Hydrogen-induced delayed fracture of Cu-containing high-strength bolt steel

The hydrogen-induced delayed fracture(HIDF)behavior of a 1300-MPa-grade high-strength bolt steel 42CrMoV containing 0.42 wt.%Cu was investigated by constant load tensile test in a pH 3.5 Walpole solution.It is shown that the addition of Cu is beneficial to enhance the HIDF resistance by~13%.The observation of the fracture surface revealed that the area fraction of brittle crack initiation zone decreased remarkably for the Cu-added steel.Both the corrosion pit depth and the corrosion rate of the Cu-added steel in the Walpole solution are notably decreased,which is primarily because of the formation of a Cu-rich protective compact rust layer and slightly higher corrosion potential.As a result,the absorbed hydrogen content in that solution was also decreased by~21%.It is concluded that the improvement in the HIDF resistance of the tested steel is primarily due to the increase in corrosion resistance and resultant decrease in the absorbed diffusible hydrogen content in the acidic condition.

Effects of Niobium and Vanadium on Hydrogen-Induced Delayed Fracture in High Strength Spring Steel

Influence of vanadium and/or niobium additions on delayed fracture behavior in high strength spring steel was studied by hydrogen permeation method and slow strain rate technique （8SRT）, and its mechanism was analyzed. The results show that apparent diffusion coefficient of hydrogen in microalloyed spring steels Nb-V-steel and Nb-steel is lower than that in non-microalloyed steel 60Si2MnA. Percentage of strength reduction in SSRT in air after precharged hydrogen of the microalloyed steels is smaller than that of 60Si2MnA. Addition of the microalloys changes the fracture characteristics. Thence, vanadium and/or niobium additions are a very effective and economy means to improve the hydrogen-induced delayed fracture resistance of high strength spring steel.

Study on Fracture Delay of High-Strength Bolts in Road Bridge Maintenance

In the maintenance work of highway and bridge engineering structures,the fracture delay of high-strength bolts is a content that needs to be focused on and researched.Based on this,the paper analyzes the fracture delay of high-strength bolts in highway bridge maintenance,including an overview of the fundamental research on fracture delay and related specific studies.It is hoped that this study can provide scientific reference for the reasonable maintenance of high-strength bolts,so as to ensure the overall maintenance effect of highway bridge projects.

Surgical treatment of an old avulsion fracture of the ischial tuberosity and ischial ramus: A case report

BACKGROUND Avulsion fracture of the ischial tuberosity is a relatively clinically rare type of trauma that is mainly incurred by adolescents during competitive sports activities.According to previous literature,the most commonly involved sports are soccer,sprinting,and gymnastics,in descending order.Dance-induced avulsion fracture of the ischial tuberosity and ischial ramus is extremely clinically rare.CASE SUMMARY A case of a neglected avulsion fracture of the ischial tuberosity and ischial ramus was diagnosed in a young female dancer who complained of pain and restricted movement of her right hip.She stated that she had suffered the injury while performing a split leap during a dance performance 9 mo prior.Eventually,she underwent surgery and obtained satisfactory treatment results.CONCLUSION Early diagnosis of these fractures is important to ensuring early proper treatment towards a quicker recovery.For old fractures with nonunion and chronic buttock pain,surgery is a preferred therapeutic choice with good treatment outcomes.

Delayed Fracture Behavior of CrMo-Type High Strength Steel Containing Titanium

The delayed fracture behaviors of CrMo-type high strength steels containing different amount of titanium(0to 0.10%)were studied.The steels were quenched at 880℃ and tempered from 400℃ to 650℃,and a wide range of tensile strength was obtained.The sustained load tensile test was carried out by using notched tensile specimens in Walpole solution.The experimental results showed that with higher strength,the Ti-microalloyed steels show higher resistance to delayed fracture compared with non-microalloyed steel due to titanium beneficial role and microstructure changes.The undissolved TiC is uniformly distributed as strong hydrogen traps,retarding or preventing the diffusion and accumulation of hydrogen to lower-interaction energy sites,such as prior austenite and martensite lath boundaries in stress concentration area.Meanwhile,the grain refining effect of titanium is also an important factor to improve the delayed fracture resistance of Ti-microalloyed steels.The characteristics of delayed fracture remain nearly the same with titanium addition.

