direction and the mean free distance between inclusions, λ, in a direction parallel to the tensile direction regardless of the amount or the shape of the inclusions or the test direction: longitudinal, transverse, or through-thickness. The magnitude ofAv is directly proportional to the volume fraction of inclusions and inversely proportional to the inclusion dimension parallel to the tensile direction. The mean free distance, λ, is inversely proportional toAv. Approximate relations were obtained for the nearest-neighbor distances between inclusions on the longitudinal, transverse, and through-thickness planes. These distances were incorporated into a model for ductile fracture based on an adaptation of a previously proposed criterion for the linkage of voids nucleated at second-phase particles. The agreement between the observed and predicted fracture strains for longitudinal, transverse, and through-thickness specimens of the steels studied is encouraging.

Effect of Sulfides and Sulfide Morphology on Anisotropy of Tensile Ductility and Toughness of Hot-Rolled C-Mn Steels

The effects of sulfur content (0.004 or about 0.013 pct) and sulfide morphology (stringered or globular) on anisotropy of tensile ductility and Charpy V-notch (CVN) shelf energy were investigated in a series of 0.1 and 0.2 pct carbon, 1.0 pct manganese steels. The effect of sulfide inclusions on fracture strain or CVN shelf energy correlated with a single parameter,P, regardless of inclusion shape, stringered or globular, or test direction, longitudinal, transverse, or through-thickness. The parameterP was defined as the total projected length of inclusions per unit area on a plane parallel to the fracture plane. The fracture strain and CVN shelf energy decreased with an increase inP. The magnitude ofP was directly proportional to the volume fraction of inclusions and inversely proportional to the inclusion dimension perpendicular to the fracture plane. The lower tensile ductility and CVN shelf energy in the 0.2 as compared with the 0.1 pct carbon steels was a consequence of the greater pearlite content in the former steels. This greater pearlite content had no apparent effect on the work-hardening rate,H, but decreased the strain-rate sensitivity of the flow stress,M, and the strain-rate sensitivity of the work-hardening rate,B. The decrease inM andB with increasing pearlite content is in accord with a decrease in tensile ductility according to recent models of neck development in tension tests. It appears that the decrease in tensile ductility with increasing pearlite content is a result of enhanced localized shearing, which promotes the coalescence of voids nucleated at second phases.

The effect of sulphide inclusions on fracture toughness and fatigue crack growth in 12 wt% Cr steels

The variation of plane strain fracture toughness and fatigue crack growth rates with sulphide inclusion content has been examined for four different sulphur levels in a 12 wt% Cr stainless steel. Charpy impact tests have also been conducted and the experimental results are correlated with the volume fraction of inclusions and the inter-inclusion spacing. The availability of the experimental results for the case of steam turbine blading is discussed with a hypothetical example problem.

The effect of sulfide inclusions on the susceptibility of steels to pitting, stress corrosion cracking and hydrogen embrittlement

AbstractRecent opinions on the effect of nonmetallic inclusions, especially sulfides, on the nucleation of pits, stress corrosion cracks, and hydrogen‐induced cracks are reviewed.The nonmetallic inclusions present in steels as impurities adversely affect the corrosion resistance of steels. This is true for both the general and local corrosion mechanisms, like pitting corrosion, stress corrosion cracking (SCC), and hydrogen embrittlement (HE).The effect of nonmetallic inclusions (in particular that of sulfides) on the pitting corrosion mechanism has been the subject of numerous investigations. A fairly aboundant information can be found in vast original literature and in many review articles [1–3]. The role of nonmetallic inclusions in SCC is relatively less covered in the pertinent literature. Since, however, the nucleation of corrosion cracks frequently starts from pits, and pits nucleate at sulfides, the presence of sulfides is likely to affect the SCC process.Another corrosion mechanism that leads to a local cracking of a metal is the hydrogen embrittlement. The presence of nonmetallic inclusions enhances susceptibility of steel to hydrogen‐induced cracking [4].This review will be concerned with the effect of nonmetallic inclusions on the local corrosion types mentioned.

Effect of sulphide inclusions in a commercial stainless steel on the nucleation of corrosion pits

As shown by electron microprobe investigations, corrosion pits in a commercial austenitic 18%Cr-9%Ni steel are initiated at the mixed manganese and iron sulphide inclusions.