Systematic review of dynamization vs exchange nailing for delayed/non-union femoral fractures

AIM To analyze the literature on efficacy of dynamamization vs exchange nailing in treatment of delayed and nonunion femur fractures.METHODS Ultimately, 31 peer-reviewed articles with 644 exchanged nailing patients and 131 dynamization patients were identified and analyzed. The following key words were inputted in different combinations in order to search the field of publications in its entirety: "nonunion", "delayed union", "ununited", "femur fracture", "femoral fracture", "exchange nailing", "dynaiz(s)ation", "secondary nailing", "dynamic", "static", and "nail revision". The initial search yielded over 150 results, and was refined based on the inclusion criteria: Only studies reporting on humans, non-unions and delayed unions, and the usage of exchange nailing and/or dynamization as a secondary treatment after failed IM nailing. The resulting 66 articles were obtained through online journal access. The results were filtered further based on the exclusion criteria: No articles that failed to report overall union rates, differentiate between success rates of their reported techniques, or articles that analyzed less than 5 patients. RESULTS Exchange nailing lead to fracture union in 84.785% of patients compared to the 66.412% of dynamization with statistically comparable durations until union(5.193 ± 2.310 mo and 4.769 ± 1.986 mo respectively). Dynamically locking exchange nails resulted in an average union time of 5.208 ± 2.475 mo compared to 5.149 ± 2.366 mo(P = 0.8682) in statically locked exchange nails. The overall union rate of the two procedures, statically and dynamically locked exchange nailing yielded union rates of 84.259% and 82.381% respectively. Therefore, there was no significant difference between the different locking methods of exchange nailing for union rate or time to union at a significance value of P < 0.05. The analysis showed exchange nailing to be the more successful choice in the treatment of femoral non-unions in respect to its higher success rate(491/567 EN, 24/57 dynam, P < 0.0001). However, there was no significant difference between the success rates of the two procedures for delayed union fractures(25/27 EN, 45/55 dynam, P = 0.3299). Nevertheless, dynamization was more efficient in the treatment of delayed unions(at rates comparable to exchange nailing) than in the treatment of non-unions.CONCLUSION In conclusion, after examination of factors, dynamization is recommended treatment of delayed femur fractures, while exchange nailing is the treatment of choice for non-unions.

Effect of Heat Treatment on Delayed Fracture Resistance of High Strength Steel 30CrMnSi2NiNb

The steel specimens of nominal composition 0.3C-1.0Cr-1.0Mn-2.0Si-1.0Ni-0.04 Nb were quenched and tempered or isothermally quenched from various temperatures.It is found that the steel quenched and tempered with a tensile strength of 1 500-1 600 MPa has a KISCC（critical stress intensity factor） value below 15.0 MPa · m1/2.The steel isothermally quenched with a tensile strength of 1 350-1 750 MPa has a KISCC value about 20.0 MPa·m1/2.In addition,with increase of isothermal quenching temperature,the tensile strength decreases greatly and KISCC value does not pronouncedly change.The microstructure of isothermally quenched specimens is composed of bainite and retained austenite.The delayed fracture resistance is dependent on the stability of austenite,which is in turn related to the retained austenite volume fraction and carbon content in austenite.

1300 MPa High Strength Steel for Bolt with Superior Delayed Fracture Resistance

By the increase in Mo content,the addition of microalloying elements V and Nb and by reducing the contents of Mn,P and S based on the composition of steel 42 CrMo,we have developed a 1 300 MPa-grade high strength steel(ADF1)for bolts.The sustained load bending test,sustained load tensile test and stress corrosion cracking test have been carried out to evaluate the delayed fracture resistance of steel ADFl and commercial steel 42 CrMo.The results showed that steel ADF1 has superior delayed fracture resistance to that of 42 CrMo steel.It's concluded that the superior delayed fracture resistance of ADF1 is mainly due to the increase of tempering temperature,fine homogeneously distributed MC carbide and fine prior austenite grain size.

Effect of Boron on Delayed Fracture Resistance of Medium-Carbon High Strength Spring Steel

The delayed fracture behavior of medium carbon high strength spring steel containing different amounts of boron （0. 000 5%, 0. 001 6 %） was studied using sustained load delayed fracture test. The results show that delayed fracture resistance of boron containing steels is higher than that of conventional steel 60Si2MnA at the same strength level and it increases with the increase of boron eontent from 0. 000 5% to 0. 001 6%. The delayed fracture mode is mainly intergranular in the boron containing steels tempered at 350℃, which indicates that the addition of boron does not change the fracture character. However, the increase of boron content enlarges the size of the crack initia tion area. Further study of phase analysis indicates that most boron is in solid solution, and only a very small quantity of boron is in the M3 （C, B） phase.

Delayed fracture of tensile strength 980 MPa grade steels for automotive applications

Three different types of tensile strength （TS） 980 MPa grade advanced high-strength steels used in automotive applications, namely, 980MS （ martensite steel ）, 980DP （ dual phase ） and 980QP （ quenching and partitioning） steels were examined. The delayed fracture resistance of the steels was evaluated using a U-bend test, slow strain rate test（SSRT） and a constant load tensile test. The results indicated that all the steels could pass the 300 h HC1 solution immersion test and none of the U-bend specimens was fractured in the test. However,the steels exhibited different susceptibilities to delayed fracture under SSRT and the constant load tensile tests. 980DP exhibited the highest resistance to delayed fracture among all the samples, while 980MS was found to be the most susceptible to delayed fracture.

Relationship between serum adhesion molecules, trace elements and delayed union of tibial and fibula fractures

Objective:To investigate the relationship between serum adhesion molecules, trace elements and delayed union of tibial and fibula fractures.Methods:A total of 46 patients with delayed union of tibial and fibula fractures in our hospital from May 2014 to June 2016 were selected as the observation group, 46 patients with normal healing of tibial and fibula fractures were selected as the control group, then the serum adhesion molecules and trace elements levels of two groups at forth, eighth and sixteenth week after the surgery were compared.Results:The serum dhesion molecules levels of observation group at forth, eighth and sixteenth week after the surgery were all higher than those of control group, the serum trace elements levels were all lower than those of control group, and the serum adhesion molecules levels of two groups at eighth week after the surgery were all higher than those at other time, the trace elements levels were all lower than those at other time (allP<0.05).Conclusions:The serum adhesion molecules and trace elements of patients with delayed union of tibial and fibula fractures show obviously abnormal state, so those indexes of those patients should be paid to more monitoring and improvement.

Admission delay is associated with worse surgical outcomes for elderly hip fracture patients:A retrospective observational study

BACKGROUND:The influence of surgical delay on mortality and morbidity has been studied extensively among elderly hip fracture patients.However,most studies only focus on the timing of surgery when patients have already been hospitalized,without considering pre-admission waiting time.Therefore,the present study aims to explore the infl uence of admission delay on surgical outcomes.METHODS:In this retrospective study,we recorded admission timing and interval from admission to surgery for included patient.Other covariates were also collected to control confounding.The primary outcome was 1-year mortality.The secondary outcomes were 1-month mortality,3-month mortality,ICU admission and postoperative pneumonia.We mainly used multivariate logistic regression to determine the effect of admission timing on postoperative outcomes.An additional survival analysis was also performed to assess the impact of admission delay on survival status in the fi rst year after operation.RESULTS:The proportion of patients hospitalized on day 0,day 1,day 2 after injury was 25.4%,54.7%and 66.3%,respectively.And 12.6%patients visited hospital one week later after injury.Mean time from admission to surgery was 5.2 days(standard deviation 2.8 days).Hospitalization at one week after injury was a risk factor for 1-year mortality(OR 1.762,95%CI 1.026–3.379,P=0.041).CONCLUSION:Admission delay of more than one week is signifi cantly associated with higher 1-year mortality.As a supplement to the current guidelines which emphasizes early surgery after admission,we also advocate early admission once patients get injured.

Mechanism of Rock Dynamic Delay Fracture Under High Impact

Through the theory and experiment studies on rock dynamic fracture the limit strain is used as the optimum criterion of rock cracking. The main reasons of dynamic delay fracture are the relativity of rock dynamic response with the strain rate and its lower tensile strength. The relation of yielding strain with over-stress impulse and the mechanism of tensile cracking are analysed.

Causes of Surgical Delay and Demographic Characteristics in Patients with Hip Fracture

Background: Several studies analyze how surgical delay affects patients with hip fracture. The aim of this study was to identify the causes of surgical delay and demographic characteristics in patients with hip fracture who had delays longer than 24 hours from admission to hospital. Methods: Quantitative retrospective register study of 484 patients was consecutively included during the period November 1, 2010 and October 31, 2011 in the University Hospital in Lund (Sweden). Results: A frequency of 29.4% had a surgical delay longer than 24 hours. The main reasons for delays to surgery were lack of theatre facilities (54%), medical unstable patient (16%) and anticoagulant treatment (10%). Of all patients, 69% (n = 332) were women and 31% (n = 151) were men. The mean age for women were 83.6 (CI 83-85) vs. 79 (CI 77-81) for men, respectively. The most common type of hip fracture was displaced cervical hip fracture (39%, n = 188) with a majority of fractures in male patients. In total, women suffered hip fractures to a greater extent than men (69% vs. 31%, p = 0.016), but no relationship was found with respect to the fracture type and age (p = 0.358). Conclusion: The main result demonstrated that delays longer than 24 hours were due to lack of theatre facilities. Further researches have to be done in order to investigate whether lack of theatre facilities depends on improper operation planning and/or on lack of medical staff.

Low-intensity extracorporeal shock wave therapy for midshaft clavicular delayed union: A case report and review of literature

BACKGROUND One of the most common complications following surgery for midshaft clavicle fracture is nonunion/delayed union.Extracorporeal shock wave therapy(ESWT)is an alternative to promote new bone formation without surgical complications.To date,no literature has reported low-intensity ESWT(LI-ESWT)in delayed union of midshaft clavicle fracture.CASE SUMMARY We reported a 66-year-old Chinese amateur cyclist with clavicle delayed union treated with 10 sessions of LI-ESWT(radial,0.057 mJ/mm^(2),3 Hz,3000 shocks).No anesthetics were applied,and no side effects occurred.At the 4 mo and 7 mo follow-ups,the patient achieved clinical and radiographical recovery,respectively.CONCLUSION In conclusion,our findings indicated that LI-ESWT could be a good option for treating midshaft clavicular delayed union.

Minimally invasive treatment of forearm double fracture in adult using Acumed forearm intramedullary nail: A case report

BACKGROUND Currently,open reduction internal fixation is the conventional surgical method for treatment of double ulna and radius fracture.However,open reduction is associated with a high risk of complications.This case of forearm double fracture involved a patient treated using an Acumed intramedullary nail.The patient experienced good follow-up outcomes.The Acumed forearm intramedullary nail enables early functional exercise and hastens healing of the fracture.Few studies have reported on the use of this approach for the treatment of fractures.CASE SUMMARY A 23-year-old male patient was admitted to hospital after 5 h of pain,swelling,and limited activity of left forearm caused by a careless fall.Physical examination showed stable basic vital signs,swelling of the left forearm,and severe pain when pressing on the injured part of the forearm.Further,friction was felt at the broken end of the bone;the skin was not punctured.Movement of the left hand was normal,and the left radial artery pulse was normal.Three-dimensional computed tomography examination showed an ulna fracture of the left forearm and comminuted fracture of the radius.The fracture was located in the upper third of the radius,with significant displacement on the fracture side.Clinical diagnosis further confirmed the left radius comminuted fracture and ulna fracture.After analyzing the fracture pattern,age,and other patient characteristics,we chose an Acumed nail for treatment and achieved good follow-up outcomes.CONCLUSION Acumed forearm intramedullary nail for fixation of ulna and radius fracture reduced complication risk and resulted in good follow-up outcomes.

Effect of different surgical methods on traumatic response degree and osteoblast-osteoclast balance in patients with distal tibial fracture

Objective:To study the effect of different surgical methods on trauma response degree and osteoblast-osteoclast balance in patients with distal tibial fracture.Methods:58 cases of patients with distal tibial fracture who received open reduction and internal fixation in Orthopedics Department of our hospital from May 2013 to October 2015 were selected as research subjects and divided into delayed group (n = 29) and routine group (n = 29) according to different timing of surgery. Delayed group received open reduction and internal fixation 7–15 d after trauma and routine group received open reduction and internal fixation within 24 h after trauma. Levels of serum stress response indicators and osteoblast-osteoclast markers were compared between two groups.Results:On the day after operation, serum adrenocorticotropic hormone, cortisol, renin, angiotensin II, epinephrine and norepinephrine levels of delayed group were significantly lower than those of control group (P<0.05);on the 7th day after operation, serum osteocalcin, procollagen type I carboxyl-terminal peptide and bone alkaline phosphatase of delayed group were significantly higher than those of control group (P<0.05) while cross-linked carboxyl-terminal telopeptide of type I collagen and tartrate-resistant acid phosphatase isoform 5b levels were significantly lower than those of control group (P<0.05). Conclusions: Delayed open reduction and internal fixation treatment of distal tibial fracture can reduce the trauma caused by surgical procedures, increase osteoblast viability and inhibit osteoclast viability, which are conducive to fracture healing.

Research advances of nanomaterials for the acceleration of fracture healing

The bone fracture cases have been increasing yearly,accompanied by the increased number of patients experiencing non-union or delayed union after their bone fracture.Although clinical materials facilitate fracture healing(e.g.,metallic and composite materials),they cannot fulfill the requirements due to the slow degradation rate,limited osteogenic activity,inadequate osseointegration ability,and suboptimal mechanical properties.Since early 2000,nanomaterials successfully mimic the nanoscale features of bones and offer unique properties,receiving extensive attention.This paper reviews the achievements of nanomaterials in treating bone fracture(e.g.,the intrinsic properties of nanomaterials,nanomaterials for bone defect filling,and nanoscale drug delivery systems in treating fracture delayed union).Furthermore,we discuss the perspectives on the challenges and future directions of developing nanomaterials to accelerate fracture healing.

Clinical Research on Zishengukang Pill(滋肾骨康丸)Used to Treat Delayed Union of Fracture

Objective:To observe the curative effect of Zishengukang Pill(滋肾骨康丸) on delayed union of fracture.Methods:Sixty-four patients with delayed union of fracture were randomly divided into a control group of 32 cases treated with Western medicine and a treatment group of 32 cases treated with Western medicine and Zishengukang Pill.After 3 courses of treatment with 30 days as a course,the curative effects in the two groups were evaluated and their clinical symptoms,union rate and union time of fracture were compared.Results:The treatment resulted in cure in 25 cases,improvement in 6 cases and ineffectiveness in 1 case with the effective rate at 96.8% in the treatment group,higher than 81.3% in the control group(P<0.05).The union rate of fracture in the treatment group was higher than that in the control group(34.3% vs.12.5%,P<0.05).The union time of fracture in the treatment group was shorter than that in the control group((4.0±1.7) months vs.(5.0±1.4) months,P<0.05).Conclusion:Zishengukang Pill with obvious curative effect in the treatment of delayed union of fracture is worth popularizing.

Delayed Fracture Resistance and Mechanical Properties of 30MnSi High Strength Steel

To investigate the effect of heat treatment on mechanical properties and delayed fracture resistance of high strength steel,30MnSi prestressed concrete （PC） steel bars are quenched and tempered. Tensile results show that,after 950 ℃ quenching and about 430 ℃ tempering,30MnSi PC steel bars have superior mechanical properties and delayed fracture resistance. Microstructural observation shows that 30MnSi steel bar is mainly composed of fine tempered sorbite （troostite） with carbide distributed along the lath martensite boundaries. It can be concluded that thermal refining is an effective way to improve mechanical properties and delayed fracture resistance of 30MnSi PC steel bar.